Terahertz oscillator based on nonlinear frequency conversion in a double vertical cavity

The feasibility of producing a vertical-cavity laser that operates in the far IR region and is based on the three-wave mixing due to the lattice nonlinearity of a GaAs/AlGaAs system is analyzed. It is shown that the use of a double Bragg cavity with the parameters tuned both to high-frequency oscillations (sources of nonlinear polarization) and to the difference frequency allows one to raise the intensity of the radiation in the far IR region. The power density of the radiation at a wavelength of 49.5 μm equals approximately 5 × 10^?4 μW/μm² at a drive current density of 5 kA/cm². It is suggested that a drive current should be supplied with the use of intercavity contacts, to be located in the vicinity of a node in the difference mode; then, the absorption of radiation by free charge carriers will be reduced to a minimum.