The effect of spontaneous emission on the dynamical operation of spin lasers.

Through angular momentum conservation, injecting spin-polarized carriers in lasers offers control of the helicity of emitted light and room-temperature spintronics applications, beyond magnetoresistence [1]. The push to scale down such spin lasers is accompanied by an enhanced contribution of spontaneous emission, usually assumed to be negligibly small. With a current injection required for the onset of lasing, there is a striking change from incoherent to coherent emitted light. However, in scaled-down lasers with a large spontaneous emission, this transition is blurred and even identifying the lasing threshold is a challenge [2]. The resulting changes with spontaneous emission strongly modify not only the steady-state [2], but also the dynamical operation of spin lasers, which is crucial for their applications [1]. We explore here various trends in this dynamical operation and provide guidance for an optimized design of scaled-down spin lasers.

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

[2] G. Xu, K. Patel, and I. Zutic, Appl. Phys. Lett. in press