@article{10902/38297,
year = {2025},
month = {10},
url = {https://hdl.handle.net/10902/38297},
abstract = {Gallium sulphide (GaS) is an emerging monochalcogenide material that has recently attracted interest in optical technologies due to its tunable bandgap in the near-UV region. In this work, we employ in situ, in-operando X-ray diffraction to investigate local atomic modifications in GaS induced by 400-nm femtosecond laser pulses. We identify the energy threshold at which irreversible structural changes occur and observe a laser-induced elongation of the unit cell along the c-axis. This elongation is expected to enhance the anisotropy of the material's physical properties. Ab initio calculations further reveal that the experimentally observed ≈ 10% elongation along the c-axis leads to a transition from a direct to an indirect bandgap, accompanied by a bandgap increase of approximately 0.45 eV. Additional ab-initio optical simulations show that this structural transformation results in a nearly constant in-plane refractive index contrast of Dn ≈ 0.1 across a wide spectral range, from the visible to the near-infrared, with negligible optical losses, which could be of interest for reconfigurable photonics applications.},
organization = {ELI ERIC; ADONIS (CZ.02.1.01/0.0/0.0/16 019/0000789); European Union’s Horizon 2020 Research and Innovation Program (899598-PHEMTRONICS,871124); Ramon y Cajal Fellowship (RYC2022-037828-I); HEU-GA (101131771); European Commission (101094299 (IMPRESS)).},
publisher = {Optica Publishing Group},
publisher = {Optical Materials Express, 2025, 15(10), 2534-2544},
title = {Engineering GaS crystal anisotropy via ultrafast laser excitation},
author = {Khakurel, Krishna P. and Clady, Raphael and Espinoza, Shirly and Chaulagain, Uddhab and Ferre, Amelie and Andreasson, Jakob and Lusordo, Maria and Juan, Dilson and Uteza, Olivier and Gutiérrez Vela, Yael},
}