Single-frequency 1310-nm grating-outcoupled surface-emitting (GSE) semiconductor lasers with output slope efficiencies exceeding 0.1 mW/mA into multimode fibers, threshold currents below 22 mA, and >30-dB sidemode suppression ratios are reported. These GSE lasers consist of 500-/spl mu/m-long active ridges that excite one end of surface-emitting second-order outcoupling gratings with 200-/spl mu/m-long first-order distributed Bragg reflector gratings terminating the laser cavities at both ends. The grating outcouplers range from 10 to 50 /spl mu/m in length. These lasers have an open eye pattern for nonreturn-to-zero signals at 2.5 Gb/s into single-mode fibers. The full-width half-maximum far-field beam divergences range from 1.5/spl deg/ /spl times/ 8/spl deg/ to 5/spl deg/ /spl times/ 8/spl deg/.
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