Single-molecule studies allow the observation of heterogeneity between individual molecules that may be blurred in bulk measurements. Although fluorescent single-molecule measurements are common, they are limited in the analyte that can be observed. Absorption measurements are much more broadly applicable. Using optical resonators, it has previously been shown that photothermal spectroscopy can be performed on single particles. In this presentation, I will describe my work on the design and fabrication of multiple types of optical micro-cavities. I will focus on my work on designing and fabricating a new photothermal absorption spectroscopy platform based on microring resonators. Microring resonators promise increased sensitivity to reach smaller molecules.