Time-refraction near the critical angle and angular streaking with attosecond resolution [Invited]

• DOI: 10.1364/ome.553662
• Publication Date: 2025-04-18T17:00:25Z
• Authors: Colton Fruhling; Mustafa Goksu Ozlu; Ohad Segal; Wallace Jaffray; Sven Stengel; Marcello Ferrera; Alexandra Boltasseva; Mordechai Segev; Vladimir M. Shalaev

We study the time-refraction of optical waves as they propagate through a time-varying slab and find the frequency shift associated with the abrupt change in the refractive index. We discover a geometrical mechanism responsible for an ultrafast blueshift followed by a redshift, occurring while the refractive index is increased monotonically. Furthermore, we find high sensitivity to incident angles near the traditional critical angle and unravel a new critical angle that varies in time. Finally, we introduce an innovative concept of a streak camera design that utilizes ultrafast nonlinearities in time-varying media and offers attosecond resolution capabilities.