Surface structuring of glass with submicrometer features using selective laser etching.

Area of Science:

• Materials Science
• Optics and Photonics
• Microfabrication

Background:

• Selective laser etching (SLE) is a key technique for fabricating micro-fluidic and micro-mechanical structures in glass.
• Current applications of SLE are primarily in micro-fluidics and micro-mechanics, with limited exploration in optics production.
• Achieving optical-quality surfaces directly via SLE is challenging due to surface roughness limitations.

Purpose of the Study:

• To investigate the optimization of Selective Laser Etching (SLE) parameters for producing optical-quality surfaces in glass.
• To determine the feasibility of using SLE for direct fabrication of optical components and integrated optical structures.
• To achieve a surface roughness suitable for visible wavelength applications without post-processing.

Main Methods:

• Systematic variation of SLE parameters including stage speed, laser power, polarization, and repetition rate.
• Characterization of surface roughness using profilometry or atomic force microscopy.
• Fabrication of micro-structures in fused silica using SLE and potassium hydroxide (KOH) etching.

Main Results:

• A surface roughness of approximately 30 nm was achieved by optimizing SLE parameters.
• This surface roughness is sufficient for fabricating optical components and integrated optical structures for the visible wavelength range.
• Free-standing micro-structures with feature sizes below 1 µm were successfully fabricated.

Conclusions:

• Selective laser etching (SLE) can be optimized to produce optical-quality surfaces in glass, eliminating the need for additional polishing steps.
• The optimized SLE process enables the direct fabrication of micro-optical components and integrated optical structures for visible light applications.
• This advancement facilitates the production of precise micro-structures, such as optical gratings, in fused silica.