High peak power short 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 over 100 MHz and with a short pulse width and >25% wall plug efficiency still remains an issue unsolved. PolarOnyx proposes a novel approach targeting to make 10 MHz to over 100 MHz high repetition rate high power fiber laser at 1550 nm and resolve the issues of modulation induced chirp, pulse distortion and nonlinear effects by using COTS components and employing our proprietary technologies in specialty fibers, spectral shaping and pulse shaping techniques. Space qualification will also be addressed in laying out the pathway towards space deployment. A tabletop demonstration will be carried out at the end of Phase 1. A prototype will be delivered at the end of Phase II.