Patent ID: 6493131
Filing Date: 2002-12-10
Classification: H01S,H04B

Abstract:
A device for wavelength locking a wavelength-variable optical signal to a target wavelength which is offset from a wavelength of an optical reference signal by a preselected frequency offset, the device comprising:a photomixer section including a square law detector for mixing the wavelength-variable optical signal with the optical reference signal to produce a beat component and further for producing a frequency test signal from the beat component, wherein the frequency test signal is located at a target frequency when the wavelength-variable optical signal is at the target wavelength; a frequency filter coupled to the photomixer section having a transfer function which varies monotonically over an operating region around the target frequency, for applying a frequency-dependent gain to the frequency test signal to produce an amplitude test signal, wherein the frequency filter applies a target gain when the frequency test signal is located at the target frequency; and comparison circuitry coupled to the frequency filter and adapted to receive an electrical reference signal for comparing the amplitude test signal with the electrical reference signal to determine whether the frequency filter applied the target gain.