Advanced Photonics Research最新文献

Conventionally, a collimated visible laser beam can only be focused to a transverse region volume with a waist of about 200 nm and an axial waist of about 1200 nm due to the wave nature of light. Several techniques have been used to bypass the diffraction limit, including a recently developed one using the emission from an optically trapped upconverting nanoparticle. This nanoparticle has a diameter smaller than 200 nm, such that it emits like a dipole into a 45° cone. Thus, not only is the emission coming from a particle smaller in size than the waist of the diffraction-limited spot but also the cone is smaller than that of the volume of a very tightly focused beam. Here, the technique is developed even further where the emission coming from a specific region of the cone is selected by an optical fiber-based pinhole in the detection path. Using this technique, a confocal depth of about 200 nm is achieved as the overlap between the emission cone and the detection volume. This would correspond to a volume of about 250 attoliters for a 1.5 μm diameter particle which can be reduced to 40 attoliters by using a 500 nm diameter particle.

In article number 2300192, Christian Frydendahl, Uriel Levy, and co-workers demonstrate a new approach where plasmonic nanostructures are pierced through the hexagonal boron nitride layers to make atomic edge contacts to the graphene, thus maintaining the advantages of encapsulation, while enabling strong enhancement of the optical response of graphene from charge transfer from plasmonic decay in the nanocavities.

In article number 2300235, Chris Sturm presents a comprehensive discussion on exceptional points (EPs) in optically anisotropic materials, their occurrence, and properties as well as the properties of the electromagnetic waves propagating along such EPs. The presence of such EPs, their spatial and spectral distribution in bulk, and semi-infinite and finite crystals are discussed.

The application prospects of ZnS stress luminescent materials cover many fields such as high-precision structural monitoring, smart materials, biomedical imaging, and new sensor technologies, which bring broad application prospects and significance to them in the fields of engineering, medicine, and scientific research. In this article, the electronic structure and optical properties of ZnS materials are successfully regulated by applying pressure and doping rare earth metals (Re), and it is found that the regulation of the luminescence properties of ZnS is the result of stress and doping interactions. Specifically, when pressure is applied or Re metal doping, the lattice structure is deformed and the atomic spacing is adjusted, which affects the electronic energy level distribution and optical properties of ZnS materials. Computational analysis of density functional theory (DFT) reveals the microscopic mechanisms behind these changes, including changes in lattice parameters, adjustment of bond length, and changes in band structure. This study provides theoretical guidance for the design and synthesis of high-performance and high-stability ZnS light-emitting materials, and is of great significance for expanding the application of ZnS in the field of lasers and sensors.

Herein, an integrated electro-optically tunable narrow-linewidth III–V laser with an output power of 738.8 μW and an intrinsic linewidth of 45.55 kHz at the C band is demonstrated. The laser cavity is constructed using a fiber Bragg grating (FBG) and a tunable Sagnac loop reflector (TSLR) fabricated on thin-film lithium niobate. The combination of the FBG and the electro-optically tunable TSLR offers the advantages of single spatial mode, single frequency, narrow linewidth, and wide wavelength tunability for the electrically pumped hybrid integrated laser, which features a frequency tuning range of 20 GHz and a tuning efficiency of 0.8 GHz V⁻¹.

Silicon photonics has found a profound place among emerging technologies in the past few decades due to several advantages. Due to a series of breakthroughs and increased funding from private and government sectors, the development of silicon photonics has accelerated especially starting from the two years 2004–2005 with a persisting and ever-growing momentum. Among various components, the silicon photonic filters that selectively pass or block particular wavelengths with a finite bandwidth have found particular interest as they are useful in signal processing in different fields ranging from optical communication to microwave photonics and quantum photonics. Herein, a comprehensive review of silicon photonic filters focusing on the four most commonly used architectures, such as microring resonators, waveguide Bragg grating, Mach–Zehnder interferometers, and arrayed waveguide grating, encapsulating basics, and guidelines, in terms of simulating tools and topologies, of realizing reconfigurable and high-performing filters for several applications, is provided. The novelty of this review relies on the fact that it summarizes these filter architectures covering a broad range of applications concisely and constructively and includes the basics, growth, and future trends, providing a clear understanding and importance of silicon photonic filters from research to commercialization perspective.

