# Unidirectional control of optically induced spin waves

## TL;DR

This paper demonstrates unidirectional control of optically induced spin waves in a crystal, using interference and polarization techniques, with numerical simulations showing potential for arbitrary spin wave manipulation.

## Contribution

It introduces a method for controlling spin wave directionality using optical interference and polarization, including phased array simulation for complex manipulation.

## Key findings

- Unidirectional spin wave propagation achieved with specific phase and spacing.
- Polarization helicity switches the spin wave propagation direction.
- Numerical simulation replicates arbitrary spin wave control using phased array methods.

## Abstract

Unidirectional control of optically induced spin waves in a rare-earth iron garnet crystal is demonstrated. We observed the interference of two spin-wave packets with different initial phases generated by circularly polarized light pulses. This interference results in unidirectional propagation if the spin-wave sources are spaced apart at 1/4 of the wavelength of the spin waves and the initial phase difference is set to pi/2. The propagating direction of the spin wave is switched by the polarization helicity of the light pulses. Moreover, in a numerical simulation, applying more than two spin-wave sources with a suitable polarization and spot shape, arbitrary manipulation of the spin wave by the phased array method was replicated.