Ultra-broadband field-resolved detection using photoconductive antenna from sub-THz to near-infrared

Abstract

The field-resolved detection of infrared (IR) waves is a powerful method for ultrafast spectroscopy; the extension of its bandwidth has made rapid progress [1]. Photoconductive (PC) antenna, which detects photocurrent induced by incident electric field gated with ultra-short laser pulses, is widely used along with electro-optic sampling. We have demonstrated ultra-broadband detection from 0.1 to 100 THz with one dipoletype PC antenna using probe pulses of 10 fs duration and a PC antenna emitter (black curve in Fig. 1) or a thin GaSe crystal (blue curve in Fig. 1) [2]. Surprisingly, we recently succeeded in ultra-high frequency detection up to 170 THz (red curve in Fig. 1) with the PC antenna using a combination of extremely short pulses with the duration of approximately 5 fs and a DAST (4-dimethylamino-N-methyl-4-stilbazollium tosylate) crystal [3].