Cavity Enhanced Spectroscopy

Abstract

This thesis aims to develop novel alignment-free miniaturized cavity-enhanced spectroscopy techniques on the scale of optical fibers and on the microsystem tech-nologies. To this end, a novel alignment-free active intra-cavity single and dual cou-pler fiber-based cavity-enhanced has been proposed. The former configurations have been studied analytically and numerically. Then, the configurations have been vali-dated experimentally. A simulation model for the enhancement factor in the effective length has been elaborated. The model results have been compared with the experi-mental results. An enhancement factor of 942 has been reached-which is the highest enhancement factor achieved in the fiber-based cavity-enhanced techniques. In addition to, another alignment-free novel technique based on multi-longitudinal mode laser intensity spectroscopy-enabling to couple higher power to the optical cavity-has been proposed. The effect of the gain saturation on the effective length has been studied analytically and numerically. Besides, a novel RF-frequency based cavity-enhanced spectroscopy technique has been proposed. The technique is based on the detection of high frequency spectroscopic signal to eliminate the flicker noise.