Frequency Vectoralization and Frequency Birefringence

TL;DR

This paper introduces the concepts of frequency vectoralization and frequency birefringence, analyzing how temporal transitions in media affect wave frequency and direction, with implications for wave control and diffraction phenomena.

Contribution

It presents a novel theoretical framework linking temporal media transitions to frequency and directional properties, including the concepts of frequency vectoralization and birefringence.

Findings

Temporal media transitions induce directional frequency properties.

Anisotropic temporal interfaces cause diffraction in spatial and spectral domains.

The paper establishes an analogy between spatial and temporal interfaces.

Abstract

In view of momentum continuity at a temporal slab, it is shown that instantaneous switching of an isotropic medium to an anisotropic medium offers the incident frequency a directional property- a counterintuitive process which is called frequency vectoralization. By expressing the dispersion diagrams before and after the temporal transition, a general analogy between spatial and temporal interfaces is given and the concept of frequency birefringence, i.e. double frequency jump, will be explained. Furthermore, it will be shown that an anisotropic temporal interface diffracts a monochromatic beam in both the spatial and spectral domains.