The broadband dielectric architecture of layered gallium sulfide (GaS) for linear and nonlinear optical applications

Date

2026-06-01

Author

Mecit, Giray
Isik, Mehmet
Hasanlı, Nızamı

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Layered GaS is increasingly considered for ultraviolet optoelectronics, van der Waals nanophotonics, and nonlinear optical platforms; however, a self-consistent bulk dielectric reference connecting its dispersion, absorption, optical-conductivity, and energy-loss response remains limited. Here, we report the room-temperature effective pseudo-dielectric response of Bridgman-grown bulk GaS single crystals determined by spectroscopic ellipsometry over the photon-energy range 1.2-6.0 eV. From freshly cleaved (001) surfaces, the refractive index, extinction coefficient, absorption coefficient, optical conductivity, and surface/volume energy-loss functions are extracted within a unified framework. First-derivative analysis of the absorption coefficient identifies the indirect absorption onset at approximately 2.47 eV, consistent with previous optical benchmarks. In the transparent spectral region, the Wemple-DiDomenico single-effective-oscillator model yields E0 approximate to 6.01 eV, Ed approximate to 34.6 eV, and a static refractive index of n0 approximate to 2.60. Pronounced optical-conductivity features near 3.9 and 5.3 eV are discussed in relation to previously established interband critical-point transitions. In addition, order-of-magnitude third-order nonlinear optical parameters are estimated using Miller's generalized rule and are presented strictly as guides for nonlinear-experiment design. The resulting dataset provides an effective ordinary-channel bulk reference for modeling GaS-based UV photodetectors, reconfigurable phase-change photonic components, nonlinear optical elements, and high-refractive-index van der Waals nanophotonic structures.

URI

https://hdl.handle.net/11511/119547

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Department of Physics, Article