Design and Characterization of a 12-Channel, Dual Wavelength, Fiber-Coupled Laser System

摘要

A compact, ruggedized 12-channel, dual wavelength, fiber-coupled laser system was designed, assembled and tested to support fiber injection experiments. A flashlamp pumped, Q-switched, Nd:Cr:GSGG laser, operating at 1061 nm was assembled and characterized. To optimize the laser for fiber injection, a stable, multimode, Polarization Output Coupled (POC) resonator design was utilized. The design did not use any active cooling and was ideal for low duty cycle applications requiring no more than one shot every 30 seconds. The laser output was frequency doubled to 530 nm utilizing a Type II interaction in a KTP crystal. A nonlinear conversion efficiency of 56 percent was obtained. Two beam splitting and fiber injection modules, one for each wavelength, were utilized to transform the single laser input beam into six parallel fiber channels. Four of the channels were provided for high output energy and two for low energy monitoring. In addition to the 12 fiber optical outputs, full aperture 1061 nm and 530 nm output ports were provided with independent energy adjustments. The entire laser system was packaged into a rugged O-ring sealed aluminum housing to maintain cleanliness. The housing measured 18" X 22" X 2.75" and weighed 43.5 pounds. The capability to externally select wavelength, beam format (fiber coupled or full aperture) and output energy was provided. This was to preserve internal cleanliness and facilitate system operation in dirty environments. Alignment strategies and performance results including laser efficiency, far field beam divergence, nonlinear conversion efficiency, fiber-to-fiber energy uniformity, and fiber output intensity profiles will be presented.