Polarization bistability of vertical-cavity surface-emitting lasers under Larmor precession of electron spins

Polarization bistability of vertical-cavity surface-emitting lasers (VCSELs) is the situation in which two orthogonal linear polarization states can selectively and stably exist for a single operation condition (e.g., injected current and temperature) and provide switching between the two orthogonal linear polarizations and complex polarization dynamics. This is attractive for photonic computing in the sense that the complexity of a nonlinear node can be enhanced. However, polarization bistability is considered inherent to the material properties and cavity structure of VCSELs, which makes it difficult to optimize the complex dynamics to achieve the best computational performance. We show that the polarization bistability of VCSELs can be controlled by manipulating electron spins in the active region. We achieve such manipulation by using the transverse external magnetic field, i.e., Larmor precession of electron spins. We reveal that the control of the Larmor-precession frequency induces a polarization switching and its hysteresis behavior of VCSELs without changing current, heat, and external light, demonstrating that the manipulation of electron spins can control polarization bistability of VCSELs. This finding is a novel phenomenon in spin-controlled VCSELs, which will contribute to the development of interdisciplinary research fields in computing between photonics and spintronics.