Electroluminescence and absorption spectra of low-optical-loss semiconductor lasers based on InGaAs/AlGaAs/GaAs QW heterostructures

Abstract

Spontaneous emission, optical loss, and gain spectra of a laser heterostructure with a quantum-well InGaAs active region have been studied at various optical and electrical pumping levels. It is shown that carrier accumulation in the active region under open-circuit conditions for the photocurrent leads to disappearance of the long-wavelength edge peak in the absorption spectrum. It is found that flowing photocurrent precludes accumulation of photogenerated carriers, with the result that the absorption spectrum retains its shape, irrespective of the optical pumping level. It is shown that many-particle effects of carrier interaction lead to a temperature-unrelated narrowing of the band gap in the InGaAs quantum-well active region by up to 30 meV and to tailing of the long-wavelength edge of the gain spectrum. As a result, a spectral range can be found for mesa-stripe laser diodes in which the gain in the region under the stripe contact is positive and the loss in passive regions is close to zero.