A team of scientists has uncovered a crystal that can be reshaped and programmed using ordinary light, opening a new path for building optical technology.
Researchers at the XPANCEO Emerging Technologies Research Center, working alongside Nobel Laureate Prof. Konstantin Novoselov (University of Manchester and the National University of Singapore), have identified unusual optical behavior in arsenic trisulfide (As2S3), a crystalline van der Waals semiconductor. Their work shows that this material can be permanently altered by light and even shaped at the nanoscale using simple continuous-wave (CW) light. This approach eliminates the need for expensive cleanroom lithography or advanced femtosecond laser systems.
Understanding Refractive Index and Photorefractivity
A key property behind this discovery is the refractive index, which determines how much a material bends or slows light. Materials with higher refractive indices are better at guiding light through optical systems. In some cases, light itself can change this property. This effect is called photorefractivity, where exposure to light modifies the refractive index.
Crystalline As2S3 shows this effect even under low-intensity ultraviolet light. In the study, the material exhibited a very large light-induced refractive index change (up to Δn ≈ 0.3). This is significantly higher than what is typically reported for well-known photorefractive materials such as BaTiO3 or LiNbO3.
Writing Optical Functions Directly With Light
Materials with strong photorefractive responses allow optical functions to be created directly inside the material using light. Instead of relying on complex manufacturing steps, light can define how the material interacts with optical signals.
This capability supports a wide range of applications. It can be used to form tiny structures that guide light in telecommunications equipment, create diffractive elements for sensors and imaging systems, and produce hologram-like features for security and authentication, where the optical pattern itself serves as a unique identifier.
Nanoscale Patterns and Optical Fingerprints
In As2S3, these effects operate at extremely fine scales. The strong change in refractive index enables the formation of highly detailed patterns embedded within the transparent material. These patterns can act as “optical fingerprints” that are difficult to replicate, making them useful for anti-counterfeiting and traceability.
To demonstrate this level of control, researchers used a standard laser to “sculpt” a microscopic monochromatic portrait of Albert Einstein on a thin flake of the material, with points spaced 700 nanometers apart. Additional experiments showed even higher resolution (to ~50,000 dots per inch, which corresponds to 500 nanometers between points). The patterns show strong contrast because of the light-induced refractive index change, allowing them to be clearly read using optical methods.
Light-Driven Materials and Future Photonics
“The discovery of new functional materials, particularly within the unique family of van der Waals crystals, is the fundamental engine for moving the entire field of photonics forward. Developing sophisticated optical devices, such as advanced smart contact lenses, is a deeply complex challenge that requires a solid foundation in fundamental materials science. In these systems, the material itself is the key component that determines what is physically possible. By identifying natural crystals with this level of sensitivity, we are effectively providing the essential building blocks for a new generation of technology that is driven entirely by light rather than electricity,” said Valentyn Volkov, Founder and Chief Technology Officer at the XPANCEO Emerging Technologies Research Center
Expanding Crystals Enable New Optical Devices
Beyond changing its optical properties, As2S3 also undergoes physical expansion when exposed to light. The material can expand by up to 5%, which allows researchers to directly form structures such as microlenses and gratings on its surface.
These capabilities are important for developing wide field-of-view waveguides used in augmented reality glasses and smart contact lenses. In addition, the material’s sensitivity makes it a strong candidate for photonic circuits and nanoscale sensors. Together, these properties represent a significant advance in the ability to control and manipulate light for future technologies.
Reference: “Giant photorefractive and photoexpansion effects in a van der Waals semiconductor” by Anton A. Minnekhanov, Georgy A. Ermolaev, Alexey P. Tsapenko, Ilia M. Fradkin, Gleb I. Tselikov, Adilet N. Toksumakov, Aleksandr S. Slavich, Arslan B. Mazitov, Sergey A. Smirnov, Nikita D. Orekhov, Ivan A. Kruglov, Sergei A. Ivanov, Ilya P. Radko, Andrey A. Vyshnevyy, Aleksey V. Arsenin, Kostya S. Novoselov and Valentyn S. Volkov, 27 March 2026, Proceedings of the National Academy of Sciences.
DOI: 10.1073/pnas.2531552123
Never miss a breakthrough: Join the SciTechDaily newsletter.
Follow us on Google and Google News.
