1.55 µm DFB lasers incorporating etched lateraltaper spot size converters

The authors describe the fabrication and characterisation of 1.55 µm wavelength DFB lasers with integrated, etched lateral taper, spot size converters. The buried ridge structure lasers were fabricated by conventional two-stage growth and processing techniques. Typical threshold currents of 10–15 mA were achieved with output powers up to 25 mW at 100 mA drive and with high singlemode yield. Coupling efficiencies to singlemode fibre were ~40% with positional tolerances of approximately ±2 µm at the –1 dB power point.