Integrated Thin-film Lithium Niobate Devices and Circuits for Nonlinear- and Quantum-optic Applications

Implementation of high-performance photonic integrated devices and circuits is becoming a growing essential need for a plethora of classical and nonclassical applications such as, high-speed telecom and data-com systems, frequency metrology and quantum communication systems. These applications require a combination of linear optics (e.g., beam splitters and filters), fast modulation (e.g., electro-optic modulators) along with nonlinear optical processes. Thin-film lithium niobate (TFLN) stands as an ideal platform for that purpose due to its high electro-optic, nonlinear-optic, and ferroelectric effects, its wide transparency window, and its compatibility with fabrication technologies, especially, standard silicon photonics. This work aims at harnessing the unique properties of TFLN for implementation of high-performance integrated devices and circuits for nonlinear- and quantum-optic applications. First, we demonstrate thin-film periodically-poled lithium niobate (TF-PPLN) waveguides with the highest reported nonlinear conversion efficiency on TFLN to date. Then, we introduce a new class of wideband nonmagnetic and linear optical isolators, based on nonlinear frequency conversion and spectral filtering. We utilize TF-PPLN devices to experimentally demonstrate our novel isolator system with a wide bandwidth and high optical isolation ratio. We introduce and demonstrate efficient quantum-correlated photon-pair sources via nonlinearities in TF-PPLN waveguides. We also demonstrate tunable dual-channel ultra-narrowband Bragg grating filters on TFLN. All the demonstrated devices pave the path for implementation of high-performance advanced nonlinear and quantum photonic integrated circuits (PICs), as discussed in the future work directions