Mid-wave and Long-wave IR Linear Dichroism in a Hexagonal Perovskite Chalcogenide

TL;DR

This paper introduces Sr1+xTiS3, a non-toxic, earth-abundant material with strong broadband linear dichroism in mid-wave and long-wave IR, promising for cost-effective IR optical applications.

Contribution

It reports the synthesis and optical characterization of Sr1+xTiS3, a novel anisotropic perovskite chalcogenide with significant IR linear dichroism, expanding materials options for IR photodetectors.

Findings

Observed two distinct IR absorption edges at ~2.5 μm and ~5 μm.

Demonstrated strong broadband linear dichroism with a ratio up to 22.

Produced high-quality single crystals suitable for optical studies.

Abstract

Mid-wave infrared (IR) and long-wave IR spectral ranges are of growing interest in various applications such as thermal imaging, thermography-based remote sensing, and night vision. Materials widely used for IR photodetectors in this regime include cadmium mercury telluride alloys and nanostructures of compound semiconductor. The materials development for IR optics will drive down the cost of IR optical systems and enable larger scale deployment. Here, we report a mid-wave IR responsive material composed of earth abundant and non-toxic elements, Sr1+xTiS3. It has a highly anisotropic quasi-one-dimensional structure similar to hexagonal perovskites. We grew large, high quality single crystals and studied its anisotropic optical properties. We observed two distinct optical absorption edges at ~2.5 um and ~5 um, respectively, for linear polarizations along two principal axes. The material demonstrated strong and broadband linear dichroism spanning mid-wave IR and long-wave IR, with a dichroitic ratio of up to 22.