Giant asymmetric self-phase modulation in superconductor thin films

TL;DR

This paper demonstrates that superconducting thin films exhibit a giant, asymmetric self-phase modulation effect at low light intensities, leading to significant spectral shifts in the THz regime, with potential applications in ultrafast optics.

Contribution

The authors develop a novel theoretical model combining TDGL equations and electrodynamics to describe asymmetric SPM in superconductors, revealing effects not previously understood.

Findings

Strong, asymmetric SPM occurs at low intensities in superconductors.

Significant redshifted spectral broadening develops within nanometers.

Theoretical simulations confirm the effect in the THz regime.

Abstract

Self-phase modulation (SPM) of light pulses is found to occur strongly, at low incident intensities, in the coupling of light with superconductors. We develop a theory from a synthesis of the time-dependent Ginzburg-Landau (TDGL) equation and basic electrodynamics which shows the strongly non-linear phase accumulated in the interaction. Unusually, the SPM of the pulse in this system is found to be highly asymmetric, producing a strongly redshifted spectrum when interacting with a superconducting thin film, and it develops in just a few nanometers of propagation. In this paper we present theoretical results and simulations in the THz regime, for both hyperbolic secant and supergaussian-shaped pulses.