Microcavity with DBR mirrors for efficient THz emission from optically pumped GaP layer: Numerical analysis by the method of single expression

Electromagnetic modelling of THz wave emission from GaP layer imbedded in a Fabry-Perot micro-resonator formed by two DBR mirrors is performed. The frequency-domain modelling is carried out by the method of single expression. The modelling permits to reveal favourable DBR-GaP-DBR structure, where layers of DBRs adjacent to the amplifying GaP layer are layers of lower permittivity. Proper choice of DBR mirrors permits to attain an essential enhancement of THz radiation from an optically pumped GaP layer. Resonant emission takes place at frequencies coinciding with resonant transparency of Fabry-Perot microcavity with GaP layer serving as a spacer. Distributions of electric field and Poynting vector within two types of micro-resonators at THz emission wavelength are obtained by using the modelling approach. Simulation results for the field distribution allow explaining the physics of the given emitting structure.