UP-conversion of terahertz radiation induced by photon drag effect

An all-optical approach to convert terahertz radiation (THz, wavelength λ1) into infrared (IR, peak wavelength λ2) is presented. We show that this up-conversion process is due to the photon drag effect induced by the THz radiation in intrinsic narrow-gap semiconductors followed by spatial redistribution of current carriers and band-to-band radiative recombination. The process results in non-selective high-speed (ns range rise/fall times) IR imaging of positive (conventional luminescence) and/or negative (negative luminescence) contrasts. Estimates made for an InSb pixelless converter at View the MathML source and moderate THz intensity (∼kW/cm2) show that this up-conversion process (with λ1/λ2>102) can be observed with a conventional thermal imaging camera.