Intersubband polaritons with spin-orbit interaction

TL;DR

This paper explores how spin-orbit interactions in asymmetric quantum wells influence intersubband polaritons, revealing new spin-dependent excitations and potential for spin current generation in semiconductor microcavities.

Contribution

It introduces a detailed analysis of spin-orbit effects on intersubband polaritons, including the emergence of multiple polaritonic branches and spin current possibilities.

Findings

Multiple polaritonic branches due to spin-orbit interaction.

Finite photon momentum induces non-zero spin polarization.

Potential for spin current generation with long coherence length.

Abstract

We investigate intersubband polaritons formed in the asymmetric quantum well (AQW) embedded into the semiconductor microcavity and study the effects of spin-orbit interaction (SOI) acting on intersubband excitations. The spin-orbit interaction of Rashba and Dresselhaus type remove the spin degeneracy of electrons with finite value of in-plane momentum and allow four types of intersubband excitations. While optical spin-flip transitions are suppressed, the spectrum of elementary excitations shows the appearance of upper, lower and middle polaritonic branches based on spin-conserving transitions. The accounting of finite photon momentum leads to non-zero average spin projection of electronic ensemble in the first excited subband under cw excitation for both isotropic (Rashba) and anisotropic (Rashba and Dresselhaus) SOI. We predict the possibility of spin current generation in the considered systems with long coherence length.