Abstract

We report two novel fabrication techniques, as well as THz spectral transmission and propagation loss measurements of subwavelength plastic wires with highly porous (up to 86%) and non-porous transverse geometries. The two fabrication techniques we describe are based on the microstructured molding approach. In one technique the mold is made completely from silica by stacking and fusing silica capillaries to the bottom of a silica ampoule. The melted material is then poured into the silica mold to cast the microstructured preform. Another approach uses a microstructured mold made of a sacrificial plastic which is co-drawn with a cast preform. Material from the sacrificial mold is then dissolved after fiber drawing. We also describe a novel THz-TDS setup with an easily adjustable optical path length, designed to perform cutback measurements using THz fibers of up to 50 cm in length. We find that while both porous and non-porous subwavelength fibers of the same outside diameter have low propagation losses (α ≤ 0.02 cm−1), the porous fibers exhibit a much wider spectral transmission window and enable transmission at higher frequencies compared to the non-porous fibers.

© 2010 OSA

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  1. M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
    [CrossRef]
  2. K. Wang, and M. Mittleman, “Metal wires for terahertz wave guiding,” Nature 432, 376–379 (2004).
    [CrossRef] [PubMed]
  3. L.-J. Chen, H.-W. Chen, T.-F. Kao, J.-Y. Lu, and C.-K. Sun, “Low-loss subwavelength plastic fiber for terahertz waveguiding,” Opt. Lett. 31(3), 306–308 (2006).
    [CrossRef]
  4. Q. Cao, and J. Jahns, “Azimuthally polarized surface plasmons as effective terahertz waveguides,” Opt. Express 13(2), 511–518 (2005).
    [CrossRef] [PubMed]
  5. T.-I. Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Lett. 86, 161904 (2005).
    [CrossRef]
  6. J. A. Deibel, K. Wang, M. D. Escarra, and D. M. Mittleman, “Enhanced coupling of terahertz radiation to cylindrical wire waveguides,” Opt. Express 14(1), 279–290 (2006).
    [CrossRef] [PubMed]
  7. V. Astley, J. Scheiman, R. Mendis, and D. M. Mittleman, “Bending and coupling losses in terahertz wire waveguides,” Opt. Lett. 35(4), 53–555 (2010).
    [CrossRef]
  8. M. Mbonye, R. Mendis, and D. M. Mittleman, “A terahertz two-wire waveguide with low bending loss,” Appl. Phys. Lett. 95, 233506 (2009).
    [CrossRef]
  9. H.-W. Chen, Y.-T. Li, C.-L. Pan, J.-L. Kuo, J.-Y. Lu, L.-J. Chen, and C.-K. Sun, “Investigation on spectral loss characteristics of subwavelength terahertz fibers,” Opt. Lett. 32(9), 1017–1019 (2007).
    [CrossRef] [PubMed]
  10. J.-Y. Lu, C.-C. Kuo, C.-M. Chiu, H.-W. Chen, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “THz interferometric imaging using subwavelength plastic fiber based THz endoscopes,” Opt. Express 16, 2494–2501 (2008).
    [CrossRef] [PubMed]
  11. J.-Y. Lu, C.-M. Chiu, C.-C. Kuo, C.-H. Lai, H.-C. Chang, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “Terahertz scanning imaging with a subwavelength plastic fiber,” Appl. Phys. Lett. 92, 084102 (2008).
    [CrossRef]
  12. A. Dupuis, J.-F. Allard, D. Morris, K. Stoeffler, C. Dubois, and M. Skorobogatiy, “Fabrication and THz loss measurements of porous subwavelength fibers using a directional coupler method,” Opt. Express 17, 8012–8028 (2009).
    [CrossRef] [PubMed]
  13. B. You, T.-A. Liu, J.-L. Peng, C.-L. Pan, and J.-Y. Lu, “A terahertz plastic wire based evanescent field sensor for high sensitivity liquid detection,” Opt. Express 17(23), 20675–20683 (2009).
    [CrossRef] [PubMed]
  14. C.-M. Chiu, H.-W. Chen, Y.-R. Huang, Y.-J. Hwang, W.-J. Lee, H.-Y. Huang, and C.-K. Sun, “All-terahertz fiber-scanning near-field microscopy,” Opt. Lett. 34(7), 1084–1086 (2009).
    [CrossRef] [PubMed]
  15. A. Hassani, A. Dupuis, and M. Skorobogatiy, “Low loss porous terahertz fibers containing multiple subwavelength holes,” Appl. Phys. Lett. 92, 071101 (2008).
    [CrossRef]
  16. A. Hassani, A. Dupuis, and M. Skorobogatiy, “Porous polymer fibers for low-loss Terahertz guiding,” Opt. Express 16(9), 6340–6351 (2008).
    [CrossRef] [PubMed]
  17. S. Atakaramians, S. Afshar, B. M. Fischer, D. Abbott, and T. M. Munro, “Porous Fibers: a novel approach to low loss THz waveguides,” Opt. Express 16(12), 8845–8854 (2008).
    [CrossRef] [PubMed]
  18. R. Mendis, and D. Grischkowsky, “Undistorted guided-wave propagation of subpicosecond terahertz pulses,” Opt. Lett. 26, 846 (2001).
    [CrossRef]
  19. M. Nagel, A. Marchewka, and H. Kurz, “Low-index discontinuity terahertz waveguides,” Opt. Express 14(21), 9944–9954 (2006).
    [CrossRef] [PubMed]
  20. C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
    [CrossRef]
  21. K. Nielsen, H. K. Rasmussen, A. J. Adam, P. C. Planken, O. Bang, and P. U. Jepsen, “Bendable, low-loss Topas fibers for the terahertz frequency range,” Opt. Express 17, 8592–8601 (2009).
    [CrossRef] [PubMed]
  22. S. Atakaramians, S. Afshar Vihad, H. Ebendorff-Heidepriem, M. Nagel, B. M. Fischer, D. Abbott, and T. M. Monro, “THz porous fibers: design, fabrication and experimental characterization,” Opt. Express 17, 14053 (2009).
    [CrossRef] [PubMed]
  23. S. G. Johnson, M. Ibanescu, M. Skorobogatiy, O. Weiseberg, T. D. Engeness, M. Soljacic, S. A. Jacobs, J. D. Joannopoulos, and Y. Fink, “Low-Loss Asymptotically Single-Mode Propagation in Large Core OmniGuide Fibers,” Opt. Express 9, 748–779 (2001).
    [CrossRef] [PubMed]
  24. A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
    [CrossRef]
  25. Y.-S. Jin, G.-J. Kim, and S.-Y. Jeon, “Terahertz Dielectric Properties of Polymers,” J. Korean Phys. Soc. 49, 513–517 (2006).

