High-quality extended cavity ridge lasers fabricated by impurity-free vacancy diffusion with a novel masking technique

By using phosphorous doped (5% wt P) silica as masking material and standard silica capping to promote quantum well interdiffusion, GaAs-AlGaAs ridge waveguide QW lasers with integrated transparent waveguides were fabricated. With a selective differential blue-shift of 30 nm in the absorption edge, devices with 400-μm/2.73-mm-long active/passive sections exhibited threshold currents of 8 mA in CW operation, only 1 mA higher than that for normal lasers of the same active length and from the same chip. This 14% increase in threshold current was accompanied by a slope efficiency decrease of 40%. Losses of 3.2 cm/sup -1/ were measured in the passive waveguides at the lasing wavelength using the Fabry-Perot resonance method. This value is among the lowest reported so far using an impurity-free disordering technique.