Laser inscription of pseudorandom structures for microphotonic diffuser applications

Area of Science:

• Materials Science
• Optical Engineering
• Laser Processing

Background:

• Optical diffusers are crucial for applications needing Gaussian intensity distribution, such as imaging and biomedical optics.
• Laser ablation offers rapid fabrication of efficient optical diffusers.

Purpose of the Study:

• To demonstrate a novel, cost-efficient method for fabricating high-quality glass optical diffusers using a continuous CO2 laser.
• To investigate the characteristics and performance of diffusers produced by this technique.

Main Methods:

• Fabrication of surface relief pseudorandom microstructures on glass substrates using a continuous CO2 laser.
• Numerical simulation of temperature distribution and FFT simulation for diffuser design.
• Characterization using optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy.

Main Results:

• CO2 laser processing created microstructures with predictable hole dimensions (137 μm per 2 ms).
• Increased laser exposure and diffusing surfaces improved light diffusion and homogenization.
• Produced diffusers exhibited high-contrast speckle patterns with bright spot-free diffusion.

Conclusions:

• The demonstrated CO2 laser method provides an economical and predictable approach for fabricating optical glass diffusers.
• The technique prevents glass surface peeling and yields diffusers suitable for fiber optics, LED systems, and spotlights.