High efficiency pulsed lasers have been considered to be an enabling technology to build high power transmitters for future deep space high rate space communications. However, to achieve a high peak power at a high repetition rate and with a short pulse width and >25% wall plug efficiency still remains an issue unsolved. PolarOnyx proposes a novel approach targeting to make 20W high power fiber laser at 1550 nm and resolve the issues of efficiency. A tabletop feasibility demonstration has been carried out at the end of Phase I. A prototype will be delivered at the end of Phase II.