Complex permittivity of a biased superlattice

TL;DR

This paper investigates the complex permittivity of a biased superlattice under electric field, revealing potential THz gain and conditions for stimulated emission in waveguide structures.

Contribution

It provides a detailed calculation of the complex dielectric permittivity beyond the Born approximation, considering broadening mechanisms in biased superlattices.

Findings

Detectable THz gain below resonance in low-doped GaAs superlattices.

Conditions for stimulated emission in waveguide structures.

Complex permittivity calculated beyond the Born approximation.

Abstract

Intersubband response in a superlattice subjected to a homogeneous electric field (biased superlattice with equipopulated levels) is studied within the tight-binding approximation, taking into account the interplay between homogeneous and inhomogeneous mechanisms of broadening. The complex dielectric permittivity is calculated beyond the Born approximation for a wide spectral region. A detectable gain below the resonance is obtained for the low-doped $GaAs$-based biased superlattice in the THz spectral region. Conditions of the stimulated emission regime for metallic and dielectric waveguide structures are discussed.