2010 (1)

V. Astley, J. Scheiman, R. Mendis, and D. M. Mittleman, “Bending and coupling losses in terahertz wire waveguides,” Opt. Lett. 35(4), 53–555 (2010).
[CrossRef]

2009 (6)

2008 (6)

A. Hassani, A. Dupuis, and M. Skorobogatiy, “Low loss porous terahertz fibers containing multiple subwavelength holes,” Appl. Phys. Lett. 92, 071101 (2008).
[CrossRef]

A. Hassani, A. Dupuis, and M. Skorobogatiy, “Porous polymer fibers for low-loss Terahertz guiding,” Opt. Express 16(9), 6340–6351 (2008).
[CrossRef] [PubMed]

S. Atakaramians, S. Afshar, B. M. Fischer, D. Abbott, and T. M. Munro, “Porous Fibers: a novel approach to low loss THz waveguides,” Opt. Express 16(12), 8845–8854 (2008).
[CrossRef] [PubMed]

J.-Y. Lu, C.-C. Kuo, C.-M. Chiu, H.-W. Chen, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “THz interferometric imaging using subwavelength plastic fiber based THz endoscopes,” Opt. Express 16, 2494–2501 (2008).
[CrossRef] [PubMed]

J.-Y. Lu, C.-M. Chiu, C.-C. Kuo, C.-H. Lai, H.-C. Chang, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “Terahertz scanning imaging with a subwavelength plastic fiber,” Appl. Phys. Lett. 92, 084102 (2008).
[CrossRef]

C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
[CrossRef]

2007 (2)

2006 (5)

L.-J. Chen, H.-W. Chen, T.-F. Kao, J.-Y. Lu, and C.-K. Sun, “Low-loss subwavelength plastic fiber for terahertz waveguiding,” Opt. Lett. 31(3), 306–308 (2006).
[CrossRef]

J. A. Deibel, K. Wang, M. D. Escarra, and D. M. Mittleman, “Enhanced coupling of terahertz radiation to cylindrical wire waveguides,” Opt. Express 14(1), 279–290 (2006).
[CrossRef] [PubMed]

M. Nagel, A. Marchewka, and H. Kurz, “Low-index discontinuity terahertz waveguides,” Opt. Express 14(21), 9944–9954 (2006).
[CrossRef] [PubMed]

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

Y.-S. Jin, G.-J. Kim, and S.-Y. Jeon, “Terahertz Dielectric Properties of Polymers,” J. Korean Phys. Soc. 49, 513–517 (2006).

