Understanding Optical Anisotropy in Multilayer {\gamma}-InSe and {\epsilon}-GaSe
Abstract
Low-dimensional media have exhibited optical anisotropy that is unachievable in traditional 3D media due to the asymmetry of their strong, in-plane covalent bonds and weak out-of-plane van der Waals interactions. As a result, 2D media are promising building blocks for ultrathin devices such as polarimeters, polarized light sources, and active polarizers. III-VI semiconductors possess a rare property in the class of multilayered semiconductors, which is that their fundamental excitons are oriented out-of-plane. This allows them to exhibit phenomena such as transparency in the visible range while also being emissive in the visible and near-infrared ranges. Here, we report the first experimental values for the anisotropic refractive indices of {\gamma}-InSe and {\epsilon}-GaSe, and we observe the effects of the out-of-plane excitons on the c-axis refractive index. It is found that both materials exhibit moderate optical anisotropy for multilayered semiconductors. The complex, anisotropic refractive index of {\gamma}-InSe and {\epsilon}-GaSe enables the accurate simulation of these media, allowing for the design of high-performance, ultra-compact optoelectronic devices.
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Cite
@article{arxiv.2601.13961,
title = {Understanding Optical Anisotropy in Multilayer {\gamma}-InSe and {\epsilon}-GaSe},
author = {Jason Lynch and Zexuan Liu and Sergiy Krylyuk and Huairuo Zhang and Albert Davydov and Deep Jariwala},
journal= {arXiv preprint arXiv:2601.13961},
year = {2026}
}