Artificial spin systems are used to solve combinatorial optimization problems by mapping them to the ground state search of the Ising model. Ising machines of various designs, in fields as diverse as photonics and electronics, have been proposed and demonstrated in recent years. One important mathematical operation required in photonic Ising machines for nearly all Hamiltonian minimization algorithms is repeated matrix–vector multiplication with the vector size limited by the physical size of the optical system. Herein, an integrated photonic Ising machine based on matrix partitioning and phase encoding, which effectively allows the use of physically small optical circuits to handle arbitrarily large spin vectors, is proposed. All the complicated calculations are carried out optically, rather than electronically, in this approach. How the required surface area of a hypothetical chip-based photonic Ising machine can be resized according to convenience, with the trade-off being the solution time, and that this trade-off can be done in a way that does not impact the algorithm's efficacy, is shown. Through simulation, the system is predicted to have a high success rate, high noise tolerance, and high error tolerance.

Three carbazole-substituted anthracene 2CbzAn, 26CbzAn, and 246CbzAn have been developed. The introduction of these carbazole substituents could generate more triplet states with energy levels close to 2× E(T1) that could successfully facilitate the triplet-triplet annihilation upconversion (TTA-UC) process to achieve high upconversion quantum yield (UCQY). This observation aligns with the Adachi theory about TTA-UC mechanisms. In organic light-emitting diode (OLED) device investigation, in a non-doped state show an external quantum efficiency (EQE_max) of 5.82% with exceptional pure-blue emission (CIEy of 0.101), and the DPaNIF doped DMPPP/26CbzAn bilayer structure reaches an impressive EQE_max of 11.12%.

Although the investigation of the propagation of electromagnetic waves in crystals dates back to the 19th century, the presence of singular optic axes in optically anisotropic materials has not been fully explored until now. Along such an axis, either a left or a right circular polarized wave can propagate without changing its polarization state. More generally, these singular optic axes belong to exceptional points (EPs) in the momentum space and correspond to a simultaneous degeneration of the eigenmodes and their propagation properties. Herein, a comprehensive discussion on EPs in optically anisotropic materials, their occurrence, and properties as well as the properties of the electromagnetic waves propagating along such EPs is presented. The presence of such EPs, their spatial and spectral distribution in bulk, and semi-infinite and finite crystals are discussed. It is shown that the presence of interfaces has a strong impact on the presence of the EPs and their spatial distribution. At an EP, the propagation of an arbitrarily polarized wave cannot be described by a superposition of two eigenmodes, as typically described in textbooks. This leads to singularities if the reflection and transmission coefficients have to be calculated. Here, two approaches are presented to overcome these limitations.

The gain factor of the optical parametric amplification (OPA) process is known to be negligible in the small scale due to low-interaction-medium length. Hence, in the nanoscale, OPA is deemed as infeasible. Therefore, in small-scale-integrated optical devices, stimulated-emission-based amplifiers (lasers) are employed instead of OPAs. In contrast, the major advantage of OPAs over lasers is that unlike lasers which only provide amplification over a narrow spectral band, OPAs provide high-gain amplification over a very large, user-controlled spectral band. In this article, it is shown that OPA can yield wideband high-gain amplification over a nanoscale beam propagation distance through dispersion engineering. This is achieved by a proper tuning of the pump (source) wave frequency, which can maximize the effective medium nonlinearity by a few orders of magnitude, while concurrently maximizing the intracavity energy density, thereby compensating for the small co-propagation distance for the input (signal) and pump beams. In this study, it is shown that an input wave can be amplified by a factor $��{�10�}^8�$ in a nanoscale cavity via precise dispersion engineering. Both empirical and computational formulations are used for the investigation, which display a reasonable agreement.