Performance of 100G telecom modems with variable channel outage durations for flexible data rate free-space laser communications

We present a systematic investigation of receiver time dynamics of commercial 100-Gbps coherent transceivers with the intent of using such transceivers with variable data rates less than 100 Gbps for free-space laser communications missions. Applying a post-transmitter but pre-amplifier intensity gating can extend the operating range of such commercial transceivers to beyond the traditional LEO cross-links and thus can enable further proliferation of compact lasercom terminals. Originally designed for slowly-fading telecom fiber channels, telecom coherent receivers are not necessarily compatible with fast switching time dynamics. We report the statistics of the transceiver operation through the time dynamics of an atmospheric channel, as well as the transceiver recovery time for systematic microsecond-to-millisecond class outage durations. Several commercial transceivers are investigated, and operational regimes for low duty cycle waveforms are identified that can support efficient operation at data rates much lower than 100 Gbps.