Patent ID: 6816517
Filing Date: 2004-11-09
Classification: H01S

Abstract:
An arrangement for tuning the wavelength of a laser having a micro-electro-mechanical (MEM) device to a desired wavelength comprising:a laser defining a laser cavity; a movably positionable MEM device having a mirror surface positioned relative to the laser cavity to reflect laser light generated by the laser, wherein the MEM device is movably positioned to tune the wavelength of the laser cavity; a wavelength selective device implementing a peaked passband function including a center wavelength which is the desired wavelength, in a system employing the laser; a dither generator for generating a sinusoidal dither signal at a dither frequency which is applied to the MEM device, wherein the position of the MEM device oscillates at the dither frequency which produces a periodic change in the length of the laser cavity and a corresponding change in the laser output wavelength which passes through the wavelength selective device; a dither wavelength locked feedback loop for dynamically adjusting the position of the MEM device to maintain the laser output wavelength nominally centered at the desired wavelength; a detector detects the laser output after the dithered laser output has passed through the wavelength selective device and produces a detector output signal; a mixer wherein the detector output signal is mixed with the dither signal to produce an output cross product feedback signal which provides an indication of whether the laser wavelength is aligned with the center wavelength of the wavelength selective device, and if not provides an indication of what direction and by what amount the wavelength of the laser must be shifted to be brought into alignment with the center wavelength of the wavelength selective device.