Abstract

We propose a fiber-based, terahertz-comb-referenced spectrum analyzer which has the advantages of being a portable, alignment-free, robust, and flexible apparatus suitable for practical use. To this end, we constructed a 1550-nm mode-locked Er-doped fiber laser whose mode-locked frequency was stabilized precisely by referring to a rubidium frequency standard, and used it to generate a highly stable terahertz (THz) frequency comb in a photoconductive antenna or an electro-optic crystal. By standardizing the THz comb, we determined the frequency accuracy of an active-frequency-multiplier-chain (AFMC) source to be 2.4 × 10−11. Furthermore, the potential of the THz spectrum analyzer was effectively demonstrated by real-time monitoring of the spectral behavior of the AFMC source and a photomixing source of two free-running CW lasers at adjacent wavelengths.

© 2009 OSA

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References

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  1. S. Yokoyama, R. Nakamura, M. Nose, T. Araki, and T. Yasui, “Terahertz spectrum analyzer based on a terahertz frequency comb,” Opt. Express 16(17), 13052–13061 (2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13052 .
    [CrossRef] [PubMed]
  2. T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
    [CrossRef]
  3. P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
    [CrossRef]
  4. B. Sartorius, H. Roehle, H. Künzel, J. Böttcher, M. Schlak, D. Stanze, H. Venghaus, and M. Schell, “All-fiber terahertz time-domain spectrometer operating at 1.5 microm telecom wavelengths,” Opt. Express 16(13), 9565–9570 (2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-13-9565 .
    [CrossRef] [PubMed]
  5. J. Ward, E. Schlecht, G. Chattopadhyay, A. Maestrini, J. Gill, F. Maiwald, H. Javadi, and I. Mehdi, “Capability of THz sources based on Schottky diode frequency multiplier chains,” in Proceedings of IEEE MTT-S International Microwave Symposium (Institute of Electrical and Electronics Engineers, Fort Worth, 2004), pp. 1587–1590.
  6. T. Nagatsuma, H. Ito, and T. Ishibashi, “High-power RF photodiodes and their applications,” Laser, Photon. Rev. 3(1-2), 123–137 (2009).
  7. H. Inaba, Y. Daimon, F.-L. Hong, A. Onae, K. Minoshima, T. R. Schibli, H. Matsumoto, M. Hirano, T. Okuno, M. Onishi, and M. Nakazawa, “Long-term measurement of optical frequencies using a simple, robust and low-noise fiber based frequency comb,” Opt. Express 14(12), 5223–5231 (2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-12-5223 .
    [CrossRef] [PubMed]
  8. M. Tani, K.-S. Lee, and X.-C. Zhang, “Detection of terahertz radiation with low-temperature-grown GaAs-based photoconductive antenna using 1.55 µm probe,” Appl. Phys. Lett. 77(9), 1396–1398 (2000).
    [CrossRef]
  9. T. Löffler and T. May, “C. am Weg, A. Alcin, B. Hils and H. G. Roskos. “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).
  10. T. Yasui, H. Takahashi, Y. Iwamoto, H. Inaba, and K. Minoshima, “Widely tunable, phase-locked CW-THz radiation by photomixing of two CW lasers locked to two independent fiber combs,” in Conference on Lasers and Electro-Optics (CLEO)2009, Technical Digest (CD) (Optical Society of America, 2009), paper CWB7. http://www.opticsinfobase.org/abstract.cfm?URI=CLEO-2009-CWB7 .
  11. M. Ashida, R. Akai, H. Shimosato, I. Katayama, T. Itoh, K. Miyamoto, and H. Ito, “Ultrabroadband THz field detection beyond 170THz with a photoconductive antenna,” in Conference on Lasers and Electro-Optics (CLEO)2008, Technical Digest (CD) (Optical Society of America, 2008), paper CTuX6. http://www.opticsinfobase.org/abstract.cfm?URI=CLEO-2008-CTuX6 .

2009

T. Nagatsuma, H. Ito, and T. Ishibashi, “High-power RF photodiodes and their applications,” Laser, Photon. Rev. 3(1-2), 123–137 (2009).

2008

2007

T. Löffler and T. May, “C. am Weg, A. Alcin, B. Hils and H. G. Roskos. “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).

P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
[CrossRef]

2006

2000

M. Tani, K.-S. Lee, and X.-C. Zhang, “Detection of terahertz radiation with low-temperature-grown GaAs-based photoconductive antenna using 1.55 µm probe,” Appl. Phys. Lett. 77(9), 1396–1398 (2000).
[CrossRef]

Araki, T.

