Patent ID: 8520709
Filing Date: 2013-08-27
Classification: H01S

Abstract:
1. A method of operating a laser configured to emit an output signal at at least one central channel optical frequency and comprising an external cavity including a gain medium, a spectrally selective optical filter and a first optical phase element whose phase is controllable through a first control parameter, the method comprising the steps of: applying an electrical modulation signal to the first control parameter so as to create a modulation of a length of a cavity optical path with a modulation depth that causes an optical frequency excursion and an amplitude modulation of the output optical signal, wherein the first optical phase element exhibits a variation of optical transmissivity at least within a variation of the first control parameter induced by the modulation signal and wherein the spectrally selective filter has an optical transmissivity variable in correspondence of at least said optical frequency excursion induced by the electrical modulation signal; detecting an amplitude of the modulation of the output optical signal, and adjusting the length of the optical path of the cavity in order to select the transmissivity of the spectrally selective filter in such a way that its first derivative with respect to the frequency within the optical frequency excursion has opposite sign compared to a first derivative of the transmissivity of the first phase element within an interval of variation of said first control parameter, so as to reduce the modulation amplitude of the laser output signal.