View in EDS

Giant photorefractive and photoexpansion effects in a van der Waals semiconductor.

Saved in:

Bibliographic Details
Title:	Giant photorefractive and photoexpansion effects in a van der Waals semiconductor.
Authors:	Minnekhanov, Anton A.¹, Ermolaev, Georgy A.¹, Tsapenko, Alexey P.¹, Fradkin, Ilia M.¹, Tselikov, Gleb I.¹, Toksumakov, Adilet N.¹, Slavich, Aleksandr S.¹, Mazitov, Arslan B.¹, Smirnov, Sergey A.¹, Orekhov, Nikita D.¹, Kruglov, Ivan A.¹, Ivanov, Sergei A.¹, Radko, Ilya P.¹, Vyshnevyy, Andrey A.¹, Arsenin, Aleksey V.¹, Novoselov, Kostya S.^2,3,4 kostya@nus.edu.sg, Volkov, Valentyn S.¹ vsv@xpanceo.com
Source:	Proceedings of the National Academy of Sciences of the United States of America. 3/31/2026, Vol. 123 Issue 13, p1-9. 9p.
Subjects:	Photorefractive effect, Arsenic sulfide, Two-dimensional materials (Nanotechnology), Nanophotonics, Optical modulation, Nanopatterning
Abstract:	Nanophotonics relies on precise nanoscale structuring, yet conventional fabrication techniques remain complex and costly. Layered van der Waals (vdW) materials, with their intrinsic anisotropy and high refractive indices, offer a promising route toward simplified nanostructuring and tunable optical functionality. However, no vdW material has previously been shown to exhibit a strong photorefractive effect—a key requirement for light-based modulation. Here, we report a giant photorefractive response (Δn up to 0.3) in crystalline arsenic trisulfide (As2S3), observed at low optical intensities. In addition to refractive-index modulation, light exposure enables controlled thickness tuning of As2S3. The material exhibits a giant photoexpansion of up to 7%, depending on the illumination intensity, which may originate from light-induced generation of point defects, consistent with molecular-dynamics modeling. Building on this photoexpansion effect, we introduce a maskless nanopatterning technique based on continuous-wave laser writing, achieving ~500 nm pitch (~50,000 dpi) without the need for ultrafast lasers. The combination of high photosensitivity, anisotropy, ease of exfoliation and transfer, and optical transparency positions vdW As2S3 as a practical platform for integrated photonics, adaptive optics, reconfigurable photonic elements, and dense optical encoding. [ABSTRACT FROM AUTHOR]
	Copyright of Proceedings of the National Academy of Sciences of the United States of America is the property of National Academy of Sciences and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database:	Engineering Source

Description
Abstract:	Nanophotonics relies on precise nanoscale structuring, yet conventional fabrication techniques remain complex and costly. Layered van der Waals (vdW) materials, with their intrinsic anisotropy and high refractive indices, offer a promising route toward simplified nanostructuring and tunable optical functionality. However, no vdW material has previously been shown to exhibit a strong photorefractive effect—a key requirement for light-based modulation. Here, we report a giant photorefractive response (Δn up to 0.3) in crystalline arsenic trisulfide (As2S3), observed at low optical intensities. In addition to refractive-index modulation, light exposure enables controlled thickness tuning of As2S3. The material exhibits a giant photoexpansion of up to 7%, depending on the illumination intensity, which may originate from light-induced generation of point defects, consistent with molecular-dynamics modeling. Building on this photoexpansion effect, we introduce a maskless nanopatterning technique based on continuous-wave laser writing, achieving ~500 nm pitch (~50,000 dpi) without the need for ultrafast lasers. The combination of high photosensitivity, anisotropy, ease of exfoliation and transfer, and optical transparency positions vdW As2S3 as a practical platform for integrated photonics, adaptive optics, reconfigurable photonic elements, and dense optical encoding. [ABSTRACT FROM AUTHOR]
ISSN:	00278424
DOI:	10.1073/pnas.2531552123