Abstract

In this article we report on metamaterial-based narrowband thermal terahertz (THz) emitters with a bandwidth of about 1 THz. Single band emitters designed to radiate in the 4 to 8 THz range were found to emit as high as 36 W/m2 when operated at 400 °C. Emission into two well-separated THz bands was also demonstrated by using metamaterial structures featuring more complex unit cells. Imaging of heated emitters using a microbolometer camera fitted with THz optics clearly showed the expected higher emissivity from the metamaterial structure compared to low-emissivity of the surrounding aluminum.

©2012 Optical Society of America

1. Introduction

The continued interest in terahertz (THz) research demands high power sources and sensitive detectors [16]. The energy of photons in THz range of interest (1-10 THz) is relatively low (4-40 meV) requiring complex device architectures for generation [3] and detection [5] at these frequencies. Imaging in this spectral range generally requires an illumination source due to the lack of appreciable background thermal radiation at these frequencies [7, 8]. A number of different techniques have been employed to generate THz radiation [9] with varying power levels. However, the most promising approaches able to generate appreciable power include free electron lasers (FELs) [10] and THz quantum cascade lasers (QCLs) [3, 6, 11], albeit with some drawbacks. For example, FELs generate high power at the expense of requiring a large footprint while the QCLs are compact but only operate at cryogenic temperatures. More recent attempts on THz generation at room temperature include the use of resonant tunneling diode based oscillators [12] and nano-electrodes in a photoconductive photomixer [13], where the generated power levels are still in the microwatt range. An alternative approach to generate THz is to use a heated object with its emissivity tailored to match the specific THz frequency band of interest. The thermal generation of narrowband infrared by controlling emissivity has been demonstrated by using periodic array of holes [14], nano-amorphous carbon [15] and metamaterial structures [16, 17]. In this paper, we report on the realization of narrowband (~1 THz) thermal THz emitters based on metamaterial structures designed to emit at specific frequencies in the 4 to 8 THz spectral region.

2. Design and fabrication

The metamaterial emitters are comprised of a periodic array of Al square unit cells separated from an Al ground plane by a SiO2 layer as schematically illustrated in Fig. 1(a) . Each Al layer is approximately 100 nm thick and the thickness of the SiO2 layer is about 1.6 μm. The dimensions of the Al squares were selected to tune the emissivity (or absorptance) to the desired THz frequency. The design of metamaterial emitters were carried out using 3D finite element modeling COMSOL multiphysics software, where the emissivity characteristics of the structures were simulated for varying Al square sizes. Due to the periodicity of the metamaterial structures, a unit cell as shown in Fig. 1(a) was used in the simulation. The field distribution is calculated for a normally incident plane wave polarized along one of the edges of the Al square. Periodic boundary conditions are applied to the lateral faces of the unit cell. The reflected power as a function of THz frequency (one watt incident power for all frequencies) is calculated by integrating the power flow on the layer boundary, while transmission is assumed to be zero since the ground plane thickness is greater than the skin depth of aluminum in this frequency range (about 80 nm for aluminum at 4 THz). The index of refraction of SiO2 at THz frequencies was taken from [18, 19] as 2.0. The extinction coefficient is frequency dependent in this range and it was taken from [20], varying from 0.025 (4 THz) to 0.08 (8 THz). The conductivity of Al was measured as 1 × 107 S/m. Three metamaterial emitter structures with Al square dimension of 9, 13, 17 μm were fabricated on a silicon substrate using standard microfabrication techniques. The Al ground planes, 100 nm thick, were deposited using e-beam evaporation. The dielectric SiO2 films 1.6 μm thick was deposited using plasma-enhanced chemical vapor deposition (PECVD) followed by e-beam deposition of another layer of Al film, 100 nm thick. Finally, the square arrays were patterned, using plasma sputter etch. Figure 1(b) depicts an optical micrograph of a fabricated metamaterial structure (sample C) showing the periodic array of Al squares. The periodicity of all three samples was kept constant at 21 μm as indicated in Fig. 1(b).

 figure: Fig. 1

Fig. 1 Metamaterial structures comprised of periodically distributed Al squares placed on top of a SiO2 film backed by an Al ground plane, used for single band THz emitters. (a) Schematic diagram of a periodic unit cell used for finite element simulation. (b) Optical micrograph of a fabricated emitter showing the periodic array of Al squares. The inset shows the dimension of Al squares of each sample.

