Issue 15, 2018

Laser inscription of pseudorandom structures for microphotonic diffuser applications

Abstract

Optical diffusers provide a solution for a variety of applications requiring a Gaussian intensity distribution including imaging systems, biomedical optics, and aerospace. Advances in laser ablation processes have allowed the rapid production of efficient optical diffusers. Here, we demonstrate a novel technique to fabricate high-quality glass optical diffusers with cost-efficiency using a continuous CO2 laser. Surface relief pseudorandom microstructures were patterned on both sides of the glass substrates. A numerical simulation of the temperature distribution showed that the CO2 laser drills a 137 μm hole in the glass for every 2 ms of processing time. FFT simulation was utilized to design predictable optical diffusers. The pseudorandom microstructures were characterized by optical microscopy, Raman spectroscopy, and angle-resolved spectroscopy to assess their chemical properties, optical scattering, transmittance, and polarization response. Increasing laser exposure and the number of diffusing surfaces enhanced the diffusion and homogenized the incident light. The recorded speckle pattern showed high contrast with sharp bright spot free diffusion in the far field view range (250 mm). A model of glass surface peeling was also developed to prevent its occurrence during the fabrication process. The demonstrated method provides an economical approach in fabricating optical glass diffusers in a controlled and predictable manner. The produced optical diffusers have application in fibre optics, LED systems, and spotlights.

Graphical abstract: Laser inscription of pseudorandom structures for microphotonic diffuser applications

Supplementary files

Article information

Article type
Paper
Submitted
19 Jan 2018
Accepted
10 Mar 2018
First published
14 Mar 2018
This article is Open Access
Creative Commons BY license

Nanoscale, 2018,10, 7095-7107

Laser inscription of pseudorandom structures for microphotonic diffuser applications

T. Alqurashi, A. Alhosani, M. Dauleh, A. K. Yetisen and H. Butt, Nanoscale, 2018, 10, 7095 DOI: 10.1039/C8NR00529J

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