660 nm angled grating DFB lasers

We demonstrate the first visible wavelength angled DFBs with pulsed power levels approaching 0.5 W and CW powers of 200 mW. The device structure is fabricated in the same way as visible wavelength broad area DFB lasers, except that both the gain region and the grating are tilted with respect to the facets. The optical mode is confined laterally by the diffraction grating, and only the component normal to the facet is reflected back into the cavity. Since the grating is operated at an angle, the pitch is considerably increased, and a first order grating is possible even at short wavelengths. The grating reflectivity is highly angle and wavelength selective, and filters out higher order spatial modes with different propagation constants, resulting in single mode operation. The device was fabricated using MOCVD with a two step growth on a GaAs substrate. The first epitaxy included a lower n-type InAlP cladding region, an undoped InAlGaP waveguide containing InGaP quantum wells, and a p-doped InAlGaP grating layer. These devices provide nearly collimated beams in the lateral direction are not limited by catastrophic mirror damage