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3. Experimental results

Before measuring the THz emission from the samples, absorption characteristics were determined through reflection spectra using a Fourier transform infrared spectrometer (FTIR Nexus 8700) fitted with a globar source, a Si beamsplitter, a pyroelectric detector and appropriate accessories. The reflectance (R) was measured with the FTIR beam incident at 15° from the normal of the absorber arrays and the absorptance spectrum of each sample was obtained by evaluating (1 – R), since transmittance is zero. Figure 2 shows the absorptance spectra of the three samples in the 3 to 10 THz range revealing clearly separated narrow absorption peaks that move to higher frequencies as the dimension of the Al squares decreases. It was observed that the peak emission frequency depends on the inverse of the size of the aluminum squares (1/a). The explanation of this phenomenon is still under debate and there are different theoretical approaches. The physical mechanism of the absorption effect has been explained by the excitation of localized electromagnetic resonances, especially the magnetic resonance was evidence by the anti-parallel surface currents excited in the two metallic layers [21]. On the other hand, investigation using interference models have shown that the anti-parallel surface currents are reproduced by interference and superposition and there is no magnetic coupling between the metallic layers [22]. In addition, cavity resonance [23], Fabry-Pérot resonance [24] and transmission line [25] models have been proposed. Qualitatively, the interaction of electromagnetic radiation with a metamaterial structure can be described using an equivalent LRC resonator circuit [26] with resonant frequency (=1/LC). Since the capacitance depends on a2, an inverse linear dependence on size (a) is expected for the resonant frequency, which agrees with the experimental observations.

 figure: Fig. 2

Fig. 2 Spectral absorptance of the metamaterial samples A, B and C. Solid lines represent the measured absorptance with peaks at 4.1, 5.4 and 7.8 THz respectively. Dashed lines represent the finite element simulation results.

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It can be seen in Fig. 2 that the absorptance falls from 0.98 (sample A) to 0.85 (sample C), which agrees with that of the COMSOL finite element modeling as indicated by the dashed curves. This is expected due to the use of the same SiO2 layer thickness and structure periodicity for all three samples while in our design, the parameters are selected to maximize the absorption for the sample A [19, 20]. However, by using the appropriate oxide thickness and structure periodicity, it is possible to obtain absorptances close to unity for the samples B and C [27].

The narrowband absorption spectra of the metamaterial structures shown in Fig. 2 suggest that they should also emit radiation at the same THz frequencies when heated based on Kirchhoff's law [28]. The emission spectra of the three samples at 400 °C were measured using the same FTIR spectrometer by directing the emitted radiation to its external port. The samples were placed on top of a hot plate covered by front-coated Al mirrors, which were found to have very low emissivity (~0.02) in the THz spectral range. These mirrors prevent unwanted thermal radiation from the uncovered portions of the hot plate from reaching the FTIR detector. A gold plated 90-degree f/1 off axis parabolic mirror, with focal length of 50 mm was used to collimate the radiation emitted by the metamaterial emitters before directing it to the external port of the FTIR. The emission spectrum of a reference emitter (a silicon wafer coated with black carbon) was used to extract the emissivity of the metamaterial samples as a function of THz frequency. The emissivity spectra, shown in Fig. 3 were obtained by dividing the sample data by the corresponding data obtained using the blackened emitter heated to the same temperature (400 °C).

 figure: Fig. 3

Fig. 3 Measured emissivity of the metamaterial samples A, B and C at 400 °C. Emissivity exhibits peaks at 4.1, 5.4 and 7.8 THz, respectively.

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4. Discussion

It is clear that the emission spectra in Fig. 3 agree well with the measured absorption data in Fig. 2 as expected from Kirchhoff's law. The emission bandwidth at half maximum for each metamaterial structure is approximately 1 THz. The total power emitted into each THz band per unit area (P) can be estimated by integrating Planck's blackbody radiation formula (P(ν)) multiplied by the measured emissivity (ε(ν)) within the emission bandwidth as:

P(ν)=2hc2ε(ν)ν3exp[hνkT]1dν,
where h is Planck’s constant, c is the speed of light in vacuum and k is Boltzmann’s constant. The estimated power per unit area, based on Eq. (1), for samples A, B and C operated at 400 °C is 11, 18 and 36 W/m2 respectively. For comparison, total emission from approximately 300 mm2 area of metamaterial (sample C) is needed to get the average power emitted by a high power QCL operating at 4 THz, which is 5-10 mW [3, 6, 29].

