SEMICONDUCTOR-LASER WITH TAPERED-RIB ADIABATIC-FOLLOWING FIBER COUPLER FOR EXPANDED OUTPUT-MODE DIAMETER

A new expanded-mode diode laser with reduced farfield divergence and 0 .9 dB single-mode optical fiber coupling loss is demonstrated, This ne w 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 degrees by 7.4 degrees full-width-at-half-maximum far-field divergence is observed well above lasing threshold, Tapered waveguide dimensions are compatible with co nventional optical lithographic techniques, making this device suitabl e for mass production.