Third harmonic generation by Bloch-oscillating electrons in a quasioptical array

We compute the third harmonic field generated by Bloch-oscillating electrons in a quasioptical array of superlattices under THz irradiation. The third harmonic power transmitted oscillates with the internal electric field, with nodes associated with Bessel functions in eEd/(h) over bar omega. The nonlinear response of the array causes the output power to be a multivalued function of the incident laser power. The output can be optimized by adjusting the frequency of the incident pulse to match one of the Fabry-Perot resonances in the substrate. Within the transmission-line model of the array, the maximum conversion efficiency is 0.1%. (C) 1999 American Institute of Physics. [S0003-6951(99)01215-2].