Measurements in Passive Resonators

Abstract

The ability of any optical element to operate in a laser cavity is defined by a positive balance of active and passive losses for the cavity with that element. Reflective objects create transmission, scattering, and absorption losses; transmission ones create reflection, scattering, and absorption losses, etc. It is critical for the loss under study to be measured at a specific spatial, spectral, and temporal condition of light emission providing adequate measurement arrangements. Let us consider two methods for passive intracavity measurements of a high specular reflectance: ρr → 1, of a mirror. Such a reflectance may be measured directly or by sensing the difference from unity of the sum of its scattering loss, absorptance, and transmittance, considering a mirror substrate as a vital part.