Surface transmission enhancement of ZnS via continuous-wave laser microstructuring

Kevin J. Major; Catalin M. Florea; Menelaos K. Poutous; Lynda E. Busse; Jasbinder S. Sanghera; Ishwar D. Aggarwal

doi:10.1117/12.2036790

6 March 2014 Surface transmission enhancement of ZnS via continuous-wave laser microstructuring

Kevin J. Major, Catalin M. Florea, Menelaos K. Poutous, Lynda E. Busse, Jasbinder S. Sanghera, Ishwar D. Aggarwal

Proceedings Volume 8968, Laser-based Micro- and Nanoprocessing VIII; 896810 (2014) https://doi.org/10.1117/12.2036790
Event: SPIE LASE, 2014, San Francisco, California, United States

Abstract

Fresnel reflectivity at dielectric boundaries between optical components, lenses, and windows is a major issue for the optics community. The most common method to reduce the index mismatch and subsequent surface reflection is to apply a thin film or films of intermediate indices to the optical materials. More recently, surface texturing or roughening has been shown to approximate a stepwise refractive index thin-film structure, with a gradient index of refraction transition from the bulk material to the surrounding medium. Short-pulse laser ablation is a recently-utilized method to produce such random anti-reflective structured surfaces (rARSS). Typically, high-energy femtosecond pulsed lasers are focused on the surface of the desired optical material to produce periodic or quasi-periodic assemblies of nanostructures which provide reduced surface reflection. This technique is being explored to generate a variety of structures across multiple optical materials. However, femtosecond laser systems are relatively expensive and more difficult to maintain. We present here a low power and low-cost alternative to femtosecond laser ablation, demonstrating random antireflective structures on the surface of Cleartran ZnS windows produced with a continuous-wave laser. In particular, we find that irradiation with a low-powered (<10 mW), defocused, CW 325nm-wavelength laser produces a random surface with significant roughness on ZnS substrates. The transmission through the structured ZnS windows is shown to increase by up to 9% across a broad wavelength range from the visible to the near-infrared.

Citation Download Citation

Kevin J. Major, Catalin M. Florea, Menelaos K. Poutous, Lynda E. Busse, Jasbinder S. Sanghera, and Ishwar D. Aggarwal "Surface transmission enhancement of ZnS via continuous-wave laser microstructuring", Proc. SPIE 8968, Laser-based Micro- and Nanoprocessing VIII, 896810 (6 March 2014); https://doi.org/10.1117/12.2036790

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