Spatio-Temporal Light Springs: An Exotic State of Light to Explore Novel Laser-Plasma Interactions

It is well established that electromagnetic waves are capable of carrying both a spin and an orbital angular momentum (OAM). When two OAM beams of different wavelengths and different mode numbers are superimposed, an exotic state of light is generated. This superposition of 2-color, 2-OAM beams has been colloquially referred to as a "light spring" in reference to the unique property of having a 3-dimensional, spring-like intensity profile.

In this work, we investigate the interaction of light springs with underdense plasma, and demonstrate a novel method for generating relativistic strength light springs. We derive conditions such that the light spring both resonantly couples with the plasma and self-guides as it propagates through the plasma. Simulations conducted using FBPIC show angular momentum coupling between the light spring and plasma, indicating that magnetic fields on the order of 100's Tesla can be generated via the inverse Faraday effect using laser powers less than 5TW.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344 and supported by the Natural Sciences and Engineering Research Council of Canada research grant number RGPIN-2019-05013. This work is also supported by the NSF under Grant No. PHY-1753165.