Coherent Beam Combining Element for Five 150-W Fiber Lasers by Volume Bragg Gratings in PTR Glass.

摘要

A compact beam combiner based on multiplexed volume Bragg gratings (VBGs) recorded in photo-thermo-refractive (PTR) glass was demonstrated. This element was designed to provide efficient superposition of 5 coherent beams from 150 W fiber amplifiers operating at the testbed developed at AFRL (KAFB). Five VBGs were multiplexed in a PTR glass wafer in such a way that they have common (degenerate) Bragg angle. Thus it will take the 5 beams which are incident from 5 different angles and superimpose the 5 beams on top of each other in space and the direction that correspond to a common Bragg angle. In contrary, when it is illuminated by a single laser beam from the opposite direction, it split this beam into 5-channels.