The birefringent spin-laser as a system of coupled harmonic oscillators

TL;DR

This paper models birefringent spin-lasers as coupled harmonic oscillators, providing analytical insights into their ultrafast polarization modulation capabilities and exploring new operational regimes.

Contribution

It introduces a simplified real-quantity model for birefringent spin-lasers, revealing their dynamics as coupled oscillators and predicting new operational regimes.

Findings

Model agrees with intensity-equation description

Predicts new operational regimes

Elucidates weak and strong coupling differences

Abstract

Adding spin-polarized carriers to semiconductor lasers strongly changes their properties and, through the transfer of angular momentum, leads to the emission of circularly polarized light. In such spin-lasers, the polarization of the emitted light can be modulated an order of magnitude faster than its intensity in the best conventional lasers. This ultrafast operation in spin-lasers relies on large linear birefringence, usually viewed as detrimental in spin and conventional lasers, which couples the two linearly polarized emission modes. We show that the dynamical properties of birefringent spin-lasers under intensity and polarization modulation are accurately described as coupled harmonic oscillators. Our model agrees with the intensity-equation description which, unlike the common complex field components describing the role of birefringence in laser dynamics, uses simpler real quantities and allows analytical solutions. We further predict unexplored operation regimes and elucidate the difference between the weak and strong coupling in spin-lasers.