Semiconductor laser with tapered-rib adiabatic-following fiber coupler for expanded output-mode diameter

Abstract
A new expanded-mode AlGaAs diode laser with reduced far-field divergence and 0.9 dB single-mode optical fiber coupling loss is demonstrated. This new laser achieves a two-dimensional (2-D) expansion of the fundamental output mode with a rib waveguide tapered in only one dimension. Stable fundamental-mode operation with a narrow, 5.7/spl deg/ by 7.40 full-width-at-half-maximum far-field divergence is observed well above lasing threshold. Tapered waveguide dimensions are compatible with conventional optical lithographic techniques, making this device suitable for mass production.