A Distributed Bonding Interfacial Loss Characterizing Method of Composite Crystal Based on Optical Low-Coherence Domain Reflectometry

Composite crystals are the key component of high-power solid-state lasers. The bonding interfacial loss of composite crystal slabs is a critical parameter to evaluate the quality of the bonding interface. A distributed method based on optical low-coherence domain reflectometry is proposed to measure the bonding interfacial loss. Distance-related reflecting coupling loss (RCL) and tilt were analyzed and calibrated to ensure accuracy. The interfacial loss of a Yb:yttrium aluminum garnet (YAG)/YAG crystal was measured and demonstrated as an example. This distributed method solves the problem that the weak reflection of the bonding interface cannot be eliminated in the traditional transmitted insertion loss test.