Seeing is believing. Being able to see is crucial for understanding our environment. Light is detected by our eyes and converted into electric signals. These signals travel to the brain, where this information is interpreted as color and shapes. This is just one example of the interaction between light and matter. In general, light-matter interactions take place on all different length-scales from whole planets down to a single atom. The strength of a light-matter interaction can have a dramatical impact on the optical as well as material related properties of the interacting system. For instance, gold in a bulk form has a specific yellowish shiny color. However, a tiny gold particle at the nanoscale can appear in red, blue, green, or any other color over the whole visible spectrum of light, depending on the size and shape of the particle, and the refractive index of its surrounding medium. The reason for this is a strong light-matter interaction, called plasmon polariton. This results in a huge modification of the particles optical properties, such as which color of light is reflected and which is absorbed. One of the earliest examples of such a plasmonic effect is the 4th century Roman Lycurgus cup. The color of the cup depends on if a light-source is in front or behind the cup. In reflection the cup appears to be green, while looking at light transmitted through the cup it appears to be red.
In modern science, strong light-matter interactions or strong coupling, is very attractive due to its ability to merge different fields of physics, namely quantum optics and material science. Furthermore, many interesting effects in quantum physics require cooling to temperatures below -200 degree Celsius, whereas strong coupling could make them accessible at ambient conditions.
This thesis aims to contribute in a better understanding of single plasmonic nanoparticle strong coupling with excitonic materials at ambient conditions.