2005 (2)

Q. Cao, and J. Jahns, “Azimuthally polarized surface plasmons as effective terahertz waveguides,” Opt. Express 13(2), 511–518 (2005).
[CrossRef] [PubMed]

T.-I. Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Lett. 86, 161904 (2005).
[CrossRef]

2004 (1)

K. Wang, and M. Mittleman, “Metal wires for terahertz wave guiding,” Nature 432, 376–379 (2004).
[CrossRef] [PubMed]

2001 (2)

Abbott, D.

Adam, A. J.

Afshar, S.

Afshar Vihad, S.

Allard, J.-F.

Astley, V.

V. Astley, J. Scheiman, R. Mendis, and D. M. Mittleman, “Bending and coupling losses in terahertz wire waveguides,” Opt. Lett. 35(4), 53–555 (2010).
[CrossRef]

Atakaramians, S.

Bandyopadhyay, A.

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

Bang, O.

Bowden, B. F.

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

Cao, Q.

Chang, H.-C.

J.-Y. Lu, C.-M. Chiu, C.-C. Kuo, C.-H. Lai, H.-C. Chang, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “Terahertz scanning imaging with a subwavelength plastic fiber,” Appl. Phys. Lett. 92, 084102 (2008).
[CrossRef]

Chen, H.-W.

Chen, L.-J.

H.-W. Chen, Y.-T. Li, C.-L. Pan, J.-L. Kuo, J.-Y. Lu, L.-J. Chen, and C.-K. Sun, “Investigation on spectral loss characteristics of subwavelength terahertz fibers,” Opt. Lett. 32(9), 1017–1019 (2007).
[CrossRef] [PubMed]

L.-J. Chen, H.-W. Chen, T.-F. Kao, J.-Y. Lu, and C.-K. Sun, “Low-loss subwavelength plastic fiber for terahertz waveguiding,” Opt. Lett. 31(3), 306–308 (2006).
[CrossRef]

Chiu, C.-M.

Deibel, J. A.

Dubois, C.

Dupuis, A.

Ebendorff-Heidepriem, H.

Engeness, T. D.

Escarra, M. D.

Fan, D.

C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
[CrossRef]

Federici, J. F.

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

Fink, Y.

Fischer, B. M.

Grischkowsky, D.

T.-I. Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Lett. 86, 161904 (2005).
[CrossRef]

R. Mendis, and D. Grischkowsky, “Undistorted guided-wave propagation of subpicosecond terahertz pulses,” Opt. Lett. 26, 846 (2001).
[CrossRef]

Harrington, J. A.

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

Hassani, A.

A. Hassani, A. Dupuis, and M. Skorobogatiy, “Porous polymer fibers for low-loss Terahertz guiding,” Opt. Express 16(9), 6340–6351 (2008).
[CrossRef] [PubMed]

A. Hassani, A. Dupuis, and M. Skorobogatiy, “Low loss porous terahertz fibers containing multiple subwavelength holes,” Appl. Phys. Lett. 92, 071101 (2008).
[CrossRef]

Huang, H.-Y.

Huang, Y.-R.

Hwang, Y.-J.

Ibanescu, M.

Jacobs, S. A.

Jahns, J.

Jeon, S.-Y.

Y.-S. Jin, G.-J. Kim, and S.-Y. Jeon, “Terahertz Dielectric Properties of Polymers,” J. Korean Phys. Soc. 49, 513–517 (2006).

Jeon, T.-I.

T.-I. Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Lett. 86, 161904 (2005).
[CrossRef]

Jepsen, P. U.

Jin, Y.-S.

Y.-S. Jin, G.-J. Kim, and S.-Y. Jeon, “Terahertz Dielectric Properties of Polymers,” J. Korean Phys. Soc. 49, 513–517 (2006).

Joannopoulos, J. D.

Johnson, S. G.

Kao, T.-F.