2 Comments
very good
THE NEW ARE TERMS OF-(BIO-REALITY) IS COMPLETED ALL FORMS OF INCREASED INTO TECHNOLOGICAL-BREAK-THROUGHTS ISSUES ARE NOT FOLLOWING THESE AREAS”: A-DATA-BASE BECAUSE ITS NEW TYPES OF ENERGY-ARE PRE-SUBJECTIONS ARE DUE THESE INTO THESE COMPREHENSION:”THE NEW TYPES:(INFORMATIONS-TECHNOLOGY(BIO-CBYER-SPACE )(BIO-TECHNOLOGY) ARE NEVER-THE-LESS ARE THE FUTURE INTO ALL THESE FEATURES NOTHING NOTED BY FEATURES OF CONNECTIONS ARE HALLORAPHIC-IMAGING ISSUES(ENERGY-CONSERVASTION OFTEN DUE TO THE FOLLOWING”EVEN”THEORTIACAL”OFTEN” COMPLETED BY ALL SEQUENCES BY DESCRIPTIONS ARE ASSUMPTIONS YET DEVELOPEDBY ISSUES ASSUMPTIONSACCUMLATED INTO THE ISSUES ARE COMLETED FACTORS ACCOMPLISHED BY EACH INTO THESE AREAS ACCOUNTS TO MATAHEMATICAL-COMPUATIONS DESCRIPTIONS OF AMOUNTS “EMPHASIS”ARE THE FOLLOWING DEFINITNSS COLLECTIONS DESCRIPTIONS INTO THESE QUESTIONS BETTER DESCRIPTIONS INTO ALL PRESPCTIVES NOT REMAINS ASSUMPTIONS OF AREAS COMPLETES A SOURCES THESE QUESTIONS DESCRIPTION & “THESE COLLECTIONS ARE SOLAR-PANELS INTO THESE QUESTIONS NUMBERICAL ARE ASSUMPTIONS INTO THEORIES OFTEN REWINDS INTO THE MASSIVE AND COLLECTIONS OF GENERAL ISSUES OF THE FOLLOWING DETERMINATIONS FORMED BY EAVERYTHING NOT EVERTIME FOR EACH INTO THESE QUESTIONS ARE COMPLETED BY EACH “TIME-IS-SPACE BUT GOD IS EVERTHING BUT HUMANITY IS BEYOND. THE FOLLOWINGS AND SERIES ARE COMPREHENED NOT REQUESTS OF IL-LOGCIAL INTO THESE COMPREHENISONS INTO THESE QUESTIONS INTO THESE QUESTIONS “ALL REALITY FORMS-UPON ITS OWN EVERYTHING: THE ASSUMPTIONS NOTED BY EACHOF QUESTIONS THESE QUESTIONS ARE DESCRIPTIONS ARE DEVELOPES A SIMPLE FOUNADTIONS INTO ITS QUESTIONS :THE FEATURES OF TRIGONMETRY NEW CODES OF BASIC/INTERMEDAET/ADVANCED NUMERAICAL-VALUES (DIAMOUNDS/HEXAGON/OCTEGON/TRANGLE/CUBE/ &RECTANGULAR (SUMMARIZES OF CONNECTIONS NOTED NOT IMPROVISED WITH THE NEGATIVE ISSUES ARE DESCRIPTIONS ARE DEPENDS ACCOMPLISHED BECAUSE A REASONING COLLECTIONS ARE DESCRIPITONS ARE RESULTS ARE COMPLETED INTO THESE QUESTIONS.THE FOLLOWING FACTORS FUNDAMAENTALS(F\./\F/.\F)THE WIRE CONENCTIONS INTO SPACE SHUTTLE THE (SOLAR-SYSTEMS) ARE BATTERIES INTO THESE QUESTIONS ARE COMPLETED BY EACH -CODES.THE FEATURES OF REASONING DUE TO THESE COMBINATIONS INNER-CODE DESCRIBES NOT REDCUTIONS AND DESCRIPTIONS ASSUMPTIONS ARE DESCRIPTIONS DECREASED VALUES INTO THESE QUESTIONS MEASURES A SIMPLE RESULTS OF ALL-SIMPLE ISSUES ASSUMPTIONS DUE TO THE FOUNDATIONS NOT ONLY FUNDAMENTALS ARE DESCRIPITONS. ALLTECHNOLOGICAL INTO THESE INTO ASSUMPTIONS ARE COLLECTIONS INTO THESE COLLECTIONS DECREASED BY VALUES OF INCREASED SERIES: THE FOUNDATIONS ARE INNER-CORES OF WHY?WHEN?HOW?THEN)/COULD/SHOULDS/WOULD NEVER REPEATS S ARE NARROW-MINDED AND DESCRIPITONS ARE COMPLETED BY ALL RATIO(S) AND TWO STEPS INTO ACCUMLATES A SERIES OF (BIO-TECHNOLOGY )AND DEVELOPED ASSUMPTIONS ARE DESCRIPTIONS INTO THE DECREASED ANALYSIS AND SERIES ARE COMPLETED COMMON ISSUES QUESTIONS:THE NEW TERMS OF SCIENTIFIC REPLACEMENTS ARE DEVELOPED INTO THESE QUESTIONS THAT DESCRIPTIONS ARE DUE THESE ASSUMPTIONS: THE FOLLOWING INTO THESE COLLECTIONS ARE DESCRIPTIONS INTO THESE QUESTIONS ACCOMPLISHES AND SERIES ARE COMBINATIONS WERENOT BUT ONLY ISSUES