Current Channeling – End View, Vertical Section, Not to scale p-Type Electrode p-GaAs Cap Layer n-GaAs Current Blocking Layer p-AlGaAs Cladding Layer AlGaAs Active Layer Laser Mode Volume n-AlGaAs Cladding Layer p-GaAs Current Blocking Layer n-GaAs Buffer Layer Path of Current Flow Substrate Z Y n-Type Electrode

Gain Increase and Longitudinal Mode Stabilization of Semiconductor Lasers by means of Current Channeling n-GaAs Current Blocking Layer Channeled Current P-GaAs Cap Layer p-AlGaAs Cladding Layer p-Type Electrode Maximum Overlap of Current and Antinode of Standing Wave X-Y Section Laser Emission Standing Wave AlGaAs Active Layer n-GaAs Buffer Layer Z X Y n-GaAs Substrate (Y-direction normal to screen) n-Type Electrode n-Type Electrode Y-Z Section p-GaAs Current Blocking Layer n-AlGaAs Cladding Layer

Schematic of Current Channeling – Top View (not to scale) X-Y Section n-GaAs Current Blocking Layer ~50nm ~0.25mm Y X Current Path Spacing < ~l/4 n-GaAs Current Blocking Layer Spacing = ~l/2 Current Path is Between Blocking Layers Laser Mode Volume

Schematic of Current Channeling – Y-Z Section Approximately to Scale ~0.5mm Entire Active Region is ~100nm ~0.5mm Z Y Substrate Note: Because of the extreme thinness of the active region, it is not possible to show the entire device to scale

Schematic of Current Channeling in Phased Array Diode Laser– Top View (not to scale) X-Y Section ~0.5mm ~0.25mm Y X Emitter “stripe” End View n-GaAs Current Blocking Layers Spacing = ~l/2; Current Path Spacing < ~l/4 Z Y