Room temperature spin injection into commercial VCSELs at non-resonant wavelengths

TL;DR

This paper demonstrates successful room temperature spin injection into commercial VCSELs at non-resonant wavelengths, achieving measurable circular polarisation and extending the Spin-Flip Model to match experimental results.

Contribution

It presents the first successful optical spin injection into a commercial VCSEL at non-resonant wavelengths and extends the Spin-Flip Model for realistic excitation conditions.

Findings

Maximum 20% circular polarisation at 794 nm

Reduced polarisation at 810 nm due to longer wavelength

Theoretical model accurately reproduces experimental trends

Abstract

Spin lasers leverage electron spin-polarisation to control photon polarisation, offering the potential for lower thresholds, rapid modulation, and all-optical data processing. We report successful spin injection into a commercial Vertical Cavity Surface Emitting Laser (VCSEL) using optical pumping at wavelengths of 794 nm and 810 nm. Maximum circular polarisation achieved was about 20% at 794 nm, whereas this falls to 5% with exciting at 810 nm. We attribute this to reduced spin injection due to the longer excitation wavelength in line with previous measurements on quantum wells under optical orientation. We extend the Spin-Flip Model (SFM) to account for realistic excitation conditions and find our theoretical analysis accurately reproduces experimental trends.