Three-layer waveguide InGaAsP/lnP injection lasers

Injection lasers with a three-layer waveguide emitting at the wavelength of about 1.3 μ were made and investigated. The liquid phase epitaxy method was used to form heterostructures on n- and p-type InP substrates and these heterostructures had lower threshold currents than conventional double-sided heterojunction lasers. A heterostructure with a three-layer waveguide had a thin active region (0.05–0.2 μ) consisting of a quaternary solid solution with adjoining layers of a transparent solid solution of intermediate composition which, together with the active layer, formed a waveguide for the laser radiation traveling in the medium with the wider band gap (InP). In the pulsed regime the minimum threshold current density was 930 A/cm² at room temperature.