TY - JOUR

T1 - Boosting shortwave IR transmission in nonlinear crystals via UV-laser-produced anti-reflective microstructures

AU - Syubaev, Sergey

AU - Gurbatov, Stanislav

AU - Dostovalov, Alexandr

AU - Lobanov, Sergei

AU - Yelisseyev, Alexander

AU - Isaenko, Lyudmila

AU - Kuchmizhak, Aleksandr

N1 - The work is supported by the Russian Science Foundation, Russia (grant no. 25-79-20014).

PY - 2026/8/15

Y1 - 2026/8/15

N2 - Nonlinear infrared (IR) crystals for frequency conversion are essential part of advanced parametric devices used in medical diagnostics, environmental monitoring, and sensing. However, conversion efficiency in crystals is often limited by substantial surface reflectivity coming from the high refractive index of these materials in their transparency range. Here, using a Bridgman-grown LiInS2 as a model nonlinear crystal with a wide transparency window (0.42–12μm), we explored two complementary UV-laser-based pathways aiming at fabrication of sub-micron-scale anti-reflective microstructures (ARMs) on the input crystal facets, increasing shortwave IR transmittance (1.2–4μm) from 75% to 86%. The demonstrated ARMs include: (i) regular fish-net patterns with a period down to 500 nm directly produced by tightly focused laser beam scanning, (ii) self-organized nanogratings with the periods of 200 nm formed under loose focusing conditions, and (iii) hybrid structures combining both structure types. Our results highlight the underexplored UV femtosecond-laser nanotexturing as a promising and highly precise technique for direct liquid-free nanotexturing of nonlinear crystals towards their improved near-IR pump and frequency conversion performance.

AB - Nonlinear infrared (IR) crystals for frequency conversion are essential part of advanced parametric devices used in medical diagnostics, environmental monitoring, and sensing. However, conversion efficiency in crystals is often limited by substantial surface reflectivity coming from the high refractive index of these materials in their transparency range. Here, using a Bridgman-grown LiInS2 as a model nonlinear crystal with a wide transparency window (0.42–12μm), we explored two complementary UV-laser-based pathways aiming at fabrication of sub-micron-scale anti-reflective microstructures (ARMs) on the input crystal facets, increasing shortwave IR transmittance (1.2–4μm) from 75% to 86%. The demonstrated ARMs include: (i) regular fish-net patterns with a period down to 500 nm directly produced by tightly focused laser beam scanning, (ii) self-organized nanogratings with the periods of 200 nm formed under loose focusing conditions, and (iii) hybrid structures combining both structure types. Our results highlight the underexplored UV femtosecond-laser nanotexturing as a promising and highly precise technique for direct liquid-free nanotexturing of nonlinear crystals towards their improved near-IR pump and frequency conversion performance.

KW - Anti-reflective microstructures

KW - Laser processing

KW - Laser-induced periodic surface structures

KW - LiInS2 nonlinear crystals

KW - UV laser pulses

UR - https://www.scopus.com/pages/publications/105042521333

UR - https://www.mendeley.com/catalogue/6748bdca-1f94-3b42-ae36-9528285926c9/

U2 - 10.1016/j.surfin.2026.109899

DO - 10.1016/j.surfin.2026.109899

M3 - Article

VL - 95

JO - Surfaces and Interfaces

JF - Surfaces and Interfaces

SN - 2468-0230

M1 - 109899

ER -