Analysis of Terahertz Radiation Spectra in Multilayer GaAs/AlGaAs Heterostructures

The results of examination of the terahertz radiation spectra of multilayer GaAs/AlGaAs heterostructures synthesized on GaAs substrates are presented. The dependence of the radiation spectrum on the amplitude of the excitation current pulse and temperature dependences of the threshold lasing current and the radiation power of terahertz quantum cascade lasers with a double metallic waveguide, which were built on the basis of these structures, have been obtained. The maximum amplitude of the total radiation power is estimated at 28 μW in the range 3.25–3.32 THz at a temperature of 15 K. The spectral radiation density of the oscillator is measured. Changes in the mode content of radiation induced by the bias-current variation have been observed.