In addition to probing the spectral characteristics of emissivity, dependence of emitted power with temperature was also measured. Figure 4 shows irradiance (the FTIR detector signal) spectra of sample A measured at 140, 280 and 400 °C. The peak emission remained near 4.2 THz, which indicates that thermal expansion of the metamaterial structure in this temperature range is not appreciable. However, the magnitude of the peak emission increased linearly with temperature as shown in the inset of Fig. 4. This behavior is excepted since in 1-10 THz range, Planck's law can be approximated to the Rayleigh-Jeans [30] limit ( < kT) which is given by:

P(ν)2kTν2c2.
The temperature dependence in Eq. (2) confirms that the emitted power is proportional to the temperature as observed experimentally.

 figure: Fig. 4

Fig. 4 Spectral irradiance of Sample A, measured at 140, 280 and 400 °C. The inset shows that the measured peak emission (solid squares) depends linearly with temperature (solid line).

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The emissivity spectrum can be extended to multiple well-separated bands by designing metamaterial THz emitters with the appropriate geometry. A dual-band THz emitter was fabricated (sample D) and characterized using the same procedure employed for the other samples. Since all the samples were fabricated on the same wafer, the dielectric layer (SiO2) thickness remained the same at 1.6 μm. In this case, the top layer of the dual-band metamaterial consists of two different size squares (10 and 18 μm) distributed in a tile-like arrangement as shown in the inset of Fig. 5 . The measured emissivity of the sample at 400 °C multiplied by the Planck's blackbody radiation formula (excitance) at 400 °C is shown in Fig. 5. The blackbody spectrum is also plotted (dashed line) as evidence that high emissivity was achieved for both bands. The smaller squares are responsible for the higher frequency resonance at 6.8 THz and the larger squares are responsible for the lower frequency resonance at 4.0 THz.

 figure: Fig. 5

Fig. 5 Radiant exitance of the dual band metamaterial (sample D) at 400 °C. The dashed line represents the blackbody curve at the same temperature. The inset shows the metamaterial pattern with two different size squares (10 and 18 μm) distributed in a tile like arrangement.

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The ability to choose the appropriate dimensions and combinations of squares in addition to the dielectric material and thickness to produce the desired response makes metamaterials an attractive option to engineer a specific THz emission profile. The enhanced THz emission from the metamaterial structures was also observed using a microbolometer infrared camera fitted with a Tsurupica lens, which ensured that only THz radiation reached the camera. Note that the camera is not optimized for THz imaging [8, 30]. Figure 6(a) shows the THz image of metamaterial structures on samples B and C, heated to 400 °C while Fig. 6(b) shows the image in the visible range taken by a standard digital camera. In the THz image it is easy to identify the metamaterial regions (brighter), the aluminum lines that separates the metamaterial structures (darker) and also the exposed SiO2 ring, which was found to have substantially higher emissivity than that of Al in the THz spectral range the camera lens transmits (see the inset in Fig. 6(c)).

 figure: Fig. 6

Fig. 6 THz images of metamaterial samples B and C heated to 400 °C. (a) Picture taken by a microbolometer camera fitted with THZ optics. (b) Corresponding picture taken by a standard visible digital camera. (c) Spectral transmittance of Tsurupica lens (dashed line) along with irradiance spectra of the sample C (blue solid line) and a uniform Al film (red solid line). The inset in (c) shows the Tsurupica transmittance extended to IR range.

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Figure 6(c) shows the transmittance of Tsurupica lens along with the irradiance spectra of sample B and a uniform Al film. The data in Fig. 6(c) shows that emitted THz power from Al is much smaller than that of the metamaterial. The low emissivity of Al relative to the metamaterial structures is responsible for dark lines in the THz image. The inset in Fig. 6(c) shows the transmission spectrum of Tsurupica, which has relatively good transmission in THz range while blocking most of the 7-13 μm infrared range, for which the camera has high sensitivity [31]. This assures that the image in Fig. 6(a) is primarily due to emitted THz radiation.

5. Conclusion

In summary, we have demonstrated metamaterial-based selective emitters operating with near unity peak emissivities with peaks in the 4 to 8 THz interval. The absorption characteristics agree well with the measured emissivities showing that Kirchhoff’s law applies to metamaterials in the THz range. Furthermore, emitted THz power from the samples has a linear dependence on temperature since emission in this range can be approximated to the Rayleigh-Jeans limit. Multiband THz emission capabilities were also demonstrated using more complex unit cells in the metamaterial. Design accuracy, fabrication simplicity and high power make the metamaterial emitters very attractive for applications that seek narrow band THz sources.