S. Yokoyama, R. Nakamura, M. Nose, T. Araki, and T. Yasui, “Terahertz spectrum analyzer based on a terahertz frequency comb,” Opt. Express 16(17), 13052–13061 (2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13052 .
[CrossRef] [PubMed]

T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
[CrossRef]

Böttcher, J.

Daimon, Y.

Gaal, P.

P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
[CrossRef]

Hirano, M.

Hong, F.-L.

Inaba, H.

Ishibashi, T.

T. Nagatsuma, H. Ito, and T. Ishibashi, “High-power RF photodiodes and their applications,” Laser, Photon. Rev. 3(1-2), 123–137 (2009).

Ito, H.

T. Nagatsuma, H. Ito, and T. Ishibashi, “High-power RF photodiodes and their applications,” Laser, Photon. Rev. 3(1-2), 123–137 (2009).

Kabetani, Y.

T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
[CrossRef]

Künzel, H.

Lee, K.-S.

M. Tani, K.-S. Lee, and X.-C. Zhang, “Detection of terahertz radiation with low-temperature-grown GaAs-based photoconductive antenna using 1.55 µm probe,” Appl. Phys. Lett. 77(9), 1396–1398 (2000).
[CrossRef]

Löffler, T.

T. Löffler and T. May, “C. am Weg, A. Alcin, B. Hils and H. G. Roskos. “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).

Matsumoto, H.

May, T.

T. Löffler and T. May, “C. am Weg, A. Alcin, B. Hils and H. G. Roskos. “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).

Minoshima, K.

Nagatsuma, T.

T. Nagatsuma, H. Ito, and T. Ishibashi, “High-power RF photodiodes and their applications,” Laser, Photon. Rev. 3(1-2), 123–137 (2009).

Nakamura, R.

Nakazawa, M.

Nose, M.

Okuno, T.

Onae, A.

Onishi, M.

Raschke, M. B.

P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
[CrossRef]

Reimann, K.

P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
[CrossRef]

Roehle, H.

Saneyoshi, E.

T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
[CrossRef]

Sartorius, B.

Schell, M.

Schibli, T. R.

Schlak, M.

Stanze, D.

Tani, M.

M. Tani, K.-S. Lee, and X.-C. Zhang, “Detection of terahertz radiation with low-temperature-grown GaAs-based photoconductive antenna using 1.55 µm probe,” Appl. Phys. Lett. 77(9), 1396–1398 (2000).
[CrossRef]

Venghaus, H.

Woerner, M.

P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
[CrossRef]

Yasui, T.

S. Yokoyama, R. Nakamura, M. Nose, T. Araki, and T. Yasui, “Terahertz spectrum analyzer based on a terahertz frequency comb,” Opt. Express 16(17), 13052–13061 (2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13052 .
[CrossRef] [PubMed]

T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
[CrossRef]

Yokoyama, S.

S. Yokoyama, R. Nakamura, M. Nose, T. Araki, and T. Yasui, “Terahertz spectrum analyzer based on a terahertz frequency comb,” Opt. Express 16(17), 13052–13061 (2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13052 .
[CrossRef] [PubMed]

T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
[CrossRef]

Zhang, X.-C.

M. Tani, K.-S. Lee, and X.-C. Zhang, “Detection of terahertz radiation with low-temperature-grown GaAs-based photoconductive antenna using 1.55 µm probe,” Appl. Phys. Lett. 77(9), 1396–1398 (2000).
[CrossRef]

Appl. Phys. Lett.

M. Tani, K.-S. Lee, and X.-C. Zhang, “Detection of terahertz radiation with low-temperature-grown GaAs-based photoconductive antenna using 1.55 µm probe,” Appl. Phys. Lett. 77(9), 1396–1398 (2000).
[CrossRef]

T. Löffler and T. May, “C. am Weg, A. Alcin, B. Hils and H. G. Roskos. “Continuous-wave terahertz imaging with a hybrid system,” Appl. Phys. Lett. 90, 091111 (2007).

T. Yasui, Y. Kabetani, E. Saneyoshi, S. Yokoyama, and T. Araki, “Terahertz frequency comb by multi-frequency-heterodyning photoconductive detection for high-accuracy, high-resolution terahertz spectroscopy,” Appl. Phys. Lett. 88(24), 241104 (2006).
[CrossRef]

Laser,

T. Nagatsuma, H. Ito, and T. Ishibashi, “High-power RF photodiodes and their applications,” Laser, Photon. Rev. 3(1-2), 123–137 (2009).

