Coherent Detection Eye-Safe LIDAR Systems Based on Large Mode Area Fiber Amplifiers

ABSTRACT: nLIGHT proposes the development of of an all-fiber, master oscillator power amplifier (MOPA) configuration that will meet the Air Force requirements for a 10 mJ, 300 ns pulsed laser source. With the exception of the output power amplifier fiber, this device will be based on commercial off the shelf (COTS) components. This proposal is based on an Er-doped fiber amplifier that is resonantly-pumped by highly efficient 153x nm fiber-coupled pump lasers. By utilizing novel fiber laser amplifier technologies already demonstrated and reported, nLIGHT anticipates that we will achieve>70% optical to optical efficiency for Er-doped amplifier. The use of high efficiency 153x nm diode lasers in conjunction with highly efficient fiber coupling techniques indicates that we will be able to achieve>40% electrical to optical power conversion of the pump laser modules. Resonant pumping of the fiber amplifier leads to a quantum defect of ~ 4.5%, simplifying thermal management of the fiber amplifier, and leading to overall electrical to optical efficiency in the range of 25%. BENEFIT: Commercial applications of this type of laser system may be used in materials processing where the eye-safe wavelength and high peak power capability of the fibers developed may provide an advantage in terms of application speed or quality. If such systems are found to be useful for industrial applications, nLIGHT will pursue commercialization of such products as an addition to their existing line of 1µm commercial PFL products. For instance, there is substantial interest in 15xx to 19xx nm lasers for a variety of plastics welding and biomedical applications. It is expected that these high average power, high pulse energy eye-safe fiber lasers will be useful in materials processing, biomedical, and other light industrial applications.