Acknowledgments

This work is supported in part by a grant from the ONR. The authors would like to thank Brett Borden and James Luscombe for helpful discussions and Emmanuel Dupont, Nick Lavrik and Sam Barone for technical assistance. A portion of this research was conducted at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.

References and links

1. D. L. Woolard, E. R. Brown, M. Pepper, and M. Kemp, “Terahertz frequency sensing and imaging: A time of reckoning future applications?” in Proceedings of IEEE Vol. 93(10) Special Issue on: Blue Sky Electronic Technology (Institute of Electrical and Electronics Engineers, New York, 2005), pp. 1722–1743.

2. J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005). [CrossRef]  

3. B. S. Williams, “Terahertz quantum-cascade lasers,” Nat. Photonics 1(9), 517–525 (2007). [CrossRef]  

4. I. Hosako, N. Sekine, M. Patrashin, S. Saito, K. Fukunaga, Y. Kasai, P. Baron, T. Seta, J. Mendrok, S. Ochiai, and H. Yasuda, “At the dawn of a new era in terahertz technology” in Proceedings of IEEE Vol. 95(8) Special issue on: T-Ray Imaging Sensing, & Retection (Institute of Electrical and Electronics Engineers, New York, 2007), 1611–1623.

5. A. Rogalski and F. Sizov, “Terahertz detectors and focal plane arrays,” Opto-Electron. Rev. 19(3), 346–404 (2011). [CrossRef]  

6. S. Kumar, “Recent progress in terahertz quantum cascade lasers,” IEEE J. Sel. Top. Quantum Electron. 17(1), 38–47 (2011). [CrossRef]  

7. A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006). [CrossRef]  

8. B. N. Behnken, G. Karunasiri, D. R. Chamberlin, P. R. Robrish, and J. Faist, “Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera,” Opt. Lett. 33(5), 440–442 (2008). [CrossRef]   [PubMed]  

9. M. S. Shur and V. Ryzhii, “ New concepts for submillimeter-wave detection and generation,” in Proceedings of 11th GaAs applications symposium, (Munich, 2003), 301–304.

10. G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002). [CrossRef]   [PubMed]  

11. R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002). [CrossRef]   [PubMed]  

12. M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011). [CrossRef]  

13. H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012). [CrossRef]  

14. Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010). [CrossRef]  

15. S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009). [CrossRef]  

16. X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011). [CrossRef]   [PubMed]  

17. J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011). [CrossRef]  

18. M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001). [CrossRef]  

19. D. Y. Smith, E. Shiles, and M. Inokuti, “Silicon Dioxide (SiO2),” in Handbook of Optical Constants of Solids Part 2, E. D. Palik, ed. (Academic, 1998).

20. R. Kitamura, L. Pilon, and M. Jonasz, “Optical constants of silica glass from extreme ultraviolet to far infrared at near room temperature,” Appl. Opt. 46(33), 8118–8133 (2007). [CrossRef]   [PubMed]  

21. H. Tao, N. I. Landy, C. M. Bingham, X. Zhang, R. D. Averitt, and W. J. Padilla, “A metamaterial absorber for the terahertz regime: Design, fabrication and characterization,” Opt. Express 16(10), 7181–7188 (2008). [CrossRef]   [PubMed]  

22. H.-T. Chen, “Interference theory of metamaterial perfect absorbers,” Opt. Express 20(7), 7165–7172 (2012). [CrossRef]   [PubMed]  

23. D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010). [CrossRef]  

24. H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010). [CrossRef]   [PubMed]  

25. Q. Y. Wen, Y. S. Xie, H. W. Zhang, Q. H. Yang, Y. X. Li, and Y. L. Liu, “Transmission line model and fields analysis of metamaterial absorber in the terahertz band,” Opt. Express 17(22), 20256–20265 (2009). [CrossRef]   [PubMed]  

26. T. Maier and H. Brückl, “Wavelength-tunable microbolometers with metamaterial absorbers,” Opt. Lett. 34(19), 3012–3014 (2009). [CrossRef]   [PubMed]  

27. F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012). [CrossRef]  

28. G. Kirchhoff, “On the relation between the radiating and the absorbing powers of different bodies for light and heat,” Philos. Mag. 20, 1–21 (1860).

