Patent ID: 7733933

Claim:
A wavelength tunable laser apparatus comprising: a semiconductor substrate including: a region which emits light when a current is applied thereto and having a first semiconductor composition, and a phase control region including a pn junction section having a second semiconductor composition; a gain chip in which the light-emitting region and the phase control region are connected to each other with a waveguide; a wavelength selective mirror constituting a cavity between itself and an optical output end surface of the gain chip; a current source for causing a positive current to flow into the pn junction section in the phase control region; a voltage source for applying a negative bias to the pn junction section in the phase control region; and a control unit for selectively driving any one of the current source and the voltage source depending on a direction of wavelength shift; wherein the first semiconductor composition of the light-emitting region and the second semiconductor composition of the phase control region are different from each other.