Ultrafast spin-lasers

Lindemann, M. and Xu, G. and Pusch, T. and Michalzik, R. and Hofmann, M.R. and Žutić, I. and Gerhardt, N.C.

Volume: 568 Pages: 212-215
DOI: 10.1038/s41586-019-1073-y
Published: 2019

Lasers have both ubiquitous applications and roles as model systems in which non-equilibrium and cooperative phenomena can be elucidated 1 . The introduction of novel concepts in laser operation thus has potential to lead to both new applications and fundamental insights 2 . Spintronics 3 , in which both the spin and the charge of the electron are used, has led to the development of spin-lasers, in which charge-carrier spin and photon spin are exploited. Here we show experimentally that the coupling between carrier spin and light polarization in common semiconductor lasers can enable room-temperature modulation frequencies above 200 gigahertz, exceeding by nearly an order of magnitude the best conventional semiconductor lasers. Surprisingly, this ultrafast operation of the resultant spin-laser relies on a short carrier spin relaxation time and a large anisotropy of the refractive index, both of which are commonly viewed as detrimental in spintronics 3 and conventional lasers 4 . Our results overcome the key speed limitations of conventional directly modulated lasers and offer a prospect for the next generation of low-energy ultrafast optical communication. © 2019, The Author(s), under exclusive licence to Springer Nature Limited.

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