[19p-Z06-1~12] 3.6 Ultrashort-pulse and high-intensity lasers

▲ [19p-Z06-9] Background-Free Absorption Spectroscopy on Methane using Mode-Locked Cr:ZnS Laser

〇(D)WENQING SONG¹, DAIKI OKAZAKI¹, IKKI MORICHIKA¹, SATOSHI ASHIHARA¹ (1.IIS, The Univ. of Tokyo)

Keywords:infrared spectroscopy, Cr:ZnS laser

Background-free (BF) methods have a great potential for ultrasensitive detection because the signal scales with the irradiance of the light source. In this study, we utilize our recently developed mode-locked Cr:ZnS laser to demonstrate BF spectroscopy based on coherent suppression of the background light with a Michelson interferometer for the v₃ +v₄ band of methane around 2.3μm. The spectrum of the BF signal we obtained shows the intensity proportional to the absorbance locating in the corresponding wavelength. Our analysis shows that the SNR of the BF method is enhanced compared to the traditional absorption spectroscopy.