Photoluminescence characterization of a counterpropagating twin photons structure: hot carrier effects in AlGaAs

Abstract

Counterpropagating signal and idler twin photons can be produced via parametric fluorescence by a pump beam incident at a certain angle on top of a III–V semiconductor waveguide, as long as the refractive indices of the waveguide material for the two photons––determined by the thicknesses and alloy compositions of the layers––satisfy the necessary in plane phase matching condition. A specially designed AlGaAs/AlAs counterpropagating twin photons structure is characterized by temperature and pumping power density dependence photoluminescence spectroscopy. Under the present conditions of photoexcitation the spectra show all the typical characteristics of hot carrier luminescence. The relaxation of photoexcited carriers and formation of hot electron gas are analysed and discussed. From the dependence on pumping power density of the carrier temperature extracted from the slope of the high energy tail of the spectra, it is shown that the main relaxation path of the hot electron gas is via emission of LO-phonons at low temperatures.