Tunable Directional Filter for Mid-Infrared Optical Transmission Switching

TL;DR

This paper introduces a thermally tunable multilayer IR filter using VO2 that enables fast, reversible optical switching by controlling spectral and angular IR transmission with temperature-dependent phase changes.

Contribution

The paper presents a novel multilayer dielectric filter design that leverages VO2's phase change for efficient, reversible IR optical switching and filtering.

Findings

Achieves narrowband IR transmission at near-normal angles at low temperatures.

Blocks IR transmission at high temperatures due to VO2 metallic phase.

Potential applications in optical communications as a dual filter and switch.

Abstract

Controlling the spectral and angular response of infrared (IR) radiation is a challenging task of paramount importance to various emerging photonic applications. Here, we overcome these problems by proposing and analyzing a new design of a tunable narrowband directional optical transmission filter. The presented thermally controlled multilayer filter leverages the temperature dependent phase change properties of vanadium dioxide (VO2) to enable efficient and reversible fast optical switching by using a pump-probe laser excitation setup. More specifically, transmission is blocked for high intensity probe lasers due to the VO2 metallic properties induced at elevated temperatures while at low probe laser intensities high transmission through the filter occurs only for a narrowband IR range confined to near normal incident angles. The proposed multilayer composite dielectric filter is expected to have applications in optical communications, where it can act as dual functional infrared filter and optical switch.