Anastasiia Zalogina

Developing chip-scale photonic platforms for the visible spectrum is essential for translating next-generation optical technologies. Here, we demonstrate that tantalum pentoxide Ta2O5 on insulator is a highly promising material framework for these applications, supporting high-Q resonator architectures across the visible spectral range. Utilizing routine and scalable thin-film deposition and fabrication methodologies, we realize Ta2O5 waveguide and resonator layouts compatible with photonic integrated circuit (PIC) architectures. Through a comparison with numerical simulations, we characterize compact racetrack resonators, evaluating their performance in both the green and blue spectral regions. In addition, we fabricate large-scale ring resonators exhibiting record-high quality factors for Ta2O5 in the visible spectrum, exceeding 7.0 × 104. These results highlight the immense potential of this platform for visible photonic systems and establish a robust, straightforward baseline for future visible integrated optics.

Single‐photon emitters in hexagonal boron nitride (hBN) combine bright optical emission with optically addressable spin states, offering a promising platform for integrated quantum photonics. However, their stochastic creation and spectral variability have prevented deterministic integration with photonic cavities. Here we demonstrate a fabrication protocol that enables precise, deterministic coupling of pre‐selected visible emitters to circular Bragg grating (CBG) cavities in hBN. By patterning etched alignment markers and performing pre‐fabrication confocal mapping, we locate emitters with sub‐micron accuracy and design cavity geometries matched to their zero‐phonon line wavelengths. The resulting devices show enhanced emission and reliable spectral alignment between emitter and cavity mode. This work establishes a deterministic cavity‐emitter integration scheme in a van der Waals material and provides a scalable route toward on‐chip quantum photonic and spin‐based platforms using hBN.

Recent progress in theoretical modeling, numerical simulation, and nanofabrication has established photonic moiré structures as a practical platform for engineering optical bands, localization, and radiation. Moiré photonics refers to optical systems in which a long-wavelength superstructure emerges from controlled mismatch between periodic elements, including relative rotation, lateral shift, or parameter detuning. In this paper, we focus on moiré photonic crystals, especially twisted-bilayer and merged photonic-crystal platforms, where relative twist, stacking, and interlayer coupling act as geometry-level control knobs that reshape optical minibands, momentum-conversion channels, the local density of states, and radiative leakage through band folding, hybridization, and interference. We summarize the construction of commensurate moiré superlattices, the physical mechanisms of moiré scattering and localization, and recent experimental progress in cavities, collective and chiral lasing, cavity quantum electrodynamics, and nonlinear frequency conversion and beam shaping. Throughout, we place moiré nanophotonics within the broader landscape of supercell photonics by comparing them with deterministic supercells, coupled-cavity arrays, and inverse-designed structures. We conclude by outlining the key challenges and opportunities related to scalability, disorder tolerance, leakage control, and real-time reconfigurability.

Light beams possessing orbital angular momentum (OAM) have gained significant interest in areas such as optical manipulation, quantum entanglement, and super-resolved imaging. The OAM per photon of such beams, typically Laguerre-Gaussian beams, is directly proportional to the azimuthal index l. This index is continuous in nature and a non-trivial parameter to measure. In this study, Laguerre-Gaussian beams of differing l are generated through mode conversion using microscopic spiral phase plates. The value of l depends on the refractive index of the medium surrounding the spiral phase plates. Utilising laser speckle, we demonstrate an ultra-precise measurement of the azimuthal index of the generated beams to a precision of 2 × 10⁻⁵. In turn, this enables an ultra-precise measurement of the refractive index of the medium surrounding the spiral phase plates, with a best measured precision of 6.4 × 10⁻⁷ refractive index units. Our study interrogates samples of sucrose and haemoglobin, only 300 pL in volume, within a microfluidic channel.

Integrated quantum photonics is rapidly emerging as a transformative platform for realizing scalable, chip‐based quantum technologies, from secure communication to advanced sensing and computing. At the heart of this revolution are solid‐state quantum emitters: atom‐like light sources embedded in a variety of host materials that enable single‐photon generation, quantum interference, and spin–photon coupling. We begin by discussing quantum emitters across bulk crystals, van der Waals materials, and chemically synthesized nanostructures, highlighting their performance trade‐offs and integration potential. We then examine nanophotonic cavities that enhance the light‐matter interaction, from photonic crystals to metasurfaces and Moiré resonators. Next, we discuss fabrication techniques with sub‐10 nm precision, including material‐specific etching strategies and hybrid integration schemes. Finally, we address emerging approaches for deterministic placement, cavity tuning, and on‐chip scalability. By bringing together insights from materials science, nanofabrication, and quantum optics, this Review provides a comprehensive perspective on the design and integration of high‐performance quantum emitters for scalable photonic platforms.

Enhancing light-matter interactions with photonic structures is critical in classical and quantum nanophotonics. Recently, Moiré twisted bilayer optical materials have been proposed as a promising means toward a tunable platform for nanophotonic devices. However, the realization of Moiré photonic crystal (PhC) cavities has been challenging, due to a lack of advanced nanofabrication techniques and availability of stand-alone transparent membranes. Here, we leverage the properties of the van der Waals material hexagonal boron nitride to realize Moiré bilayer PhC cavities. We design and fabricate a range of devices with controllable twist angles, with flatband modes in the visible spectral range (∼450 nm). Optical characterization confirms the presence of spatially periodic cavity modes originating from the engineered dispersion relation (flatband). Our findings present a major step toward harnessing a two-dimensional van der Waals material for the next generation of on chip, twisted nanophotonic systems.

Higher-order optical harmonics entered the realm of nanostructured solids being observed recently in optical gratings and metasurfaces with a subwavelength thickness. Structuring materials at the subwavelength scale allows us toresonantly enhance the efficiency of nonlinear processes and reduce the size of high-harmonic sources. We report the observation of up to a seventh harmonic generated from a single subwavelength resonator made of AlGaAs material. This process is enabled by careful engineering of the resonator geometry for supporting an optical mode associated with a quasi-bound state in the continuum in the mid-infrared spectral range at around λ = 3.7 μm pump wavelength. The resonator volume measures ~0.1 λ ³ . The resonant modes are excited with an azimuthally polarized tightly focused beam. We evaluate the contributions of perturbative and nonperturbative nonlinearities to the harmonic generation process. Our work proves the possibility to miniaturize solid-state sources of high harmonics to the subwavelength volumes.