Micromachined Fused Silica Pump Combiners with Signal Feed Throughput

ABSTRACT: We propose to fabricate a high performance signal and pump combiner for high-power fiber lasers and fiber amplifiers. We will use advanced glass micromachining processes that will alleviate the fabrication challenges associated with either tapered fused fiber couplers or side-pumped fused coupler. A central robust fused silica structure will be micromachined. The pumps and signal fiber will be inserted in precision-machined pockets found in that structure. This will provide for a very accurate way of positioning the various fibers relative to each other. The fibers will be permanently bonded in place using a high optical quality glass-brazing process. These fabrication processes are very reproducible and are cost-effective in volume production. Compatibility with different types of fiber will be demonstrated. BENEFIT: The demands placed upon pump and signal combiners in high power fiber amplifiers are severe. The combiner must introduce very little optical loss, should not affect the beam optical characteristics, and operate steadily while subjected to significant temperature transients. We are proposing to address these design challenges by developing a micromachined fused silica combiner that will accurately position the various fibers and will optimize the transfer of power from the pump lasers to the gain fiber. We expect that this high-power signal and pump combiner will gain wide acceptance among fiber laser manufacturer. The proposed combiner can easily be adapted to various types of fibers, including fibers of various diameters, which should increase the commercial opportunity.