Patent ID: 6108362
Filing Date: 2000-08-22
Classification: H01S

Abstract:
A tunable laser source for providing an optical output signal in any one of N different longitudinal modes, comprisinga gain section including an MQW active region, a DFB region optically coupled to said active region for selecting the nominal wavelength of the longitudinal mode which lases, and a first waveguide optically coupled to said active region to permit egress of the laser output signal, characterized in thata composite reflector is optically coupled to one end of said first waveguide so as to form a cavity resonator with said DFB region, said composite reflector including an MQW second region optically coupled to said MQW active region, a second waveguide having one end optically coupled to said first waveguide, and a relatively high reflectivity dielectric layer disposed at the other end of said second waveguide,a first electrode that enables voltage to be applied to said MQW second region to induce therein a quantum confined stark effect, thereby to alter the wavelength of said output signal, and a second electrode that enables drive current to be applied to said active region, andthe current applied to said active region and the shape of said first waveguide are mutually adapted so that said N longitudinal modes have essentially the same threshold gain and so that a portion of said DFB region spanned by said first waveguide is segmented into N zones, each zone providing optical feedback at a different wavelength corresponding to a different one of said longitudinal modes.