Properties of MO-CVD-grown GaAs/GaAlAs lasers as a function of stripewidth

Abstract

Gain-guided lasers grown by metal-organic chemical vapor deposition (MO-CVD) are studied experimentally and theoretically with conducting stripewidth <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> as a variable. Stripe geometry lasers of 2, 4, 6, and 8 μm width, delineated by shallow proton implantations. Are very uniform relative to those grown by liquid-phase epitaxy (LPE). Measured and calculated thresholds are virtually independent for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> for the low-spreading resistance devices studied, whereas differential quantum efficiency decreases monotonically with diminishing <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> . Computed charge density distributions peak most sharply for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> =2 μm, and only for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> -8 μm do they become sufficiently broad so that kinks occur below 15 mW output power levels. Spectra spread inversely with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> and shift to shorter wavelengths as <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> is decreased. Measured and calculated far-field radiation patterns agree well and change continuously from a single central-peaked lobe for <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> =8 μm to one with two lobes at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> =2 μm. Near-field intensity patterns depend only weakly on <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> between 2 and 8 μm, but computed phases vary greatly with <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</i> and, as a result of charge-induced antiguiding, account directly for the far-field results.