Realisation of a sub-wavelength dimple using a 193 nm wavelength photonic nano jet

Al-Jarwany, Q. A.; Mohammed, A. F.; Hamza, A. O.; Bouillard, J. S.G.; Adawi, A. M.; Pamme, N.; Walton, C. D.

Abstract

There are many areas of research that benefit from tight focussing of light. We report experimental and computational results of a laser irradiated silica microsphere, 1 μm diameter localised on an SU-8 substrate. A single pulse from an ArF excimer laser (λ = 193 nm) was used to generate a Photonic Nano Jet (PNJ). Subsequently the PNJ was used as a processing tool to produce a dimple cavity in the supporting SU-8 layer. Atomic Force Microscopy (AFM) was employed to determine dimple geometry. Measurements revealed a diameter of 150 ± 10 nm at full-width-half-maximum and a depth of 180 ± 10 nm. Finite Difference Time Domain (FDTD) simulations were carried out to visualise the propagation of 193 nm radiation through a microsphere. Experimental measurements and simulations were in close agreement confirming that the electromagnetic radiation is tightly focussed by the microsphere. Finite Element Method (FEM) simulations were also carried out to calculate the laser induced temperature rise of SU-8 in the region beneath the microsphere. FEM simulations predicted a temperature of 775 K which is above the boiling point of SU-8 (480 K). We briefly discuss the ejection mechanism of the microsphere in terms of the increase in temperature of the underlying SU-8.

Citation

Al-Jarwany, Q. A., Mohammed, A. F., Hamza, A. O., Bouillard, J. S., Adawi, A. M., Pamme, N., & Walton, C. D. (2020). Realisation of a sub-wavelength dimple using a 193 nm wavelength photonic nano jet. Chemical Physics Letters, 750, Article 137400. https://doi.org/10.1016/j.cplett.2020.137400

• Journal Article Type: Article
• Acceptance Date: Mar 21, 2020
• Online Publication Date: Apr 8, 2020
• Publication Date: 2020-07
• Deposit Date: Dec 8, 2020
• Publicly Available Date: Feb 1, 2023
• Journal: Chemical Physics Letters
• Print ISSN: 0009-2614
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 750
• Article Number: 137400
• DOI: https://doi.org/10.1016/j.cplett.2020.137400
• Keywords: Microsphere; Photonic nano-jet; Laser
• Public URL: https://hull-repository.worktribe.com/output/3495109