OP Collaborative Research: Taking lithium-niobate to the nanoscale: shaping revolutionary material onto photonic microchips for developing next-generation light sources

Stanford University, Stanford CA

Investigators

Abstract

Abstract title: OP Collaborative Research: Taking lithium-niobate to the nanoscale: shaping revolutionary material onto photonic microchips for developing next-generation light sources Abstract (general): Lithium-niobate is a revolutionary material that has played a major role in transforming optical telecommunications. It has enabled electronic data (0s and 1s) to be directly written onto light pulses that travel the globe and essentially form the backbone of the internet. It is also used to change the color of light emitted by lasers, of importance for high-speed computing and sensing, as well as to enable realization of novel quantum sources of light that may enable next-generation ultra-secure optical communications. However, currently the performance of lithium-niobate based optical devices is limited by their bulky size. This project aims to miniaturize these to the nanoscale by patterning lithium-niobate onto a photonic microchip, thereby enhancing their efficiency many-fold. This will enable the design of novel light sources with greatly improved properties compared to current technology and also significantly reduce the optical power requirements. The proposed research program is a natural template for informing students, teachers, and the public of how scientists and engineers explore the unique behavior of materials at the nanoscale, and make use of these properties in the creation of new devices. The team will leverage the "magic" of optics and lasers to engage a wide audience and inform the public of their ongoing research. The program has strong theoretical and experimental components and addresses both fundamental and engineering aspects of light-generation in nanoscale optical devices and systems. Therefore, it represents a unique research and educational opportunity for students at all levels. The devices and systems that will be developed will be of great interest to both the scientific community and commercial industry. Abstract (technical): Lithium-niobate, with its large second-order susceptibility, relatively large refractive index and wide transmission window extending from ultra-violet to mid-infrared, is one of the most important optoelectronic materials, widely used for electro-optic modulation and classical & quantum optical frequency conversion. However, due to difficulties associated with fabrication, most of these components are discrete and cannot be easily integrated onto a photonic microchip. Fortunately, recent advances in lithium-niobate thin-film fabrication techniques, via crystal ion slicing, are promising and enable chip-scale integration of nanophotonic devices. The proposed program builds on these results and seeks to develop an integrated nonlinear nanophotonics platform that combines the unique material properties of periodically-poled lithium-niobate with the superior light confinement and dispersion engineering in wavelength-scale optical waveguides and cavities. The new platform will be developed based on thin x-cut lithium-niobate device layers (~500-nm thick) bonded on top of a SiO2 substrate that provides optical isolation. The team will develop new techniques for surface poling of thin x-cut lithium-niobate films, thus allowing for efficient phase matching. State of the art nanofabrication techniques will be used to realize optical waveguides and cavities directly in the periodically-poled device layer. The devices will operate over a wide wavelength range (visible to mid-infrared) and enable strong photon interactions resulting in 40-fold more efficient nonlinear processes than those found in conventional counterparts. The program is expected to result in a wide variety of integrated devices and systems with applications in quantum frequency conversion, entangled-photon pair generation, supercontinuum generation, and frequency comb generation. The proposed program is transformative since it introduces lithium-niobate into the family of materials suitable for integrated, on-chip photonics. It will result in the development of a wide range of novel & more efficient nonlinear optical devices & systems, and make an impact on disciplines as diverse as quantum information science & technology, remote sensing, astronomy and optoelectronics.