[12p-PA1-1~18] 3.9 Terahertz technologies

[12p-PA1-17] Improvement of Calculation Procedure for Low-Cost Type sub-THz Spectrometer

〇Osamu Morikawa¹, Dai Hamada¹, Kohji Yamamoto², Kazuyoshi Kurihara², Fumiyoshi Kuwashima³, Masahiko Tani² (1.JCGA, 2.Univ. Fukui, 3.FUT)

Keywords:window function, THz wave, MLD-TDS

The terahertz time-domain spectroscopic system (THz-TDS) is a powerful instrument, which can measure both transmittance and phase shift caused by samples. The THz-TDS usually employs a femtosecond pulse laser, which enhances the system cost. Previously we proposed using a multimode laser diode (MLD) instead of the femtosecond pulse laser to reduce the system cost. The signal spectrum was discrete even if we employ a broad-area laser diode, which shows quasi-dense optical spectrum. We successfully make the signal spectrum continuous by using a single-mode optical fiber or a spatial filter. In this study, we apply this low-cost type THz-TDS to the characterization of polymer samples. Then we found sinusoidal structures in the obtained complex refractive index when the sample is optically thick one, the insertion of which causes elongation of the optical path by as long as 7.5 mm. We consider the origin of the sinusoidal structure and improvement of the calculation procedure to remove the sinusoidal structure.