Multiple-wavelength diode laser superarray

A monolithic array of four diode laser arrays operating at four widely separated wavelengths over a 30 nm bandwidth is demonstrated. The multiple-wavelength superarray is fabricated from GaAs/AlGaAs separate-confinement laser material in which the thickness of the single-quantum-well active layer is laterally graded to control its effective bandgap. Lateral thickness control is achieved by using laser-induced desorption to selectively thin the epitaxial layer during the MOCVD growth cycle. Transmission electron microscopy is used to demonstrate the variation of the quantum-well thickness from approximately 8 to 13 nm across the 1-μm-long chip as a result of the desorption. Individually addressable subarrays containing 10 gainguided emitters are defined after growth by conventional proton bombardment and localized metallization. Optical performance characteristics of the superarray are presented and discussed