Wavelength tunable laser of small size

摘要

A wavelength tunable laser device includes: a pair of reflection mirrors (32); a semiconductor element (30) disposed between the pair of reflection mirrors (32), the semiconductor element (30) integrating a region (G) for providing an optical gain, a region having a wavelength tunable filter function and a phase control region (PH); and an optical filter disposed between the semiconductor element and one of the pair of reflection mirrors, the optical filter having periodical transmission wavelengths. A wavelength tunable laser device is provided which is easy to be controlled and can be made compact.