L.-J. Chen, H.-W. Chen, T.-F. Kao, J.-Y. Lu, and C.-K. Sun, “Low-loss subwavelength plastic fiber for terahertz waveguiding,” Opt. Lett. 31(3), 306–308 (2006).
[CrossRef]

Kim, G.-J.

Y.-S. Jin, G.-J. Kim, and S.-Y. Jeon, “Terahertz Dielectric Properties of Polymers,” J. Korean Phys. Soc. 49, 513–517 (2006).

Kuo, C.-C.

J.-Y. Lu, C.-C. Kuo, C.-M. Chiu, H.-W. Chen, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “THz interferometric imaging using subwavelength plastic fiber based THz endoscopes,” Opt. Express 16, 2494–2501 (2008).
[CrossRef] [PubMed]

J.-Y. Lu, C.-M. Chiu, C.-C. Kuo, C.-H. Lai, H.-C. Chang, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “Terahertz scanning imaging with a subwavelength plastic fiber,” Appl. Phys. Lett. 92, 084102 (2008).
[CrossRef]

Kuo, J.-L.

Kurz, H.

Lai, C.-H.

J.-Y. Lu, C.-M. Chiu, C.-C. Kuo, C.-H. Lai, H.-C. Chang, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “Terahertz scanning imaging with a subwavelength plastic fiber,” Appl. Phys. Lett. 92, 084102 (2008).
[CrossRef]

Lee, W.-J.

Li, Y.-T.

Liu, T.-A.

Lu, J.-Y.

Marchewka, A.

Mbonye, M.

M. Mbonye, R. Mendis, and D. M. Mittleman, “A terahertz two-wire waveguide with low bending loss,” Appl. Phys. Lett. 95, 233506 (2009).
[CrossRef]

Mendis, R.

V. Astley, J. Scheiman, R. Mendis, and D. M. Mittleman, “Bending and coupling losses in terahertz wire waveguides,” Opt. Lett. 35(4), 53–555 (2010).
[CrossRef]

M. Mbonye, R. Mendis, and D. M. Mittleman, “A terahertz two-wire waveguide with low bending loss,” Appl. Phys. Lett. 95, 233506 (2009).
[CrossRef]

R. Mendis, and D. Grischkowsky, “Undistorted guided-wave propagation of subpicosecond terahertz pulses,” Opt. Lett. 26, 846 (2001).
[CrossRef]

Mittleman, D. M.

V. Astley, J. Scheiman, R. Mendis, and D. M. Mittleman, “Bending and coupling losses in terahertz wire waveguides,” Opt. Lett. 35(4), 53–555 (2010).
[CrossRef]

M. Mbonye, R. Mendis, and D. M. Mittleman, “A terahertz two-wire waveguide with low bending loss,” Appl. Phys. Lett. 95, 233506 (2009).
[CrossRef]

J. A. Deibel, K. Wang, M. D. Escarra, and D. M. Mittleman, “Enhanced coupling of terahertz radiation to cylindrical wire waveguides,” Opt. Express 14(1), 279–290 (2006).
[CrossRef] [PubMed]

Mittleman, M.

K. Wang, and M. Mittleman, “Metal wires for terahertz wave guiding,” Nature 432, 376–379 (2004).
[CrossRef] [PubMed]

Monro, T. M.

Morris, D.

Munro, T. M.

Nagel, M.

Nielsen, K.

Pan, C.-L.

Peng, J.-L.

Planken, P. C.

Rasmussen, H. K.

Scheiman, J.

V. Astley, J. Scheiman, R. Mendis, and D. M. Mittleman, “Bending and coupling losses in terahertz wire waveguides,” Opt. Lett. 35(4), 53–555 (2010).
[CrossRef]

Sengupta, A.

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

Skorobogatiy, M.

Soljacic, M.

Stoeffler, K.

Sun, C.-K.

Tonouchi, M.

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
[CrossRef]

Wang, K.

Weiseberg, O.

Wen, S.

C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
[CrossRef]

Wu, M.

C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
[CrossRef]

You, B.

Zhang, J.

T.-I. Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Lett. 86, 161904 (2005).
[CrossRef]

Zhao, C.

