Metal-Coated <100>-Cut GaAs Coupled to Tapered Parallel-Plate Waveguide for Cherenkov-Phase-Matched Terahertz Detection: Influence of Crystal Thickness

• Main Authors: Delos Santos, Ramon M, Mag-usara, Valynn Katrine, Tuico, Anthony, Copa, Vernalyn, Salvador, Arnel, Yamamoto, Kohji, Somintac, Armando S, Kurihara, Kazuyoshi, Kitahara, Hideaki, Tani, Masahiko, Estacio, Elmer S
• Format: text
• Published: Archīum Ateneo 2018
• Subjects: Terahertz waves; Electro-optic sampling; Cherenkov-phase-matching; Gallium arsenide; Waveguide; Atomic, Molecular and Optical Physics; Physics
• Online Access: https://archium.ateneo.edu/physics-faculty-pubs/53; https://link.springer.com/article/10.1007/s10762-018-0487-1
• Institution: Ateneo De Manila University

The influence of crystal thickness of metal-coated <100>-cut GaAs (M-G-M) on Cherenkov-phase-matched terahertz (THz) pulse detection was studied. The M-G-M detectors were utilized in conjunction with a metallic tapered parallel-plate waveguide (TPPWG). Polarization-sensitive measurements were carried out to exemplify the efficacy of GaAs in detecting transverse magnetic (TM)- and transverse electric (TE)-polarized THz waves. The reduction of GaAs’ thickness increased the THz amplitude spectra of the detected TM-polarized THz electro-optic (EO) signal due to enhanced electric field associated with a more tightly-focused and well-concentrated THz radiation on the thinner M-G-M. The higher-fluence THz beam coupled to the thinner M-G-M improved the integrated intensity of the detected THz amplitude spectrum. This trend was not observed for TE-polarized THz waves, wherein the integrated intensities were almost comparable. Nevertheless, good agreement of spectral line shapes of the superposed TM- and TE-polarized THz-EO signals with that of elliptically polarized THz-EO signal demonstrates excellent polarization-resolved detection capabilities of M-G-M via Cherenkov-phase-matched EO sampling technique.