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There is demand for improved deep-space satellite communications links with increased data rates to accommodate new sensor technologies and increased sensor payloads on spacecraft. It is imperative that new solutions be compact in size, light in weight, be high speed, and highly power efficient. Optical links offer potential improvements in power, size and weight due to a substantially narrower beam and smaller components. Solutions using fiber-laser transmitter master-oscillator power-amplifiers (MOPA) have been investigated previously, but methods for improving the system power efficiency are needed. In this paper we will present methods for improving the wall-plug efficiency of fiber MOPAs for deep-space communications. A high-power, wavelength-stabilized, 1550 nm seed laser with an external modulator is used to reduce the number of amplifier stages. In addition, resonant pumping in the 1430 to 1530 nm band improves pump absorption and, hence, wall-plug efficiency. A first-stage amplifier is used in order to maximize extraction efficiency at high gain. The design targets a wall plug efficiency of 20% with more than 1 kW of peak power per pulse and over 10 W of average power. An amplifier operating at 1532 nm also has the advantage of commercial off-the-shelf components with demonstrated reliability. |
