<p>A GaN based semiconductor laser (1) emits a first laser beam of single polarization having a first wavelength; an optical resonator (30) includes a solid laser medium which is excited by incidence of the laser beam and oscillates a second laser beam having a second wavelength different from the first wavelength; and a polarization switch (6) varies the wavelength of a laser beam to be emitted from the optical resonator (30) or the intensity ratio of a plurality of laser beams to be emitted from the optical resonator (30) by switching the polarization direction of at least one of the first and second laser beams. With such an arrangement, a plurality of laser beams can be utilized effectively.</p>
