Overview of Methods Used
Building the WGM Resonator
Making a silicon dioxide WGM resonator chip is a lengthy process that takes 24 hours to complete. It can be broken down into three major parts; the addition of the resonator to the silicon dioxide chip, the xenon difluoride overnight etching, and the carbon dioxide cleaning
Measuring the Q Factor in Air
- A fiber taper is used as the medium to transfer a 660 nm laser to the edge of the resonator.
- Once the fiber makes contact with the rim of the resonator the resonator will begin the energy storing process and the Q factor can be measured using a computer program developed by a former graduate student. This can be seen in the video below.
Creating the PAA Hydrogel
- The process of creating a hydrogel solution is fairly simple and takes about 30 minutes
- The chemicals used are Poly(ethylene glycol) diacrylate (PEG), Acrylic Acid (AA), and 2,2-Dimethoxy-2-phenylacetophenone
- PEG is a chemical with a low viscosity that acts as the base for our hydrogel
- AA is the pH-sensitive chemical that showcases the novelty of the experiment
- 2,2-Dimethoxy-2-phenylacetophenone, otherwise known as photoinitiator, is a powdery substance that allows for the hydrogel solution to cure under the UV light
- The ratio is 95:5 PEG:AA with the addition of 10% of the molecular weight of the ratio in photoinitiator and then the solution is diluted to 90:10 water:hydrogel