When high intensities of light are focused inside of a medium, strange effects occur. Light can self-interact. It can be slowed down based on how bright it is, it can be made to go in one direction but not the other, and it can even be made to c change colour.
It is hard to imagine how the world would look if these were effects that we experienced in our everyday lives. Fortunately, it takes a significant amount of effort to make the conditions right for such events to occur, specifically, with high optical intensities required. This thesis details some of these efforts.
In this work, I present some applications of Kerr microresonantor based nonlinear and quantum optics. Microresonators are minute devices that can be integrated in photonic circuits. They trap and guide light on a repeating path, with each roundtrip leading to an increase in intensity until nonlinear effects start to occur.
I start by explaining how such resonators work, are fabricated, and how nonlinear effects can manifest. Next, an all-optical polarisation controller is introduced, in which the nonlinear splitting of otherwise degenerate polarisation modes is employed. This device could find application in integrated photonic circuits that require fast response times. A similar effect, but this time for counter-propagating light, is then used to demonstrate an all-optical, universal logic gate. Interestingly, a set of such logic gates could be used for the on-chip routing of optical signals to provide low-latency communications for telecoms and distributed computing. Finally, the quantum nature of these nonlinearities is explored, first with the calculation of multi-modal entanglement metrics before then discussing work that is progressing towards a single-photon source. These phenomena show promise for integration into future quantum technologies, in particular in secure quantum communications and for state generation for quantum information processing.