THz quantum cascade lasers in magnetic fields

The current-voltage and emission characteristics of quantum cascade lasers of the range 3.3–3.7 THz, manufactured in Russia, were measured in magnetic fields up to 5 Tesla at helium temperature. When a magnetic field was applied, a decrease in threshold currents and a narrowing of the zone of intense generation from high currents side were observed. In the dependences of the radiation intensity on the magnetic field, a characteristic minimum was observed in magnetic fields in which the doubled cyclotron energy is compared with the energy of the radiation quantum, which indicates the inclusion of resonant scattering when the 2nd Landau level, related to the lower laser level, crosses the zero Landau level, related to the upper laser one.