Absorption enhancement in evanescently-coupled waveguides

In this project the main goal is to construct various thin films of different thicknesses of CYTOP and PMMA in a glass substrate using the spin coating. A glass, CYTOP and PMMA was proposed. Although this substrate was bio-imaging oriented in order to enhance resolutions and get better signals when working with bio-samples, is also a good platform for luminescence cooling. In a MatLab simulation, we find that the best thicknesses that will enhance the electrical field on the films surface at a resonant angle between 65-70 degrees are ~600-750 nm and ~350-450 nm, respectively. Then, Glass/CYTOP/PMMA substrate were successfully spin-coated with an optimal thickness achieved between ~700nm (for CYTOP) and ~400nm (for 1wt% of Lumogen Red L305 with PMMA). Photoluminescence (PL) spectra was enhanced and absorption is stronger on thicker films. The reflectivity spectrum shows that the resonant angle was ~47 degrees. The idea of cooling a solid-state optical material by simply shinning a laser beam onto it, the advantages of compactness, the absence of vibrations and moving parts or fluids, high reliability and the ability to operate without cryogens is rapidly becoming a promising technology for future cryocoolers.