C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
[CrossRef]

Appl. Phys. Lett. (4)

T.-I. Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Lett. 86, 161904 (2005).
[CrossRef]

M. Mbonye, R. Mendis, and D. M. Mittleman, “A terahertz two-wire waveguide with low bending loss,” Appl. Phys. Lett. 95, 233506 (2009).
[CrossRef]

J.-Y. Lu, C.-M. Chiu, C.-C. Kuo, C.-H. Lai, H.-C. Chang, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “Terahertz scanning imaging with a subwavelength plastic fiber,” Appl. Phys. Lett. 92, 084102 (2008).
[CrossRef]

A. Hassani, A. Dupuis, and M. Skorobogatiy, “Low loss porous terahertz fibers containing multiple subwavelength holes,” Appl. Phys. Lett. 92, 071101 (2008).
[CrossRef]

Electron. Lett. (1)

A. Sengupta, A. Bandyopadhyay, B. F. Bowden, J. A. Harrington, and J. F. Federici, “Characterisation of olefin copolymers using terahertz spectroscopy,” Electron. Lett. 42(25), (2006).
[CrossRef]

J. Korean Phys. Soc. (1)

Y.-S. Jin, G.-J. Kim, and S.-Y. Jeon, “Terahertz Dielectric Properties of Polymers,” J. Korean Phys. Soc. 49, 513–517 (2006).

Nat. Photonics (1)

M. Tonouchi, “Cutting-edge terahertz technology,” Nat. Photonics 1, 97–105 (2007).
[CrossRef]

Nature (1)

K. Wang, and M. Mittleman, “Metal wires for terahertz wave guiding,” Nature 432, 376–379 (2004).
[CrossRef] [PubMed]

Opt. Commun. (1)

C. Zhao, M. Wu, D. Fan, and S. Wen, “Field enhancement and power distribution characteristics of subwavelength-diameter terahertz hollow optical fiber,” Opt. Commun. 281, 11291133 (2008).
[CrossRef]

Opt. Express (11)

K. Nielsen, H. K. Rasmussen, A. J. Adam, P. C. Planken, O. Bang, and P. U. Jepsen, “Bendable, low-loss Topas fibers for the terahertz frequency range,” Opt. Express 17, 8592–8601 (2009).
[CrossRef] [PubMed]

S. Atakaramians, S. Afshar Vihad, H. Ebendorff-Heidepriem, M. Nagel, B. M. Fischer, D. Abbott, and T. M. Monro, “THz porous fibers: design, fabrication and experimental characterization,” Opt. Express 17, 14053 (2009).
[CrossRef] [PubMed]

S. G. Johnson, M. Ibanescu, M. Skorobogatiy, O. Weiseberg, T. D. Engeness, M. Soljacic, S. A. Jacobs, J. D. Joannopoulos, and Y. Fink, “Low-Loss Asymptotically Single-Mode Propagation in Large Core OmniGuide Fibers,” Opt. Express 9, 748–779 (2001).
[CrossRef] [PubMed]

M. Nagel, A. Marchewka, and H. Kurz, “Low-index discontinuity terahertz waveguides,” Opt. Express 14(21), 9944–9954 (2006).
[CrossRef] [PubMed]

J. A. Deibel, K. Wang, M. D. Escarra, and D. M. Mittleman, “Enhanced coupling of terahertz radiation to cylindrical wire waveguides,” Opt. Express 14(1), 279–290 (2006).
[CrossRef] [PubMed]

Q. Cao, and J. Jahns, “Azimuthally polarized surface plasmons as effective terahertz waveguides,” Opt. Express 13(2), 511–518 (2005).
[CrossRef] [PubMed]

J.-Y. Lu, C.-C. Kuo, C.-M. Chiu, H.-W. Chen, Y.-J. Hwang, C.-L. Pan, and C.-K. Sun, “THz interferometric imaging using subwavelength plastic fiber based THz endoscopes,” Opt. Express 16, 2494–2501 (2008).
[CrossRef] [PubMed]

A. Hassani, A. Dupuis, and M. Skorobogatiy, “Porous polymer fibers for low-loss Terahertz guiding,” Opt. Express 16(9), 6340–6351 (2008).
[CrossRef] [PubMed]

S. Atakaramians, S. Afshar, B. M. Fischer, D. Abbott, and T. M. Munro, “Porous Fibers: a novel approach to low loss THz waveguides,” Opt. Express 16(12), 8845–8854 (2008).
[CrossRef] [PubMed]

A. Dupuis, J.-F. Allard, D. Morris, K. Stoeffler, C. Dubois, and M. Skorobogatiy, “Fabrication and THz loss measurements of porous subwavelength fibers using a directional coupler method,” Opt. Express 17, 8012–8028 (2009).
[CrossRef] [PubMed]

B. You, T.-A. Liu, J.-L. Peng, C.-L. Pan, and J.-Y. Lu, “A terahertz plastic wire based evanescent field sensor for high sensitivity liquid detection,” Opt. Express 17(23), 20675–20683 (2009).
[CrossRef] [PubMed]

Opt. Lett. (5)

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Figures (6)

Fig. 1.
Fig. 1.