29. S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008). [CrossRef]  

30. J. M. Palmer and B. G. Grant, “The Art of Radiometry,” ed. (SPIE Press, 2010).

31. R. A. Wood, “Monolithic silicon microbolometer arrays,” in Semiconductors and Semimetals47: Uncooled Infrared Imaging Arrays and Systems, P. W. Kruse and D.D. Skatrud, eds. (Academic Press, 1997).

References

  • View by:

  1. D. L. Woolard, E. R. Brown, M. Pepper, and M. Kemp, “Terahertz frequency sensing and imaging: A time of reckoning future applications?” in Proceedings of IEEE Vol. 93(10) Special Issue on: Blue Sky Electronic Technology (Institute of Electrical and Electronics Engineers, New York, 2005), pp. 1722–1743.
  2. J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
    [Crossref]
  3. B. S. Williams, “Terahertz quantum-cascade lasers,” Nat. Photonics 1(9), 517–525 (2007).
    [Crossref]
  4. I. Hosako, N. Sekine, M. Patrashin, S. Saito, K. Fukunaga, Y. Kasai, P. Baron, T. Seta, J. Mendrok, S. Ochiai, and H. Yasuda, “At the dawn of a new era in terahertz technology” in Proceedings of IEEE Vol. 95(8) Special issue on: T-Ray Imaging Sensing, & Retection (Institute of Electrical and Electronics Engineers, New York, 2007), 1611–1623.
  5. A. Rogalski and F. Sizov, “Terahertz detectors and focal plane arrays,” Opto-Electron. Rev. 19(3), 346–404 (2011).
    [Crossref]
  6. S. Kumar, “Recent progress in terahertz quantum cascade lasers,” IEEE J. Sel. Top. Quantum Electron. 17(1), 38–47 (2011).
    [Crossref]
  7. A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
    [Crossref]
  8. B. N. Behnken, G. Karunasiri, D. R. Chamberlin, P. R. Robrish, and J. Faist, “Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera,” Opt. Lett. 33(5), 440–442 (2008).
    [Crossref] [PubMed]
  9. M. S. Shur and V. Ryzhii, “ New concepts for submillimeter-wave detection and generation,” in Proceedings of 11th GaAs applications symposium, (Munich, 2003), 301–304.
  10. G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
    [Crossref] [PubMed]
  11. R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
    [Crossref] [PubMed]
  12. M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
    [Crossref]
  13. H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
    [Crossref]
  14. Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
    [Crossref]
  15. S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
    [Crossref]
  16. X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
    [Crossref] [PubMed]
  17. J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011).
    [Crossref]
  18. M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
    [Crossref]
  19. D. Y. Smith, E. Shiles, and M. Inokuti, “Silicon Dioxide (SiO2),” in Handbook of Optical Constants of Solids Part 2, E. D. Palik, ed. (Academic, 1998).
  20. R. Kitamura, L. Pilon, and M. Jonasz, “Optical constants of silica glass from extreme ultraviolet to far infrared at near room temperature,” Appl. Opt. 46(33), 8118–8133 (2007).
    [Crossref] [PubMed]
  21. H. Tao, N. I. Landy, C. M. Bingham, X. Zhang, R. D. Averitt, and W. J. Padilla, “A metamaterial absorber for the terahertz regime: Design, fabrication and characterization,” Opt. Express 16(10), 7181–7188 (2008).
    [Crossref] [PubMed]
  22. H.-T. Chen, “Interference theory of metamaterial perfect absorbers,” Opt. Express 20(7), 7165–7172 (2012).
    [Crossref] [PubMed]
  23. D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
    [Crossref]
  24. H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
    [Crossref] [PubMed]
  25. Q. Y. Wen, Y. S. Xie, H. W. Zhang, Q. H. Yang, Y. X. Li, and Y. L. Liu, “Transmission line model and fields analysis of metamaterial absorber in the terahertz band,” Opt. Express 17(22), 20256–20265 (2009).
    [Crossref] [PubMed]
  26. T. Maier and H. Brückl, “Wavelength-tunable microbolometers with metamaterial absorbers,” Opt. Lett. 34(19), 3012–3014 (2009).
    [Crossref] [PubMed]
  27. F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
    [Crossref]
  28. G. Kirchhoff, “On the relation between the radiating and the absorbing powers of different bodies for light and heat,” Philos. Mag. 20, 1–21 (1860).
  29. S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
    [Crossref]
  30. J. M. Palmer and B. G. Grant, “The Art of Radiometry,” ed. (SPIE Press, 2010).
  31. R. A. Wood, “Monolithic silicon microbolometer arrays,” in Semiconductors and Semimetals47: Uncooled Infrared Imaging Arrays and Systems, P. W. Kruse and D.D. Skatrud, eds. (Academic Press, 1997).

