Fiber amplifiers for coherent space communication

We report on the application of double-clad doped fiber amplifiers for cohe rent space communication systems using a master oscillator power amplifier (MOPA) design at 1.06 mum. The master oscillator is either a single-frequen cy Nd:YAG solid-state laser or a distributed-feedback fiber laser. The powe r amplifier is a diode-laser-pumped double-clad Nd doped fiber with polariz ation control, 20-dB gain, and about 1.3 W output power. A dual stage confi guration using a solid-state Nd:YAG amplifier as second stage is presented as well, increasing the output power to 3.5 W with ts-dB gain,We also repor t on the possibility to integrate a single-frequency fiber laser, an all-fi ber phase modulator, and a fiber amplifier to build an all-fiber phase-modu lated MOPA, Up to 1 W continuous-wave output phase-modulated with a bandwid th of 196 MHz has been achieved.