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arXiv · 2601.13961

Understanding Optical Anisotropy in Multilayer γ-InSe and ε-GaSe

Jason Lynch·Zexuan Liu·Sergiy Krylyuk·Huairuo Zhang·Albert Davydov·Deep Jariwala
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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 γ-InSe and ε-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 γ-InSe and ε-GaSe enables the accurate simulation of these media, allowing for the design of high-performance, ultra-compact optoelectronic devices.

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Jason Lynch, Zexuan Liu, Sergiy Krylyuk, Huairuo Zhang, Albert Davydov, Deep Jariwala. 2026-01-20. Understanding Optical Anisotropy in Multilayer γ-InSe and ε-GaSe. https://arxiv.org/abs/2601.13961

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