The main objective of the ERC Starting Grant "CounterLight" was the investigation of interaction of counterpropagating light in integrated photonic circuits and optical ring resonators. Our diverse work on this topic has led to more than 30 scientific publications. The following is a list of the most important outcomes related to each of the proposed work packages.
WP1: In work package 1 we investigated optical gyroscopes that are enhanced by the nonlinear interaction of counterpropagating light in microresonators. In this work, we build an optical gyroscope based on a whispering gallery microresonator, demonstrate the physical principle for the first time and test its performance. This work has led to the publication “Nonlinear Enhanced Microresonator Gyroscope”, Optica 8, 1219-1226.
WP2: In this work package we investigate the use of nonlinear interaction of counterpropagating light to build an optical diode, which is a device that supports light propagation in one direction, while blocking backwards propagating light. This work has led to the publication “Microresonator Isolators and Circulators Based on the Intrinsic Nonreciprocity of the Kerr Effect”, Optica 5, Issue 3, pp. 279-282.
WP3: Here, we investigated the use of clockwise and counterclockwise circulating light states in ring resonators to store and process data in photonic circuits. We investigate the switching times between light states and in separate work we build an all-optical logic gate for simple optical calculations. This technique can be used to build future optical computers, e.g. for AI applications and for neuromorphic computing. This has led to the publication “Logic Gates Based on Interaction of Counterpropagating Light in Microresonators”, J. Lightwave Technol. 38, 1414-1419 as well as the publication “Optical memories and switching dynamics of counterpropagating light states in microresonators”, Opt. Express 29, 2193-2203.
WP4: We investigated the use of counterpropagating light for optical sensors and near-field sensing. In our experiments we employed a Tungsten tip in order to control the optical fields in counterpropagating modes of a microresonator. In particular, this can be used to suppress back reflection of light in optical circuits, which is important in optical networks, gyroscopes and other precise optical sensors. This work has been published as “Coherent suppression of backscattering in optical microresonators”, Nature, Light Science and Applications 9, 204.
WP5: Here, we investigated different types of optical frequency combs in optical microresonators. Frequency combs are optical signals that consist of many colors, that are equidistantly spaced in optical frequencies. Similar to a ruler with equidistant marks to measure distances, an optical frequency comb can be used to measure optical frequencies with very high precision. This has led to the following publications: “Spectral Extension and Synchronisation of Microcombs in a Single Microresonator”, Nature Comms. 11, 6384, “Dark-Bright Soliton Bound States in a Microresonator”, Phys. Rev. Lett. 128, 033901, and “Low-Temperature Sputtered Ultralow-Loss Silicon Nitride for Hybrid Photonic Integration”, Laser & Photonics Reviews, 2300642.
In addition to the work mentioned above, we have published a large number of additional theoretical and experimental work based on the nonlinear interaction of light.
