A light generating apparatus includes: a submount; a semiconductor laser chip mounted on the submount; a substrate which is mounted on the submount and includes an optical waveguide; and a substance having a predetermined thickness which is disposed between the semiconductor laser chip and the substrate. In an oscillation wavelength stabilizing apparatus for a light source, the light source is a semiconductor laser which includes: an active region for providing gain; and a distributed Bragg reflection (DBR) region for controlling an oscillation wavelength. The apparatus includes 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.sub.o corresponding to a predetermined wavelength value, and then monotonously varies the DBR current in a second direction which is opposite the first direction beyond the detected value I.sub.o, and then monotonously varies the DBR current in the first direction again to set the DBR current at the detected value I.sub.o, thereby fixing the oscillation wavelength of the semiconductor laser chip at the predetermined wavelength value.