Abstract Ridge-type 0.808£gm AlGaAs diode lasers with a planar waveguide structure have been successfully fabricated. After ridge etching, a SiO2 thin film is sputtered onto the sample as the surface passivation layer, and then the BCB¡]Benzocyclobutene¡^polymer is coated for surface planarization. Before matalization, the thin polymer and SiO2 layers above the ridge are removed by dry etching technique. The fabrication was completed by evaporating contact metals to the samples. The cavity length of the measured laser diode is 900£gm. The threshold current density and threshold voltage of the planarized device are 385 A/cm2 and 2.1 V. The differential quantum efficiency as large as 82% is obtained. In addition, a conventional ridge-type laser is also fabricated for comparison. The threshold current density and threshold voltage of the conventional ridge-type device is 385 A/cm2 and 2.5 V. The differential quantum efficiency of is 77%.