Measurement of the Azimuthal Angle Dependence of Third Harmonic Generation from Narrow-gap Semiconductor Surfaces

Reflection type measurements were performed on narrow-gap semiconductors such as InSb and InAs bulk samples for harmonic generation using intense terahertz pulses from free electron laser. We successfully measured the characteristic azimuthal angle dependence of the third harmonic generation (THG). The results show cos3θ and cos6θ dependence at different polarization layouts for InAs(111).

I. INTRODUCTION

NONLINEAR optical responses are involved in a number of processes such as two-photon absorption, optical parametric amplification, self-focusing, and Kerr effect. In order to study nonlinear optical responses in the terahertz (THz) region, high-intensity THz lasers are needed. Recently, high-intensity THz lasers have been under continuous development. Many researches on terahertz application including nonlinear optical responses were actively performed [1]-[45].