Optical properties and potential applications of ε-GaSe at terahertz frequencies

Ching Wei Chen, Tsung Ta Tang, Sung Hui Lin, Jung Y. Huang, Chen Shiung Chang, Pei Kang Chung, Shun-Tung Yen, Ci Ling Pan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


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 (FOM ∼ 103 at 1 THz), the large birefringence (δn ∼ 0.76 at 1 THz). and the low absorption coefficient (α ∼ 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.

Original languageEnglish
JournalJournal of the Optical Society of America B: Optical Physics
Issue number9
StatePublished - 1 Sep 2009

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