Optical coherent combining of high-power optical amplifiers for free-space optical communications

Highly efficient coherent beam combining (CBC) of two very-high-power optical amplifiers (VHPOA) with applications to long-range FSO communications such as ground-to-space feeder links is presented. The CBC setup is designed to minimize the telecom signal degradation, with a polarization beam splitter used to minimize the power fluctuations and to control the output polarization state of the beam. The system delivers 80 W output power and is proven to be compatible with 25 Gb/s telecom signals with a less than 1 dB power penalty.