2012 (3)

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

H.-T. Chen, “Interference theory of metamaterial perfect absorbers,” Opt. Express 20(7), 7165–7172 (2012).
[Crossref] [PubMed]

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

2011 (5)

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011).
[Crossref]

M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
[Crossref]

A. Rogalski and F. Sizov, “Terahertz detectors and focal plane arrays,” Opto-Electron. Rev. 19(3), 346–404 (2011).
[Crossref]

S. Kumar, “Recent progress in terahertz quantum cascade lasers,” IEEE J. Sel. Top. Quantum Electron. 17(1), 38–47 (2011).
[Crossref]

2010 (3)

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
[Crossref]

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

2009 (3)

2008 (3)

2007 (2)

2006 (1)

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

2005 (1)

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

2002 (2)

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

2001 (1)

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[Crossref]

1860 (1)

G. Kirchhoff, “On the relation between the radiating and the absorbing powers of different bodies for light and heat,” Philos. Mag. 20, 1–21 (1860).

Alves, F.

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

Araci, I. E.

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

Averitt, R. D.

Azad, A. K.

D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
[Crossref]

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

Ban, D.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Barat, R.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Beere, H. E.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Behnken, B. N.

Beltram, F.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Bingham, C. M.

Boucherif, A.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Brückl, H.

Carr, G. L.

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

Chamberlin, D. R.

Chang, P.-E.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Chang, Y.-T.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Chen, F.

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

Chen, H.-H.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Chen, H.-T.

H.-T. Chen, “Interference theory of metamaterial perfect absorbers,” Opt. Express 20(7), 7165–7172 (2012).
[Crossref] [PubMed]

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

Chen, Z. N.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Chua, S. J.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Chum, C. C.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Cojocari, O.

M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
[Crossref]

Danner, A. J.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Davies, A. G.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Dupont, E.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Faist, J.

Fathololoumi, S.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Federici, J. F.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Feiginov, M.

M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
[Crossref]

Gary, D.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Grbovic, D.

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

Gunde, M. K.

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[Crossref]

Huang, F.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Huang, H.-F.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Iotti, R. C.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Jiang, Y.-W.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Jokerst, N. M.

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

Jonasz, M.

Jordan, K.

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

Karunasiri, G.

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

B. N. Behnken, G. Karunasiri, D. R. Chamberlin, P. R. Robrish, and J. Faist, “Real-time imaging using a 2.8 THz quantum cascade laser and uncooled infrared microbolometer camera,” Opt. Lett. 33(5), 440–442 (2008).
[Crossref] [PubMed]

Kearney, B.

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

Kirchhoff, G.

G. Kirchhoff, “On the relation between the radiating and the absorbing powers of different bodies for light and heat,” Philos. Mag. 20, 1–21 (1860).

Kitamura, R.

Köhler, R.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Kropachev, A.

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

Kumar, S.

S. Kumar, “Recent progress in terahertz quantum cascade lasers,” IEEE J. Sel. Top. Quantum Electron. 17(1), 38–47 (2011).
[Crossref]

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

Laframboise, S. R.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Landy, N. I.

Lavrik, N. V.

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

Lee, A. W. M.

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

Lee, S. C.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Li, Y. X.

Linfield, E. H.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Liu, H. C.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Liu, X.

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

Liu, Y. L.

Luo, H.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

Macek, M.

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[Crossref]

Maier, S. A.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Maier, T.

Martin, M. C.

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

Mason, J. J. A.

J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011).
[Crossref]

McKinney, W. R.

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

Meissner, P.

M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
[Crossref]

Neil, G. R.

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

Norwood, R. A.

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

O’Hara, J. F.

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
[Crossref]

Oliveira, F.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Padilla, W. J.

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

H. Tao, N. I. Landy, C. M. Bingham, X. Zhang, R. D. Averitt, and W. J. Padilla, “A metamaterial absorber for the terahertz regime: Design, fabrication and characterization,” Opt. Express 16(10), 7181–7188 (2008).
[Crossref] [PubMed]

Peyghambarian, N.

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

Pilon, L.

Qing Hu,

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

Reno, J. L.

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

Ritchie, D. A.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Robrish, P. R.

Rogalski, A.

