NEAR FIELD EFFECT OF LIGHT INTERACTION WITH TRANSPARENT MICROSPHERES

UoM administered thesis: Phd

  • Authors:
  • Ashfaq Khan

Abstract

With the increasing demand for miniaturized devices there is a need for economic and reliable nano fabrication and nanoscopy techniques. This Thesis aims to improve the laser micro/nano patterning by contact particle lens array (CPLA) technique and also extend the CPLA technique to white light nanoscopy. CPLA has been used for patterning for nearly a decade. They have been used to fabricate bumps, bowls and user defined features on the surface of material. However, the CPLA method is limited to patterning of flat, smooth and hydrophilic substrates. Moreover, the particles can only be deposited once and are not recoverable. Thus the particles could not be used repeatedly.The thesis was aimed at transporting a monolayer to pattern curved, rough or hydrophobic surfaces. A Particle monolayer was formed on a smooth, flat and hydrophilic surface. The transportation of the particle monolayer was carried out by a flexible transparent (to the processing laser) sticky surface. The monolayer was adhered to the plastic and then peeled off and wrapped on the new surface. Laser processing was carried out by the laser passing through the sticky surface. The sticky surface and the adherent particles were peeled off and reused. The effect of the laser processing parameters (scan speed, power and fluence) was experimentally investigated. An understanding of the process was developed by numerical and analytical simulation. Analytical simulation was carried out by Mie and particle on surface (POS) theory which provided the near field distribution for a single particle. Detailed simulation, modelling the presence of resin, was conducted by finite integration technique (FIT). Coupled electromagnetic and thermal modelling was conducted to understand temporal temperature distribution in the near field.The Thesis also investigated the utilization of CPLA for extending the capability of a white light microscopy to nanoscopy. Nano scales features on a substrate were imaged by a standard white light microscope by observing through a CPLA deposited on its surface.The novelty of the work is that it uses a simple method to transport large area monolayer arrays of about 100 mm2 and utilize it for repeated (up to three times) patterning of substrates that were previously considered impossible to be patterned. The thesis also presents a novel method of nanoscopy by using CPLA.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
  • Lin Li (Supervisor)
  • Mohammad Sheikh (Supervisor)
  • Zengbo Wang (Supervisor)
Award date31 Dec 2011