Spin-Lasers as Coupled Harmonic Oscillators

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. This opens important opportunities for spintronics beyond magnetoresistance [1]. In such spin-lasers, we find that the polarization of the emitted light can be modulated an order of magnitude faster than its intensity in the best conventional lasers [2]. This ultrafast operation in spin-lasers relies on large linear birefringence, which couples the two linearly polarized emission modes [2]. Unlike common modeling of lasers as a harmonic oscillator [1], here it is crucial to introduce a model of coupled harmonic oscillators [3]. Remarkably, our model not only accurately describes the main trends of modulated spin-lasers [2-4] but also predicts their unexplored operation regions [3].

[1] I. Zutic et al., Solid State Commun. 316-317, 113949 (2020)

[2] M. Lindemann et al., Nature 568, 212 (2019)

[3] V. Labinac et al., Phys. Rev. B 112, 075303 (2025)

[4] G. Xu et al., Phys. Rev. B 103, 045306 (2021)