Guided Mode Resonance Enhanced Microscopy and Lasing

A major goal of nanophotonics research is to enhance light-matter interaction and to develop novel functionalities. The work in this thesis addresses this goal in 2 areas, i.e. microscopy and laser emission, using guided mode resonances (GMRs) as a tool. GMRs exhibit significant field enhancements, which makes them interesting for the enhancement of light-matter interactions, such as light scattering or fluorescence emission; the challenge was to show whether and how GMRs could be used to improve microscopy methods such as interferometric scattering microscopy (iSCAT) and fluorescence microscopy. The second challenge was to show whether GMRs could be used to enhance laser operation of 2D-material lasers. In the first part of the thesis, I describe how I built, tested and optimised an optical system that allows the study of enhanced microscopy. Then I demonstrate an efficient method for quantifying the enhancement of fluorescence excitation with a chirped GMR grating. With regular iSCAT, I was able to detect gold nanoparticles as small as 20 nm. In the second part, I show how a two-dimensional GMR grating can be used to both enhance the pump absorption and the laser emission of a WS2 monolayer. The devices, lasing with a low pump threshold, have a much higher output power and spatial coherence than other 2D-material lasers reported in the literature. The contrast enhancement in microscopy opens new possibilities, as it can either push the detection limits or simplify the setup requirements for detecting a given particle. Regarding the lasing application, I showed that the concept of GMR-based lasers with large area 2D-material gain media is promising. The concept could be adapted to other 2D-materials emitting at wavelengths relevant for communication or sensing applications. This would represent an important step towards operation with reduced power consumption or for opening novel opportunities for making lasers.