# Generation of unipolar half-cycle pulse via unusual reflection of a single-cycle pulse from an optically thin metallic or dielectric layer

## TL;DR

This paper introduces a novel reflection process from thin layers that enables the formation of approximately unipolar half-cycle optical pulses by controlling charge velocity, differing from traditional mirror reflection.

## Contribution

It proposes a simple method to generate unipolar half-cycle pulses via reflection from thin layers, leveraging charge velocity rather than acceleration, which is a novel approach.

## Key findings

- Unipolar pulses can be generated through reflection from thin layers.
- Charge velocity, not acceleration, determines emitted field in this process.
- The method enables unusual transformations of few-cycle light pulses.

## Abstract

We present a significantly different reflection process from an optically thin flat metallic or dielectric layer and propose a strikingly simple method to form approximately unipolar half-cycle optical pulses via reflection of a single-cycle optical pulse. Unipolar pulses in reflection arise due to specifics of effectively one-dimensional pulse propagation. Namely, we show that in considered system the field emitted by a flat medium layer is proportional to the velocity of oscillating medium charges instead of their acceleration as it is usually the case. When the single-cycle pulse interacts with linear optical medium, the oscillation velocity of medium charges can be then forced to keep constant sign throughout the pulse duration. Our results essentially differ from the direct mirror reflection and suggest a possibility of unusual transformations of the few-cycle light pulses in linear optical systems.