Physikalische Chemie - Direktor: Prof. Dr. Martin Wolf
Special Seminar
Host: Aki Shiotari

Friday, August 25, 2023, 11:00 am
All are invited to meet around 10:40 am for a chat with coffee & cookies.
PC Seminar Room, G 2.06, Faradayweg 4
Shunsuke Tanaka
ISSP, University of Tokyo
Gapless Detection of Broadband Terahertz Pulses Using a Metal Surface in Air-based on Field-induced Second-harmonic Generation
We investigate second-harmonic generation (SHG) light from a Pt surface in air under terahertz (THz) pulse irradiation. THz pulse-modulated SHG intensity shows a clear time profile of the THz field. The result can be explained by interference between THz field-induced second-harmonic light from air molecules in an optical path and a local oscillator from a Pt surface, whereby heterodyne detection of the THz waveform can be achieved. Using numerical calculations of a wave equation, we discuss the contribution of the Gouy phases of all the pulses, including near-infrared, SHG, and THz pulses. Our method, simply using a polished metal surface and air molecules, does not suffer from phonons or phase matching in solid-state optics and does not require any power supply, bias voltage, or fabrication process, but it offers a simple and gapless sampling method for broadband THz pulses. Here, we demonstrate the gapless detection of a broadband THz pulse in the region of 0.2–20 THz using this method and named it the air-metal coherent detection (AMCD) method [1].
[1] S. Tanaka et al., Applied Physics Letters 122, 251101 (2023).