Patent ID: 8184362

Claim:
A method of phase locking a multi-stage parallel fiber amplifier, comprising: receiving a signal beam of a first wavelength from a first stage of an amplifier path onto a fiber; pumping said fiber using a second wavelength to produce a saturated signal beam having a phase and amplitude that do not substantially change based on an amplitude of said signal beam; outputting said saturated signal beam to a second stage of said amplifier path to produce an amplified beam; detecting at least a portion of said amplified beam from said second stage to produce a phase indication of said amplified beam relative to a plurality of phases of a plurality of amplified beams of a plurality of amplifier paths; modulating a pump level of said first stage based at least in part upon said phase indication to control a phase of said amplified beam; and controlling said plurality of phases of said plurality of amplified beams of said plurality of amplifier paths to phase lock the multi-stage parallel fiber amplifier.