FWM-PEV statistics measurements in 8 channel 50W high power WDM PPM Tx with and without TDM-based FWM mitigation

Abstract

Fibertek is developing a power efficient, space qualifiable Eight WDM Channel PPM Downlink Seed LAser Module (SAM) with TDM based FWM Mitigation Capability. SAM will be compatible with the space qualifiable, high TRL, 8 WDM channel, 50W WDM Amplifier prototype that was delivered in early 2021. Together the two modules make up a complete High TRL spaceflight high power DSOC WDM Transmitter. Measurements of FWM-PEV statistics using realistic PPM patterns are presented. Measurements show that FWM mitigation is not needed for PPM orders 16 and 32. TDM based FWM mitigation algorithm using 2 wavelength subslots is implemented on the realistic PPM patterns for 5 out of the 6 PPM64 and PPM128 formats successfully. Mitigation in all cases results in significant improvement in PEV statistics. Achieved statistics for all PPM formats are considered manageable using FEC.