[11a-W935-1~10] 3.8 Optical measurement, instrumentation, and sensor

▼ [11a-W935-5] Amplifier Assisted CRDS (Cavity Ring-down Spectroscopy) toward Compact Breath Sensing

〇(D)Wenying Li¹, Yu Han¹, Zanhui Chen¹, Haisong Jiang¹, Kiichi Hamamoto¹ (1.Kyushu Univ.)

Keywords:gas sensing, waveguide, CRDS

Breath sensing using cavity ring-down spectroscopy (CRDS) method is attractive due to its real time sensing in addition to the capability of high sensitivity. Using waveguide for sensing realizes several meters’ optical path integration that needs for measuring ppm-order components in human breath into a compact area. To realize ppm-order gas detection, amplifier assisted CRDS system is proposed to compensate the propagation loss of the waveguide. The amplifier in CRDS system, however, may result in self-lasing at specific wavelength in case of high pumping condition. Once self-lasing happens, signal light loose the gain from amplifier. In this work, we propose the scheme of polarization direction control so as to prevent the self-lasing. As a result, the gain improvement of 24 dB has been successfully confirmed.