Patent ID: 7133428

Claim:
An oscillation wavelength stabilizing apparatus for a light source, wherein the light source is a semiconductor laser comprising: an active region for providing gain; and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength, the apparatus comprising a control section which monotonously varies, in a first direction, a DBR current to be input to the DBR region while detecting the oscillation wavelength of an output light of the semiconductor laser so as to detect a DBR current value I 0 corresponding to a predetermined oscillation wavelength value, and then monotonously varies the DBR current in a second direction which is opposite the first direction beyond the detected value I 0 , and then monotonously varies the DBR current in the first direction again to set the DBR current at the detected value I 0 , thereby fixing the oscillation wavelength of the semiconductor laser at the predetermined oscillation wavelength value, wherein the detected value I 0 of the DBR current is set so as to satisfy equation I 0 =(I 1 +I 2 )/2 where I 1 is a first DBR current value at which mode-hopping occurs and I 2 is a nearest DBR current value greater than at which mode-hopping occurs.