Spectral properties of angled-grating high-power semiconductor lasers

The beam quality in high-power semiconductor lasers are generally limited by filamentation and weak lateral mode control. The use of grating has recently been explored in a variety of ways. The /spl alpha/-DFB laser in particular has been demonstrated to have diffraction limited beam qualities and high power levels. The optical cavity of the /spl alpha/-DFB laser is shaped like a parallelogram several hundred microns wide by a few millimeters long. A wide stripe of grating is etched along the length of the cavity and oriented at an angle to the facets.