Simulation of Dicke-narrowed molecular spectra recorded by off-axis high-finesse optical cavities

Simulations of molecular spectral profiles recorded in the Dicke narrowing regime by off-axis high-finesse optical cavities are presented. The influence of experimental parameters on the transmitted lineshapes is investigated on the basis of a model that takes into account the effect of the cavity transfer function. In particular, the collisional narrowing pressure range is found to shrink until disappearance as the molecular absorption increases. It is also shown that fitting the measured lineshapes with a pure Galatry function, i.e. neglecting instrumental effects, may lead to discrepancies of several tens percent in the extracted line parameters.