Holographic laser ablation for nanopatterning

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Alqattan, Bader Ahmad (2019). Holographic laser ablation for nanopatterning. University of Birmingham. Ph.D.

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Abstract

Current lithography methods to produce nanophotonic devices for optical applications are costly and time consuming. Holographic direct laser interference patterning has helped to establish a strategy to rapidly create 1/2D nanopatterns from a variety of materials. A 640 nm × 640 nm pattern structure of Au-Ti was accomplished by controlling the distances between the laser source, the recording medium, and the object. This metal structure has a limitation in regard to thickness to develop better and efficient light diffraction intensity. Later, the Denisyuk reflection mode method was used on the films (about 1 µm) of four ink-based dye colours (black, red, blue, and brown) to fabricate low-cost and efficient nanopatterns. The dyes have the same structural nano spacing (840 nm), but they produced different diffraction in response to monochromatic and broadband light. The recording mediums have different light absorption ranges and the black has the highest absorption. After that, we focused on contact lenses which are universal low-cost biomedical devices with possible applications as quantitative analytical devices for point-of-care diagnostics. Incorporating nanoscale features into commercial contact lenses as low-cost biosensors is considered a challenge. As the black dye has a high optical absorption, it was deposited over a contact lens to produce optical nanostructures on the surface, via holographic laser ablation for sensing ocular diseases. The holographic nanostructures showed a great response to sensing a change of Na+ ions (±47 mmol L-1) in a human tear, to diagnose the severity of a dry eye condition at the early stages. Likewise, this advantage of the black dye’s absorption can be used to produce economical optical strain sensors for civil engineering, aerospace and human interface applications. A holographic interference patterning mode was used to produce nanostructures on a commercial adhesive tape to fabricate a surface compatible, lightweight and cost effective strain sensor for rapid response to cracks, deflections or tears of 5 µɛ.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):