Abstract: A method and device for measuring the wavelength of a source, for example monitoring a laser used in DWDM fiber optic communications systems, wherein the method and device comprise using a coarse arrayed waveguide grating (AWG) to resolve an ambiguity of wavelength measurement in a fine arrayed waveguide grating. The wavelength monitor or meter of the present invention may be configured as a standalone device suitable for use in many different applications and may also be integrated into a laser or laser array for use in DWDM fiber optic communications systems.

Abstract: A wavelength locked semiconductor laser module has at least one of semiconductor laser of the laser arrays and a heater and/or cooler configured to vary a temperature of the semiconductor laser(s). A phase shifted wavelength locker is configured with wavelength locker temperature sensor and microprocessor to control of the wavelength of the semiconductor laser of the laser arrays instantaneously with absolute precision.