3.5 Summary
67
other polarimetry or ellipsometry methods. This approach allows broadband polarization rotation, with linearly polarized THz pulses that can be rotated to arbitrary
angles (accuracy < 1.0
◦ , precision < 0.1
◦ ) over a frequency range of 0.3–2.5 THz.
The optimisation of the setup was reported, resulting in a variation in amplidude of
only ∼ 7% over the 180
◦ range of the device, and the polarisation state exhibits only
a very small intrinsic ellipticity (accuracy < 0.75
◦ , precision < 0.1
◦ ). This method
of polarisation rotation was also shown to perform favourably compared to WGPs,
which were shown to introduce large variations in the polarisation state of projected
THz pulses.
RP-THz-TDS was also experimentally implemented, demonstrating how the technique may be used to identify the in-plane polarisation eigenvectors of birefringent
materials, and to determine the full complex refractive index along each of these
directions. A demonstration of how RP-THz-TDS may be used to investigate the
selection rules of an anisotropic absorption feature was also provided, by studying
the electromagnon absorption in CuO.
The polarisation rotation method presented here does not require WGPs, circumventing the problem of their poor extinction ratio, and is performed during the
generation of the THz pulses, avoiding reflection losses associated with transmissive
components like wave plates. Rotating the THz polarization state not only allows
convenient access to the anisotropic optical properties at cryogenic temperatures or
other situations in which rotating the sample may be challenging, but also ensures
that the same area on the sample is probed at each angle, solving many issues related
to rotating the sample.
References
1. Lloyd-Hughes J, Jones SPP, Castro-Camus E, Doig KI, MacManus-Driscoll JL (2014) Optics
letters 39:1121
2. Azzam RMA, Bashara NM, Ballard SS (1978) Physics Today 31:72
3. Fujiwara H (2007) Spectroscopic ellipsometry : principles and applications. John Wiley &
Sons
4. Kim Y, Yi M, Kim BG, Ahn J (2011) Applied Optics 50:2906
5. Wiesauer K, Jördens C (2013) Journal of Infrared. Millimeter, and Terahertz Waves 34:663
6. C. M. Morris, R. V. Aguilar, A. V. Stier, and N. P. Armitage, Optics Express, Vol. 20, Issue 11,
pp. 12303-12317 20, 12303 (2012)
7. Nagashima T, Tani M, Hangyo M (2013) Journal of Infrared. Millimeter, and Terahertz Waves
34:740
8. Kuhne P et al (2018) IEEE Transactions on Terahertz Science and Technology 8:257
9. Yamada I, Takano K, Hangyo M, Saito M, Watanabe W (2009) Optics Letters 34:274
10. Morikawa O et al (1999) Applied Physics Letters 75:3387
11. Morikawa O et al (2006) Journal of Applied Physics 100:033105
12. Palik ED, Furdyna JK (1970) Reports on Progress in Physics 33:307
13. Castro-Camus E et al (2005) Applied Physics Letters 86:3
14. Castro-Camus E et al (2007) Optics Express 15:7047
15. Makabe H, Hirota Y, Tani M, Hangyo M (2007) Opt. Express 15:11650
16. Neshat M, Armitage NP (2012) Optics Letters 37:1811
67
other polarimetry or ellipsometry methods. This approach allows broadband polarization rotation, with linearly polarized THz pulses that can be rotated to arbitrary
angles (accuracy < 1.0
◦ , precision < 0.1
◦ ) over a frequency range of 0.3–2.5 THz.
The optimisation of the setup was reported, resulting in a variation in amplidude of
only ∼ 7% over the 180
◦ range of the device, and the polarisation state exhibits only
a very small intrinsic ellipticity (accuracy < 0.75
◦ , precision < 0.1
◦ ). This method
of polarisation rotation was also shown to perform favourably compared to WGPs,
which were shown to introduce large variations in the polarisation state of projected
THz pulses.
RP-THz-TDS was also experimentally implemented, demonstrating how the technique may be used to identify the in-plane polarisation eigenvectors of birefringent
materials, and to determine the full complex refractive index along each of these
directions. A demonstration of how RP-THz-TDS may be used to investigate the
selection rules of an anisotropic absorption feature was also provided, by studying
the electromagnon absorption in CuO.
The polarisation rotation method presented here does not require WGPs, circumventing the problem of their poor extinction ratio, and is performed during the
generation of the THz pulses, avoiding reflection losses associated with transmissive
components like wave plates. Rotating the THz polarization state not only allows
convenient access to the anisotropic optical properties at cryogenic temperatures or
other situations in which rotating the sample may be challenging, but also ensures
that the same area on the sample is probed at each angle, solving many issues related
to rotating the sample.
References
1. Lloyd-Hughes J, Jones SPP, Castro-Camus E, Doig KI, MacManus-Driscoll JL (2014) Optics
letters 39:1121
2. Azzam RMA, Bashara NM, Ballard SS (1978) Physics Today 31:72
3. Fujiwara H (2007) Spectroscopic ellipsometry : principles and applications. John Wiley &
Sons
4. Kim Y, Yi M, Kim BG, Ahn J (2011) Applied Optics 50:2906
5. Wiesauer K, Jördens C (2013) Journal of Infrared. Millimeter, and Terahertz Waves 34:663
6. C. M. Morris, R. V. Aguilar, A. V. Stier, and N. P. Armitage, Optics Express, Vol. 20, Issue 11,
pp. 12303-12317 20, 12303 (2012)
7. Nagashima T, Tani M, Hangyo M (2013) Journal of Infrared. Millimeter, and Terahertz Waves
34:740
8. Kuhne P et al (2018) IEEE Transactions on Terahertz Science and Technology 8:257
9. Yamada I, Takano K, Hangyo M, Saito M, Watanabe W (2009) Optics Letters 34:274
10. Morikawa O et al (1999) Applied Physics Letters 75:3387
11. Morikawa O et al (2006) Journal of Applied Physics 100:033105
12. Palik ED, Furdyna JK (1970) Reports on Progress in Physics 33:307
13. Castro-Camus E et al (2005) Applied Physics Letters 86:3
14. Castro-Camus E et al (2007) Optics Express 15:7047
15. Makabe H, Hirota Y, Tani M, Hangyo M (2007) Opt. Express 15:11650
16. Neshat M, Armitage NP (2012) Optics Letters 37:1811