Broadband optical phase detection and phase noise removal with an optical resonator






A phase noise detection apparatus comprises a laser beam, an optical resonator coupled thereto at a coupling point and a photodetector receiving light from the laser beam. The laser beam and the resonator coupled thereto convert phase noise of light transported by the laser beam prior to the coupling point into intensity noise of light transported by the laser beam thereafter. Intensity noise is converted into an electrical signal by the photodetector. The electrical signal is sent through a first signal path and a second signal path such that the first signal path transports a signal substantially proportional to the intensity noise, which is integrated in an integrator in the second path. Relative gain of the two signal paths can be adjusted and the overall gain of the signal path is preferably such that the optical phase modulator at least partially cancels said phase noise in the optical domain.