Vertically stacked multiple-quantum-wire semiconductor diode lasers

We report the structure and lasing characteristics of GaAs/AlGaAs vertically stacked multiple-quantum-wire (QWR) semiconductor lasers grown by organometallic chemical vapor deposition on V-grooved substrates. The active region in these lasers consists of three crescent-shaped wires, placed at the center of a single-mode optical waveguide. The higher optical confinement factor, compared to single-QWR structures, leads to reduced threshold currents, as low as 0.6 mA for high-reflection coated devices at room temperature. The lower threshold carrier density results in oscillation at a lower QWR subband as compared to single-QWR laser structures.