Integrated optics in silicon carbide
Dr Alberto Politi, University of Southampton, UK
The excellent physical properties of silicon carbide offer a wide range of potential applications for optics, from photonic devices spanning a wide wavelength range to non-linear and quantum optics. This talk will discuss the recent advances on the integration of optical components in silicon carbide, particularly focusing on the 3C polytype. A complete photonic platform that includes grating couplers, waveguides and ring resonators has been developed, offering a platform for classical and non-linear optics. The demonstration of photonic crystal cavities that show high field confinement will be presented. Their integration with colour centres can expand applications to the quantum technology domain. Finally, the extension to longer wavelength ranges will be discussed. Sub-wavelength confined cavities and strong nonlinearities can be achieved in the mid-infrared band by harnessing the unique phononic properties of SiC.
Optimizing Spin and Optical Defect Signatures in SiC Nanocavities
Professor Evelyn Hu, Harvard University, USA
Various polytypes of SiC have demonstrated spin-active point defects with substantial coherent times at room temperature. A single defect, such as the silicon vacancy (SiV) in 4H SiC, occupying different lattice sites (hexagonal or cubic) will produce different zero-phonon-line (ZPL) emission wavelengths. Thus, there is a richness of information about these defects relating details of the local atomic environment, such as strain, to the spin- and photon-dependent performance of the defects. High quality SiC nanocavities, designed and fabricated to match the embedded defects, not only enhance the optical emission of these defects, but also serve as “nanoscopes” that can elucidate details of the defects’ atomic environment. This talk will illustrate the application of nanobeam photonic crystal cavities, fabricated from 4H-SiC, to achieve an 80-fold optical enhancement of a Si-vacancy transition with emission at about 860 nanometers. The cavities can also highlight details of defect motion at elevated temperatures and suggest avenues of better placement of defects within the cavities.
Silicon carbide color center photonics
Dr Marina Radulaski, Stanford University, USA
Silicon carbide color centers are promising systems for quantum communication, spintronics and sensing. Their integration with photonic devices is a path to scalability, higher efficiency and new regimes of operation. Advanced material processing is the main challenge in the realization of the designed devices. So far, high quality color centers have been available only in bulk substrates, which impedes the development of freestanding nanophotonic structures, such as photonic crystal cavities. This talk will report on the progress in the development of nanofabrication processes in bulk silicon carbide, and hybrid silicon carbide-diamond platform, where color centers are hosted in nanodiamonds. The realized systems provide a scalable interface for addressing individual SiC color centers and demonstrate SiC-assisted Purcell enhancement of diamond color center emission.
Furthermore, theoretical insights into cavity quantum electrodynamics of color centers will be discussed. The small inhomogeneous broadening of color center ensembles is leveraged to potentially achieve collective coupling to a common cavity. Such regime not only exhibits arbitrarily high light-matter interaction, but also holds novel quantum light generating mechanisms. In addition to the conventional photon blockade that results in a steam of individual photons, multi-emitter-cavity systems can facilitate the so-called subradiant photon blockade with higher purity of single-photons. Finally, they also offer three-photon generating channels.
High-performance microcavity arrays for solid-state qubits
Dr Michael Trupke, University of Vienna, Austria
Numerous applications in quantum technology, including photon generation, nanoparticle manipulation, and optical readout of qubits, require enhanced interactions between light and matter. Such an enhancement can be achieved with the use of microcavities, in which strong spatial confinement and high-reflectivity mirrors can drastically increase the desired interaction strength. For several of the intended applications, such as quantum computation and communication, it will furthermore be beneficial to create large numbers of efficient light-matter interfaces.
In this presentation, results from the University of Vienna in creating high-performance microcavity arrays will be discussed. The microcavities are micro-machined using highly precise lithographic methods, which enable the creation of large arrays of devices. By tailored optimization of the mirror morphology and surface quality, these microcavities have now reached a mirror reflectivity which approaches that of the best available macroscopic substrates. Lithographically defined alignment structures were furthermore used to robustly align arrays of micromirrors to each other while preserving their high performance values. As each microcavity needs to resonant with the desired optical transition, tuning of the microcavities using integrated micro-electromechanical actuators will also be described. Finally, efforts towards the integration of optically active defects in diamond and silicon carbide will be presented.