Patent ID: 7130322
Filing Date: 2006-10-31
Classification: H01S

Abstract:
1. A wavelength tunable laser comprising: a semiconductor optical amplifier for emitting a laser beam; a wavelength tunable filter arranged in an optical path of the laser beam; a first optical filter arranged in the optical path of the laser beam and provided with a periodical transmissive wavelength; two reflective members arranged so as to sandwich said semiconductor optical amplifier, said wavelength tunable filter, and said first optical filter, therebetween, said two reflective members being for resonating said laser beam; a phase shifter for controlling a phase of the laser beam resonating between said reflective members; a first unit to split light and a second unit to split light for splitting part of the laser beam passing through one of said reflective members; a first optical detector for detecting an intensity of the laser beam split by said first unit to split light; a second optical filter arranged in the optical path of the laser beam split by said second unit to split light and provided with a periodical transmissive wavelength; and a second optical detector for detecting the intensity of the laser beam passing through said second optical filter, wherein said phase shifter controls phase of the laser beam so that a ratio of the intensity detected by said second optical detector to the intensity detected by said first optical detector comes to a certain value.