Patent ID: 8953649
Filing Date: 2015-02-10
Classification: H01S

Abstract:
1. A method for quasi-synchronous tuning of a grating external-cavity semiconductor laser to achieve frequency selections, wherein the semiconductor laser comprises a semiconductor laser diode, a grating, and a mirror, one of the grating or the mirror being a rotating member, the method comprising: determining a synchronous tuning point, the synchronous tuning point having a position such that when the rotating member rotates about the synchronous tuning point, a round trip phase difference, within a resonance cavity of the semiconductor layer, of a laser beam emitted by the semiconductor laser diode does not change; locating a quasi-synchronous tuning point in a position with respect to the synchronous tuning point such that an angle of a line connecting the quasi-synchronous tuning point and the synchronous tuning point with respect to a direction of the laser beam, incident on the grating, equals one of (a) Δθwhen the rotating member comprises the mirror, or (b) Δθ/2 when the rotating member comprises the grating, Δθbeing an angle difference between an incidence angle of the laser beam on the grating and a diffraction angle of the laser beam on the grating; and rotating the rotating member around the quasi-synchronous tuning point, wherein a distance between a plane on which a surface of the rotating member lies and the quasi-synchronous tuning point does not change during the rotation.