Patent ID: 6967983

Claim:
A tunable distributed Bragg reflection type semiconductor laser apparatus comprising an active waveguide having a function of light amplification and a waveguide reflector that has a diffraction grating and adjusts an emission wavelength by varying reflection wavelength range are connected monolithically in a traveling direction of light, wherein the length of said active waveguide L a , the phase of said diffraction grating φ G , the operating temperature of the laser T LD , and the tunable wavelength range Δλ are specified so that a phase of a reflected mode φ with respect to an incident mode that oscillates at a single wavelength and enters the waveguide reflector takes a value in the range greater than 0 to π, and φ=2πN−((4n.sub.a(T.sub.LD))/λ)−2φ.sub.G, wherein n.sub.a is a refractive index of an active region and N is an integer.