High-power aluminum-free diode lasers provide stable operation at 730 nm
In results presented at the IEEE Lasers and Electro-Optics Society 1998 Annual Meeting (Orlando, FL), researchers from the University of Wisconsin (Madison, WI) described fabrication of aluminum-free diode lasers emitting up to 3.2 W of continuous-wave (CW) light at a wavelength of 730 nm. The indium gallium arsenide phosphide (InGaAsP) active-region devices, with coated front facets, have apertures of 100 µm and produce a single transverse mode. At a reduced output power of 0.5 W, the lasers are stable for more than 700 h. They are grown on substrates misoriented from the <100> direction by 10 toward the <111> direction--a procedure that increases disordering of the confining and cladding layers. This reduces the threshold current density to 450 A/cm2, as well as increasing the characteristic temperature coefficients to a record-high T0 = 115 K and T1 = 285 K, thus rendering the devices less sensitive to temperature. Maximum optical power is limited by filamentation damage induced by small flaws within the material. By improving growth uniformity to reduce filamentation, output power approaching 8 W is possible. Contact: Abdulrahman Ali Al-Muhanna at [email protected].