Nat. Photonics

P. Gaal, M. B. Raschke, K. Reimann, and M. Woerner, “Measuring optical frequencies in the 0–40 THz range with non-synchronized electro–optic sampling,” Nat. Photonics 1(10), 577–580 (2007).
[CrossRef]

Opt. Express

Other

J. Ward, E. Schlecht, G. Chattopadhyay, A. Maestrini, J. Gill, F. Maiwald, H. Javadi, and I. Mehdi, “Capability of THz sources based on Schottky diode frequency multiplier chains,” in Proceedings of IEEE MTT-S International Microwave Symposium (Institute of Electrical and Electronics Engineers, Fort Worth, 2004), pp. 1587–1590.

T. Yasui, H. Takahashi, Y. Iwamoto, H. Inaba, and K. Minoshima, “Widely tunable, phase-locked CW-THz radiation by photomixing of two CW lasers locked to two independent fiber combs,” in Conference on Lasers and Electro-Optics (CLEO)2009, Technical Digest (CD) (Optical Society of America, 2009), paper CWB7. http://www.opticsinfobase.org/abstract.cfm?URI=CLEO-2009-CWB7 .

M. Ashida, R. Akai, H. Shimosato, I. Katayama, T. Itoh, K. Miyamoto, and H. Ito, “Ultrabroadband THz field detection beyond 170THz with a photoconductive antenna,” in Conference on Lasers and Electro-Optics (CLEO)2008, Technical Digest (CD) (Optical Society of America, 2008), paper CTuX6. http://www.opticsinfobase.org/abstract.cfm?URI=CLEO-2008-CTuX6 .

Supplementary Material (3)

» Media 1: MOV (3820 KB)     
» Media 2: MOV (3296 KB)     
» Media 3: MOV (3898 KB)     

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Figures (9)

Fig. 1
Fig. 1

Experimental setup.

Fig. 2
Fig. 2

Frequency instability of mode-locked frequency with and without the laser control (red and black plots), and the Rb frequency standard (green plots).

Fig. 3
Fig. 3

THz detection unit. (a) bowtie-shaped LT-GaAs-PCA triggered by 775-nm, 6-mW light, (b) bowtie-shaped LT-GaAs-PCA triggered by 1550-nm, 20-mW light, (c) bowtie-shaped LT-InGaAs/InAlAs-PCA triggered by 1550-nm, 30-mW light, and (d) FSEOS of 1mm-thick ZnTe crystal probed by 775-nm, 6-mW light. AMP: high-gain current preamplifier; PL: polarizer; λ/4: quarter waveplate; RP: Rochon prism.

Fig. 4
Fig. 4

Test source for CW-THz radiation. (a) Active frequency multiplier chain (output power = 5.4 mW at 80 GHz and tuning range = 75–110 GHz) driven by a frequency synthesizer and (b) photomixing source (output power = 100 µW and output frequency = 120 GHz) of two free-running near-infrared lasers (CWL1 and CWL2) with a F-band uni-traveling-carrier photodiodes (UTC-PD).

Fig. 5
Fig. 5

Comparison of signal-to-noise ratio of the fb beat signal obtained by four THz detection units (RBW = 1 kHz and sweep rate = 43.5 kHz/s). A test source is the AFMC source with output power of 5.4 mW at frequency of 80 GHz.

Fig. 6
Fig. 6

(a) Spectra of the fb beat signal of the AFMC source measured by the RF spectrum analyzer (RBW = 1 Hz and sweep rate = 43.5 Hz/s). (b) Frequency fluctuation of the fb beat signal measured by the RF frequency counter.

Fig. 7
Fig. 7

Frequency accuracy of the AFMC source measured with the fiber-based, THz-comb-referenced spectrum analyzer (black plots) and the Ti:Sapphire-laser-based one (red plots).

Fig. 8
Fig. 8

Spectra of the fb beat signal of the AFMC source (a) without (Media 1) and (b) with the laser stabilization (Media 2). Five consecutive spectra of the beat signal were measured at 6-sec intervals. RBW = 100 Hz and sweep rate = 16.5 kHz/s.

Fig. 9
Fig. 9

Spectrum of the fb beat signal of the photomixing source (Media 3). RBW = 1 kHz and sweep rate = 75 MHz/s.

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

fTHz=mf±fb.
m=|δfb||δf|=|44,549||25|=1,781.961,782.
fTHz=mffb=1,782*56,122,206.03356,156=100,009,414,989.46Hz.

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