Synthetic crystal rotation with spacetime metamaterials

TL;DR

This paper explores synthetic crystal rotations created through spatiotemporal modulations, enabling high-frequency rotational effects on light, revealing new light-matter interaction regimes and unique spectral features.

Contribution

It introduces a novel method to simulate crystal rotation using spatiotemporal modulations, breaking traditional symmetry constraints and enabling access to high-frequency rotational phenomena.

Findings

Observation of frequency/SAM locking in sidebands

Detection of negative frequency sidebands at high rotation frequencies

Demonstration of new light-matter interaction regimes

Abstract

The interaction of light with rotating bodies has been historically limited to rotation frequencies much smaller than optical frequencies. Here, we investigate synthetic crystal rotations, i.e., spatiotemporal modulations mimicking the rotation of an anisotropic crystal, which grant access to large rotation frequencies. Spatiotemporal modulations change the fundamental symmetries of the electromagnetic field, breaking temporal and rotation symmetries, but preserving a spatiotemporal rotation symmetry that enforces the conservation of a combination of energy and spin angular momentum (SAM). The scattering of optical pulses by synthetically rotating crystals results in spatiotemporal light with intra-pulse SAM changes. The frequency-domain response reveals sidebands with frequency/SAM locking, and negative frequency sideband transitions for large enough rotation frequencies. Our results highlight the qualitatively different light-matter interaction regimes accessed by synthetic rotations.