Abstract: A TO type laser device that can perform long-distance transmission due to a reduced line breadth of laser light. A semiconductor laser device which comprises a laser diode chip (100) that emits laser light; a wavelength-selective filter; a collimating lens (200) disposed in a light path between the laser diode chip (100) and the wavelength-selective filter and to collimate light emitted from the laser diode chip (100); a 45°-partial reflective mirror (300) disposed in a light path between the laser diode chip (100) and the wavelength-selective filter for changing laser light traveling parallel to the bottom of a package into laser light traveling perpendicularly to the bottom of the package; and an optical wavelength supervisory photodiode (500) disposed in a light path along which laser light reflecting from the wavelength-selective filter, after being emitted from the laser diode chip (100), passes through the 45°-partial reflective mirror (300).

Abstract: The present invention relates w a wavelength-convertible semiconductor laser which is driven by a pulse, and more specifically, to a wavelength-convertible semiconductor laser, wherein: an expanded resonator is formed by including a laser diode chip on the outside of a pump semiconductor laser diode chip; and an oscillating wavelength of a pump laser is driven by a pulse determined from the outside of the semiconductor laser diode chip by inserting a filter, which is capable of selecting a wavelength, on the inside of said expanded resonator.