Quantum model of gain in phonon-polariton lasers

TL;DR

This paper presents a quantum model for phonon-polariton laser gain, elucidating the interactions between electrons and phonons in quantum wells, and enabling optimization of laser designs across various materials.

Contribution

It introduces a comprehensive quantum theoretical framework for calculating phonon-polariton laser gain, incorporating matter excitations and dielectric effects, which was not previously available.

Findings

Provides a physical insight into phonon-polariton interactions.

Allows determination of phonon and photon contributions to gain.

Applicable to diverse laser designs and materials.

Abstract

We develop a quantum model for the calculation of the gain of phonon-polariton intersubband lasers. The polaritonic gain arizes from the interaction between the electrons confined in a quantum well structure and the phonon confined in one layer of the material. Our theoretical approach is based on expressing the crucial matter excitations (intersubband electrons and phonons) in terms of polarisation densities in second quantisation, and treating all non-resonant polarisations with an effective dielectric function. The interaction between the electronic and phononic polarizations is treated perturbatively, and gives rise to stimulated emission of polartions in the case of inverted subbands. Our model provides a complete physical insight of the system and allows to determine the phonon and photon fraction of the laser gain. Moreover, it can be applied and extended to any type of designs and material systems, offering a wide set of possibilities for the optimization of future phonon-polariton lasers.