A. Rogalski and F. Sizov, “Terahertz detectors and focal plane arrays,” Opto-Electron. Rev. 19(3), 346–404 (2011).
[Crossref]

Rossi, F.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Schulkin, B.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Shchegolkov, D. Y.

D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
[Crossref]

Si, G. Y.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Simakov, E. I.

D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
[Crossref]

Sizov, F.

A. Rogalski and F. Sizov, “Terahertz detectors and focal plane arrays,” Opto-Electron. Rev. 19(3), 346–404 (2011).
[Crossref]

Skotheim, T.

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

Smith, S.

J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011).
[Crossref]

Starr, A. F.

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

Starr, T.

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

Sun, M.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Sydlo, C.

M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
[Crossref]

Tanoto, H.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Tao, H.

Tay, S.

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

Taylor, A. J.

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

Teng, J. H.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Tredicucci, A.

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Tyler, T.

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

Tzuang, D.-C.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Wang, B.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Wasserman, D.

J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011).
[Crossref]

Wen, Q. Y.

Wil, B. S.

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

Williams, B. S.

B. S. Williams, “Terahertz quantum-cascade lasers,” Nat. Photonics 1(9), 517–525 (2007).
[Crossref]

Williams, G. P.

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

Wu, Q. Y.

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

Wu, Y. T.

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Xie, Y. S.

Yang, Q. H.

Zhang, H. W.

Zhang, X.

Zhou, J.

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

Zimdars, D.

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

Appl. Opt. (1)

Appl. Phys. Lett. (4)

J. J. A. Mason, S. Smith, and D. Wasserman, “Strong absorption and selective thermal emission from a midinfrared metamaterial,” Appl. Phys. Lett. 98(24), 241105 (2011).
[Crossref]

F. Alves, B. Kearney, D. Grbovic, N. V. Lavrik, and G. Karunasiri, “Strong terahertz absorption using SiO2/Al based metamaterial structures,” Appl. Phys. Lett. 100(11), 111104 (2012).
[Crossref]

M. Feiginov, C. Sydlo, O. Cojocari, and P. Meissner, “Resonant-tunneling-diode oscillators operating at frequencies above 1.1 THz,” Appl. Phys. Lett. 99(23), 233506 (2011).
[Crossref]

S. Tay, A. Kropachev, I. E. Araci, T. Skotheim, R. A. Norwood, and N. Peyghambarian, “Plasmonic thermal IR emitters based on nanoamorphous carbon,” Appl. Phys. Lett. 94(7), 071113 (2009).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (1)

S. Kumar, “Recent progress in terahertz quantum cascade lasers,” IEEE J. Sel. Top. Quantum Electron. 17(1), 38–47 (2011).
[Crossref]

IEEE Jour. Quan. Elec. (1)

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE Jour. Quan. Elec. 44(12), 1139–1144 (2008).
[Crossref]

IEEE Photon. Technol. Lett. (2)

A. W. M. Lee, B. S. Wil, S. Kumar, Qing Hu, and J. L. Reno, “Real-time imaging using a 4.3-THz quantum cascade laser and a 320 /spl times/ 240 microbolometer focal-plane array,” IEEE Photon. Technol. Lett. 18(13), 1415–1417 (2006).
[Crossref]

Y. T. Wu, Y.-T. Chang, H.-H. Chen, H.-F. Huang, D.-C. Tzuang, Y.-W. Jiang, P.-E. Chang, and S. C. Lee, “Narrow bandwidth midinfrared waveguide thermal emitters,” IEEE Photon. Technol. Lett. 22(15), 1159–1161 (2010).
[Crossref]

Nat. Photonics (2)

H. Tanoto, J. H. Teng, Q. Y. Wu, M. Sun, Z. N. Chen, S. A. Maier, B. Wang, C. C. Chum, G. Y. Si, A. J. Danner, and S. J. Chua, “Greatly enhanced continuous-wave terahertz emission by nano-electrodes in a photoconductive photomixer,” Nat. Photonics 6(2), 121–126 (2012).
[Crossref]

B. S. Williams, “Terahertz quantum-cascade lasers,” Nat. Photonics 1(9), 517–525 (2007).
[Crossref]

Nature (2)

G. L. Carr, M. C. Martin, W. R. McKinney, K. Jordan, G. R. Neil, and G. P. Williams, “High-power terahertz radiation from relativistic electrons,” Nature 420(6912), 153–156 (2002).
[Crossref] [PubMed]

R. Köhler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. A. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417(6885), 156–159 (2002).
[Crossref] [PubMed]

Opt. Express (3)

Opt. Lett. (2)

Opto-Electron. Rev. (1)

A. Rogalski and F. Sizov, “Terahertz detectors and focal plane arrays,” Opto-Electron. Rev. 19(3), 346–404 (2011).
[Crossref]

Philos. Mag. (1)

G. Kirchhoff, “On the relation between the radiating and the absorbing powers of different bodies for light and heat,” Philos. Mag. 20, 1–21 (1860).

