WAVELENGTH-VARIABLE LASER SOURCE

PROBLEM TO BE SOLVED: To provide a wavelength variable laser source where the starting of an optical output and the switching of a wavelength are accelerated, and an interference to the other channel is prevented. SOLUTION: The wavelength variable laser source carries out the negative feedback control of an LD current source 18 based on the detected signal of a wavelength monitor 14 when the wavelength is variable. The wavelength variable laser source is provided with a wavelength switching controller 20 which controls an LD power source control circuit 19 etc. to inject a current to a distributed feedback semiconductor layer 11 to be oscillated (current control initial phase) in the case of starting the optical output or switching the wavelength, and to start negative feedback control from the wavelength monitor 14 (negative feedback control phase) after a temperature is stabilized. COPYRIGHT: (C)2005,JPO&NCIPI