Compact all-fiber 2 micron isolator and pump combiner

This proposal is for the development of new all-fiber based isolator and side pump combiner for use with high-power fiber lasers operating at 2 micron wavelength. Although the current 2 micron fiber lasers are approaching 1 KW level, the developments of 2 micron fiber-based passive components are far lag behind. NP photonics proposes an all-fiber based Rare-earth doped phosphate glass fiber isolator and a high power side pump combiner that can be used for further power scaling up of 2 micron fiber laser system, which can be used in laser radar, remote sensing, medicine, material processing, direct energy weapon, and infrared (IR) countermeasures. The proposed Faraday rotation fiber offers high Verdet constant, short working distance, low insertion loss, low propagation loss, and all-fiber solution. It also eliminates free space cavity alignment, bulky size, complicated thermal management, and large loss that are common with free space optical isolator. All-fiber optical isolator/Faraday rotation fiber device can be widely used in various laser system, such as single frequency fiber laser, high power/energy fiber laser, fiber amplifier, electric/magnetic field fiber sensors etc. BENEFIT: The successful completion of the proposed compact all-fiber isolator and pump combiner can bring immediate commercial applications. It can be integrated into DOD’s KW level 2 micron fiber laser system used for various military applications such as, infrared missile countermeasures, high resolution, long-range target identification, direction energy weapon, and remote sensing of biological or chemical agents. Their compact size, all-fiber structure, environmental stability, low insertion loss, good heat dissipation, and high power/intensity damage threshold will make it readily be adopted to various commercial markets such as telecommunications, single frequency fiber laser, high power CW laser, high energy pulse fiber laser, and fiber amplifier.