Ultrasonic control of terahertz radiation via lattice anharmonicity in LiNbO3

TL;DR

This paper introduces a tunable terahertz filter leveraging the resonant acousto-optic effect in LiNbO3, enabling continuous frequency tuning up to 4 THz through acoustic frequency variation.

Contribution

It presents a novel design for a THz filter based on lattice anharmonicity and the RAO effect, expanding tunability in the terahertz range.

Findings

Achieves tunability up to 4 THz via acoustic frequency control

Demonstrates the role of cubic and quartic anharmonicities in the RAO effect

Discusses interference effects between anharmonicities

Abstract

We propose a novel tunable terahertz (THz) filter using the resonant acousto-optic (RAO) effect. We present a design based on a transverse optical (TO) phonon mediated interaction between a coherent acoustic wave and the THz field in LiNbO3. We predict a continuously tunable range of the filter up to 4 THz via the variation of the acoustic frequency between 0.1 and 1 GHz. The RAO effect in this case is due to cubic and quartic anharmonicities between TO phonons and the acoustic field. The effect of the interference between the anharmonicities is also discussed.