Electro-optical modulation of terahertz beam by drifting space-charge domains in n-GaN epilayers

Abstract

Electro-optical modulation of a terahertz beam by drifting space-charge domains in n-GaN epilayers under pulsed electric field excitation was found and investigated at a temperature of 77 K. The free charge carrier contribution was observed as the attenuation of terahertz (THz) transmission whose value independently on THz beam polarization increased with the electric field, in the presence of drifting space-charge domains, up to 10%. The electro-optical contribution, on the other hand, was sensitive to beam polarization and demonstrated a nonlinear increase in THz transmission up to 50% under the external electric field up to 1.6 kV/cm, while higher field values led to an electrical breakdown of samples operating in the presence of drifting space-charge domain.