Ultrafast spin-lasers.
basic_science · Level V
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- Record sourced from PubMed, PMID 30944471.
- Also identified by DOI 10.1038/s41586-019-1073-y.
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Abstract
Lasers have both ubiquitous applications and roles as model systems in which non-equilibrium and cooperative phenomena can be elucidated<sup>1</sup>. The introduction of novel concepts in laser operation thus has potential to lead to both new applications and fundamental insights<sup>2</sup>. Spintronics<sup>3</sup>, 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<sup>3</sup> and conventional lasers<sup>4</sup>. 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.