Enhanced third-order nonlinearity in semiconductors giving rise to 1 THz radiation

Third harmonic generation (THG) efficiency is shown to be a greatly enhance d at the onset of inelastic scattering of electrons on optic phonons. Scali ng experiments are performed on n-type InP at the pump wave frequency of 9. 43 GHz at 80 K. Monte Carlo modeling is employed for scaling the effect to the 3(rd) harmonic frequency of 1 THz. The THG efficiency in n-type GaAs an d InP as well as in the wurtzite phase of n-type InN and GaN compound cryst als is compared to that in n-type Si. The efficiency maximum is found to we aken due to the quasi-elastic scattering on acoustic phonons and elastic sc attering on ionized impurities. Nevertheless, the THG efficiency at 1 THz i n InP crystals cooled down to liquid nitrogen temperatures is predicted to be 2 orders of magnitude higher than the reference value of 0.1% experiment ally recorded up to now in n-type Si.