Low noise resonant amplification by optical injection locking and residual phase noise cancellation

We demonstrate a resonant optical amplifier that combines injection locking with feed-forward cancellation of residual phase noise. The wavelength-agnostic architecture uses a diode laser as a power amplifier while preserving the spectral purity of a weak reference. The residual phase error is measured via optical heterodyne detection and canceled using feed-forward phase correction. The amplifier achieves up to 38 dB phase noise reduction over injection locking alone at Fourier frequencies above 1 kHz for injection ratios down to -57 dB. This approach enables amplification of low-power, low-noise optical references, including individual lines from optical frequency combs with minimal ASE.