Multi-kW Uplink Fiber-Laser Beacon with Agile Signal Format

 Laser beacons with scalable powers are needed for ground to deep-space optical communication uplinks. They serve as absolute reference for tracking of spacecraft during the downlink laser communication. For such space communication link distances the beam spread due to diffraction is significant enough that only few photons are collected by a moderate size optical telescopes on the spacecraft. This necessitates photon-counting detectors suited for the space environment, along with increasing the output power of the laser beacon. Ultra low noise silicon avalanche photo-detector (Si-APD) based position-sensing detectors are used on the spacecraft to detect the laser beacons. Such Si-APDSs are also radiation-hardened and compatible with space-environment operation. It is therefore desirable to operate at shorter wavelengths ~1000nm, where Si-APDs have improved spectral responsivity. This helps to improve the SNR for tracking, and consequently reduce the uplink laser power requirements. Under Phase 2 program Fibertek will design and build a single-channel uplink laser beacon transmitter operating at 1030nm, capable of 500W average output power and 500kHz 16-PPM ary format operation. Inputs from end-user will be solicited for intended use and application, so as to drive the design requirements. Baseline multi-stage 1024nm nm 300W Yb-fiber amplifier architecture demonstrated in Phase 1 will be transitioned to highly robust 'all-fiber' configuration. Proposed design and prototype hardware is based on COTS fiber-optic technology platform, thereby leading to TRL = 4 – 5 level for the SBIR Phase 2 deliverable. More »