An external cavity with a waveguide-grating mirror (WGM) is proposed for a
wide-aperture semiconductor laser. The emission spectra of a laser diode in
the cavity were studied for a collinear and noncollinear incidence of radi
ation on the WGM. The substantial (down to 0.1 nm) narrowing of the emissio
n spectrum was obtained, and a continuos tuning of laser radiation in the r
ange from 10 to 18 nm was demonstrated.