Tunable THz-TDS setup for waveguide transmission measurements. a) Schematic of setup. E:Emitter, D:Detector, PM:Parabolic Mirror, BS:Beam Splitter, FM: Flat Mirror, b) Source spectrum (red) and background noise level (blue). There are traces of water vapor (black) despite efforts to purge with a nitrogen atmosphere. c), d) Photographs of a setup for different positions of the mirror assembly that allows to either perform measurements of a point sample c) or to accommodate a waveguide up to 50 cm in length d).

Fig. 2.
Fig. 2.

Schematics of various subwavelength fibers and their fabrication techniques. a)-c) Poynting vector distributions across fiber cross-sections for subwavelength fibers featuring 0, 1, and 7 holes, respectively. The outer diameter of all the fibers is 400µm, the diameter of all the holes is 100µm, and the frequency is 0.3 THz (λ = 1000µm). Schematics of the d) sacrificial polymer technique and e) microstructured molding technique for fabricating porous subwavelength fibers.

Fig. 3.
Fig. 3.

Transmission and loss measurements of porous and non-porous subwavelength PE fibers. Left column: small diameter fibers, Right column: large diameter fibers. The data for the porous fibers is in red and data for the non-porous fibers is in blue. Fiber diameters and measured segments lengths are indicated in the legends. Photos a) and e) show measured fiber cross-sections; b) and f) Normalized amplitude transmission; c) and g) Power propagation loss calculated from the transmission spectra using cutback technique; d) and h) Upper bound on propagation loss given by normalized (per unit of unit of length) total loss.

Fig. 4.
Fig. 4.

Modal losses of the porous and non-porous fibers as a function of the fiber geometry parameters (dF = fiber diameter, P = porosity). First row: non-porous subwavelength fiber; second row: subwavelength fiber with 7 air holes; third row: subwavelength fiber with one air hole. First column: schematics of the fiber geometries; second column: fundamental modal attenuation loss as a function of frequency; third column: power coupling coefficient between a gaussian beam and the fundamental mode.

Fig. 5.
Fig. 5.

Theoretical calculations of the dispersion parameter of non-porous (a) and porous (b) fibers. The effective index curves of the non-porous and porous fibers were taken from the simulations presented in Figs. 3.b) and 3.e), respectively. Decrease of the fiber diameter and increase of the porosity result in the reduction of dispersion. Comparison of the time scans of ~450 µm diameter porous (red curve) and non-porous (blue curve) fibers confirms that dispersion is smaller in porous fibers because the length of the dispersed THz pulse is shorter (envelope is decaying faster). The porous fiber time scan is offset vertically and the reference pulse of the source is scaled a factor 1/40 for clarity.

Fig. 6.
Fig. 6.

Theoretical fit of transmission spectra through large and small diameter subwavelength fibers. The theoretical fits (solid lines) take into account coupling loss (dotted lines) and absorption loss (dashed lines) contributions but neglect scattering losses. The calculations assumed αmat = 0.2cm−1, a porosity of 35% for the small diameter fiber, and a porosity of 72% for the large diameter fiber. Optimal fits for the non-porous fibers were found for diameters slightly different from the experimentally measured diameters.

Equations (4)

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E waveguide ( ω ) = E source ( ω ) · η · C in · C out · e i [ ω c ( n eff L w ) + ω c ( L path 2 L w ) ] e α L w 2 ,
E reference ( ω ) = E source ( ω ) · η · e i ω c L path 2 ,
T ( ω , L w ) = E waveguide ( ω ) E reference ( ω ) = C in · C out · e i ( n eff 1 ) ( ω c ) L w e α L w 2 ,
T ( ω , L 2 ) T ( ω , L 1 ) = E waveguide ( ω , L 2 ) E reference ( 2 ) ( ω ) · E reference ( 1 ) ( ω ) E waveguide ( ω , L 1 ) = e α ( L 2 L 1 ) 2 ,

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