I. Background 🚀
This experiment focuses on the application of femtosecond laser technology in fabricating 3D microstructures inside glass. By precisely controlling laser parameters, material characteristics, and processing strategies, we explore various internal modification mechanisms of glass and assess their potential applications in photonic devices, microfluidic channels, and precision bonding.
Due to its high mechanical strength, optical transparency, and chemical stability, glass is widely used in optical components, microfluidic chips, and biomedical engineering. However, traditional glass processing methods are limited in terms of precision, structural complexity, and material damage, making them unsuitable for advanced micro/nano fabrication—especially for true 3D microstructures.
Femtosecond laser processing, characterized by ultrashort pulse duration and extremely high peak power, enables “cold processing” with minimal thermal effects, significantly reducing material damage and improving precision. Moreover, its nonlinear absorption effect allows direct internal modification of transparent glass without the need for masks or sacrificial layers, making it a promising tool for true 3D glass structuring.
• High-Density, High-Precision Metal Micropore Array Filters
II. Experimental Approach 🚀
We employed femtosecond laser direct writing to achieve precise internal modification in glass under different energy inputs and processing strategies. Depending on the interaction mechanism between the laser and material, three primary modes were utilized:
1. Refractive Index Modification
The laser energy is carefully tuned to induce localized refractive index changes without visible damage to the glass. This method is ideal for fabricating optical waveguides and integrated photonic components, enabling precise routing and manipulation of light signals within the glass substrate.
2. Nanograting Formation
Femtosecond laser pulses induce periodic nanostructures inside the glass, resulting in optical anisotropy at the microscale. This is useful for fabricating polarization-sensitive devices such as waveplates and diffraction gratings. By adjusting laser polarization and scanning strategies, the period and orientation of nanogratings can be precisely controlled to enhance device performance.
3. Volume Etching
High-energy femtosecond pulses generate micro-explosions inside the glass, creating nanoscale or microscale voids. Subsequent chemical etching (e.g., using HF or KOH solutions) selectively removes the modified regions, enabling the fabrication of complex 3D microfluidic structures. This method overcomes the limitations of conventional wet etching and achieves higher resolution and design freedom, making it suitable for microfluidic chips, biosensing platforms, and micromechanical systems.
We further investigated the effects of key parameters—such as pulse energy, repetition rate, and scanning speed—on the quality of the resulting microstructures. Various types of glass, including fused silica, borosilicate glass, and sapphire, were also tested for processing compatibility. The results demonstrate that optimized parameter control can significantly enhance structural precision, reduce thermal effects, and improve long-term stability.
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