Enhancing sensitivity beyond the optical effective pathlength in cavity-enhanced spectroscopy

Cavities utilizing high-finesse optical resonators provide effective pathlength of several kilometers for light-matter interaction[1]. However as compared to near-IR wavelength region, in the mid-IR region absorption measurements lack high sensitivity due to the combination of highly reflective mirrors and lower detectivity of detectors [2]. To enhance sensitivity beyond the optical effective path length, Off-Axis Cavities with three spherical mirrors are modelled.