Terahertz Radiation from Electro-Optic Crystals

Abstract

With illumination by femtosecond laser pulses at an oblique incident angle, a semiconductor sample emits subpicosecond submillimeter-wave radiation¹. This phenomenon was interpreted as radiation from accelerated photocarriers in the surface depletion field1 and the dependence of the radiation on crystal rotation symmetry was explained as strong evidence of X ⁽³⁾ related optical rectification². More recently, quantum well structures have been used to limit the carrier transport. This allows examination of the mechanism of optical rectification as well as the study of electron coherent oscillations in a double-well potential³. To distinguish between the contribution from carrier transport and from optical rectification is crucial for a physical understanding of the origin of the radiation, as well as for realizing an intense THz source application.