Patent ID: 7653097

Claim:
A method of operating a laser source wherein: the laser source comprises: a laser configured to generate an optical signal; and a polarization split and delay unit coupled to the optical signal configured to: split the optical signal into a first and second orthogonally polarized component; create an optical path length difference ΔL between the first and second orthogonally polarized components; and combine the first and second orthogonally polarized components into a combined signal; and the method comprises: modulating the optical signal by applying a wavelength modulation signal to the laser such that the modulated optical signal comprises at least a first wavelength λ 1 and a second wavelength λ 2 , wherein the first wavelength λ 1 and the second wavelength λ 2 are separated by a wavelength difference Δλ; and wherein the wavelength difference Δλ and the optical path length difference ΔL are such that the first component and the second component oscillate back and forth from an in-phase state, where the first and second components are approximately in phase, to an out of phase state, where the first and second components are approximately out of phase.