Optical amplifier assisted cavity ring down spectroscopy (CRDS) method for compact infrared sensing

Waveguide based CRDS is attractive for its possibility of realizing compact breath sensing system. The waveguide propagation loss, however, loses the light power that leads to the degradation of the sensitivity. We propose optical amplifier assisted CRDS method to detect 0.5% CH₄ for the case of utilizing such loss waveguide.