The present invention relates to a
wavelength-
tunable laser, which can tune an oscillating
laser wavelength and can be manufactured in a small size, comprising: a
laser diode chip (100) for emitting a
laser beam; a
partial reflection mirror (500) for optical feedback, which partially reflects the beam emitted from the
laser diode chip (100) so as to enable the reflected beam to be fed back to the
laser diode chip (100); a collimation lens (200) provided on an
optical path between the
laser diode chip (100) and the
partial reflection mirror (500) for optical feedback so as to collimate the beam emitted from the laser
diode chip (100); a
wavelength-tunable
selective filter (300) for converting the wavelength transmitted according to the temperature; a phase compensator (350) of which a
refractive index is changed according to the temperature and which offsets a change in the
refractive index according to the temperature of the
semiconductor laser
diode chip (100) or the wavelength-tunable
selective filter (300); and a 45 degree reflection mirror (400) for switching the direction of the laser beam from the laser beam traveling in the horizontal direction with respect to a bottom surface of a
package, to the laser beam traveling in the vertical direction with respect to the bottom surface of the
package, wherein the laser diode chip (100), the wavelength-tunable
selective filter (300), and the phase compensator (350) are disposed at an upper part of a
thermoelectric element (900) so as to change the wavelength oscillating according to a change in the temperature of the
thermoelectric element (900).