Phys. Rev. B (1)

D. Y. Shchegolkov, A. K. Azad, J. F. O’Hara, and E. I. Simakov, “Perfect subwavelength fishnet like metamaterial-based film terahertz absorbers,” Phys. Rev. B 82(20), 205117 (2010).
[Crossref]

Phys. Rev. Lett. (2)

H.-T. Chen, J. Zhou, J. F. O’Hara, F. Chen, A. K. Azad, and A. J. Taylor, “Antireflection coating using metamaterials and identification of its mechanism,” Phys. Rev. Lett. 105(7), 073901 (2010).
[Crossref] [PubMed]

X. Liu, T. Tyler, T. Starr, A. F. Starr, N. M. Jokerst, and W. J. Padilla, “Taming the blackbody with infrared metamaterials as selective thermal emitters,” Phys. Rev. Lett. 107(4), 045901 (2011).
[Crossref] [PubMed]

Phys. Status Solidi A (1)

M. K. Gunde and M. Macek, “Infrared optical constants and dielectric response functions of silicon nitride and oxynitride films,” Phys. Status Solidi A 183, 439–449 (2001).
[Crossref]

Semicond. Sci. Technol. (1)

J. F. Federici, B. Schulkin, F. Huang, D. Gary, R. Barat, F. Oliveira, and D. Zimdars, “THz imaging and sensing for security applications—explosives, weapons and drugs,” Semicond. Sci. Technol. 20(7), S266–S280 (2005).
[Crossref]

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D. L. Woolard, E. R. Brown, M. Pepper, and M. Kemp, “Terahertz frequency sensing and imaging: A time of reckoning future applications?” in Proceedings of IEEE Vol. 93(10) Special Issue on: Blue Sky Electronic Technology (Institute of Electrical and Electronics Engineers, New York, 2005), pp. 1722–1743.

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M. S. Shur and V. Ryzhii, “ New concepts for submillimeter-wave detection and generation,” in Proceedings of 11th GaAs applications symposium, (Munich, 2003), 301–304.

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Figures (6)

Fig. 1
Fig. 1 Metamaterial structures comprised of periodically distributed Al squares placed on top of a SiO2 film backed by an Al ground plane, used for single band THz emitters. (a) Schematic diagram of a periodic unit cell used for finite element simulation. (b) Optical micrograph of a fabricated emitter showing the periodic array of Al squares. The inset shows the dimension of Al squares of each sample.
Fig. 2
Fig. 2 Spectral absorptance of the metamaterial samples A, B and C. Solid lines represent the measured absorptance with peaks at 4.1, 5.4 and 7.8 THz respectively. Dashed lines represent the finite element simulation results.
Fig. 3
Fig. 3 Measured emissivity of the metamaterial samples A, B and C at 400 °C. Emissivity exhibits peaks at 4.1, 5.4 and 7.8 THz, respectively.
Fig. 4
Fig. 4 Spectral irradiance of Sample A, measured at 140, 280 and 400 °C. The inset shows that the measured peak emission (solid squares) depends linearly with temperature (solid line).
Fig. 5
Fig. 5 Radiant exitance of the dual band metamaterial (sample D) at 400 °C. The dashed line represents the blackbody curve at the same temperature. The inset shows the metamaterial pattern with two different size squares (10 and 18 μm) distributed in a tile like arrangement.
Fig. 6
Fig. 6 THz images of metamaterial samples B and C heated to 400 °C. (a) Picture taken by a microbolometer camera fitted with THZ optics. (b) Corresponding picture taken by a standard visible digital camera. (c) Spectral transmittance of Tsurupica lens (dashed line) along with irradiance spectra of the sample C (blue solid line) and a uniform Al film (red solid line). The inset in (c) shows the Tsurupica transmittance extended to IR range.

Equations (2)

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P( ν )= 2h c 2 ε( ν ) ν 3 exp[ hν kT ]1 dν,
P( ν ) 2kT ν 2 c 2 .

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