Indium-tin-oxide nanowhiskers were employed as transparent electrodes in a liquid-crystal terahertz phase shifter. Transmittance of the device was as high as ∼75%. Phase shift exceeding π/2 at 1.0 THz is achieved in a ∼500  μm-thick cell. The driving voltage required for the device operating as a quarter-wave plate was as low as 17.68 V (rms), an improvement of nearly an order of magnitude over previous work.

Ordinary and extraordinary refractive indices of an ε-GaSe crystal at terahertz (THz) frequencies are experimentally determined in this study. Fitting experimental data by THz time-domain spectroscopy (THz-TDS) and a Fourier transform infrared spectrometer (FTIR), we proposed revised complex dielectric functions and Sellmeier equations of GaSe for both ordinary and extraordinary waves from 0.2 to 100 THz. Phonon vibrational modes and overtones in the THz frequency range are examined in detail. The high magnitude of the figure of merit (FOMϳ 10 3 at 1 THz), the large birefringence (⌬n ϳ 0.76 at 1 THz). and the low absorption coefficient (␣ ϳ 0.2 cm −1 at 1 THz) of GaSe are also identified. Potential applications to practical photonic devices such as phase shifters at THz frequencies are proposed.

Indium Tin Oxide (ITO) nanowhiskers (NWhs) obliquely evaporated by electron-beam glancingangle deposition can serve simultaneously as transparent electrodes and alignment layer for liquid crystal (LC) devices in the terahertz (THz) frequency range. To demonstrate, we constructed a THz LC phase shifter with ITO NWhs. Phase shift exceeding p/2 at 1.0 THz was achieved in a $517 lmthick cell. The phase shifter exhibits high transmittance ($78%). The driving voltage required for quarter-wave operation is as low as 5.66 V (rms), compatible with complementary metal-oxidesemiconductor (CMOS) and thin-film transistor (TFT) technologies. V

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