Claddings for YAG single crystal high power fiber lasers

Abstract

Doped single-crystal YAG fibers used as single-mode lasers require claddings with precise refractive index and high thermal conductivity. Three cladding materials that use coextrusion of green cladding on fiber cores as an initial processing step are described: 1. Undoped YAG cladding, followed by sintering or hot isostatic pressing. 2. Ca 3 Ga 2 Ge 3 O 12 garnet cladding that melts beneath 1400°C. 3. LiCa 2 Mg 2 As 3x V 3-3x O 12 garnet cladding that melts beneath 1100°C. Microstructures are characterized by TEM. Equipment and procedures are described. Garnet refractive index models are developed and validated to predict cladding refractive index. Advantages and disadvantages of the different claddings are compared.