Fiber Amplifier Array For Transmitter Power Scaling And Atmospheric Aberration Mitigation

摘要

We describe our concept for a power scalable, coherently combined fiber amplifiers with built in high-speed ( > 1 kHz) phase correction capability. We use the diode pump current to adjust the optical lengths of the fiber amplifiers. This provides a simple and robust method that always keeps the beam in the fiber until the output end and does not require any additional devices to be introduced in the beam path or tight optomechanical adjustments. We have demonstrated this concept in the laboratory as well as in a 400m atmospheric range in a laser communication link using seven 1 W Er:Yb fiber amplifiers. Such a link can achieve communications bandwidths comparable to fiber links ( > 100GHz) by relaunching the beam that has traversed the atmosphere back into a single-mode fiber as we have demonstrated. We report the near and far field of the transmitter beam shapes and automatic small angle steering capability for the transmitter beam to follow the slight motions of the receiver. Our approach can be scaled to much higher output power ( > 10kW) by employing higher power fiber amplifiers and larger number of amplifiers. The power and the number of the amplifiers we used in our demonstration were limited by available funds.