研究目的
Investigating the fabrication of volume-phase gratings (VPGs) inside Ge–As–S chalcogenide glasses (ChG) with femtosecond-laser writing technology and analyzing their optical performance.
研究成果
VPGs with high thicknesses and diffraction efficiencies were successfully fabricated inside Ge–As–S chalcogenide glasses using femtosecond-laser writing technology. The maximum diffraction efficiency reached 50% at 808 nm under optimized laser parameters. The study demonstrates the potential of femtosecond laser writing in the preparation of photonic devices in highly nonlinear ChGs.
研究不足
The study is limited by the laser damage threshold of the glass, which affects the maximum achievable grating thickness and diffraction efficiency. Surface damage at higher pulse energies also impacts the uniformity and performance of the gratings.
1：Experimental Design and Method Selection
Utilized femtosecond-laser direct writing technology to fabricate VPGs inside Ge–As–S chalcogenide glasses, exploiting the self-focusing effect of highly nonlinear ChGs.
2：Sample Selection and Data Sources
Ge–As–S glass samples were prepared via standard melt quenching techniques, cut into 1 mm-thick discs, and polished for the experiment.
3：List of Experimental Equipment and Materials
Ti:sapphire femtosecond laser (Mira 900D, Coherent), optical parametric amplifier system (Legend Elite+, Coherent), 50× objective lens, 3D mobile platform, power meter, CCD camera, ultraviolet–visible near-infrared spectrophotometer (Perkin Elmer Lambda 950), Fourier transform infrared spectrophotometer (Nicolet 380), IR variable-angle spectroscopic ellipsometer (Mark II, J. A. Woollam), high-resolution microscope (VHX-1000E, Keyence).
4：Experimental Procedures and Operational Workflow
The laser was focused inside the glass sample, and VPGs were fabricated with different laser pulse energies. The diffraction efficiency and patterns were measured using lasers at 808 nm and 1550 nm.
5：Data Analysis Methods
Diffraction efficiency was calculated based on the measured intensity of diffracted light. Grating thickness and refractive index changes were analyzed using microscopy and theoretical models.
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