A vertical external cavity surface emitting laser (VECSEL) in which the
full-width at half maximum (FWHM) of laser light is reduced by two etalon
filter layers to improve the efficiency of second harmonic (SHG) crystal
is provided. The VECSEL includes: a laser chip for generating laser
light; a first etalon filter layer formed on the laser chip; a second
etalon filter layer that is formed on the first etalon filter layer and
has a different refractive index than the first etalon filter layer; a
first mirror separated from and disposed obliquely to the laser chip; a
second mirror for reflecting the laser light reflected from the first
mirror back to the first mirror to form a cavity with the laser chip; and
an SHG crystal disposed along an optical path between the first and
second mirrors and doubles the frequency of the laser light generated in
the laser chip.