Ridge Waveguide Laser Integrated with Spot-Size Converter in a Single Step Epitaxial for High Coupling Efficiency to Single-Mode Fibres

A 1.55-μm laser diode integrated with a spot-size converter was fabricated in a single step epitaxial by using the conventional photolithography and chemical wet etching process. The device was constructed by a conventional ridge waveguide active layer and a larger passive ridge-waveguide layer. The threshold current was 40mA together with high slope efficiency of 0.24W/A. The beam divergence angles in the horizontal and vertical directions were as small as 12.0°× 15.0°, respectively, resulting in about 3.2-dB coupling losses with a cleaved optical fibre.