HIGH-QUALITY EXTENDED-CAVITY RIDGE LASERS FABRICATED BY IMPURITY-FREEVACANCY DIFFUSION WITH A NOVEL MASKING TECHNIQUE

By using phosphorous doped (5% wt P) silica as masking material and st andard silica capping to promote quantum well interdiffusion, GaAs-AlG aAs ridge lasers with integrated transparent waveguides were fabricate d. With a selective differential blue-shift of 30 nm in the absorption edge, devices with 400-mu m/2.73-mm-long active/passive sections exhi bited threshold currents of 8 mA in CW operation, only 1 mA higher tha n that for normal lasers of the same active length and from the same c hip. This 14% increase in threshold current was accompanied by a slope efficiency decrease of 40%. Losses of 3.2 cm(-1) were measured in the passive waveguides at the lasing wavelength using the Fabry-Perot res onance method. This value is among the lowest reported so far using an impurity-free disordering technique.