We propose a new method based on variational principle for analysis of photonic crystal (PC) slabs. Most of the methods used today treat PC slab as a three-dimensional (3D) crystal and this makes them very time and/or memory consuming. In this method we use Bloch theorem to expand the field on infinite plane waves which their amplitudes depend on the component perpendicular to the slab surface. By approximating these amplitudes with appropriate functions, we can find modes of PC slabs almost as fast as we can find modes of a two-dimensional (2D) crystal. Besides this advantage, we can also calculate radiation modes with this method which is not feasible with 3D Plane Wave Expansion (PWE) method.
The process of self-assembly is guided by the minimization of free energy, which limits the symmetries available for assembly and ultimately the usefulness of devices fabricated in this fashion. Here, we demonstrate experimentally for the first time a technique which we term light-assisted, templated self assembly. By exciting a guided-resonance mode of a photonic-crystal slab, an optical potential landscape is created above the slab which results in stably trapped, periodic patterns of particles at the potential minima. The underlying symmetry of particle clusters matches that of the photonic…
We report on enhanced fluorescence of lead sulfide quantum dots interacting with leaky modes of slab-type silicon photonic crystals. The photonic crystal slabs were fabricated supporting leaky modes in the near infrared wavelength range. Lead sulfite quantum dots which are resonant the same spectral range were prepared in a thin layer above the slab. We selectively excited the leaky modes by tuning wavelength and angle of incidence of the laser source and measured distinct resonances of enhanced fluorescence. By an appropriate experiment design, we ruled out directional light extraction effect…
Enhanced Third-Harmonic Generation in Diamond Photonic Crystal Slabs via Doubly Resonant Quasi-Bound States in the Continuum
Research Institute for Semiconductor Engineering, Hiroshima University（广岛大学半导体工程研究所）；Research Center for Advanced Science and Technology, The University of Tokyo（东京大学先进科学技术研究中心）
We study the linear- and nonlinear-optical lineshapes of metal nanoparticles (theory) and metallic photonic crystal slabs (experiment and theory). For metal nanoparticle ensembles, we show analytically and numerically that femtosecond second- or third-harmonic-generation (THG) experiments together with linear extinction measurements generally do not allow to determine the homogeneous linewidth. This is in contrast to claims of previous work in which we identify a technical mistake. For metallic photonic crystal slabs, we introduce a simple classical model of two coupled Lorentz oscillators, co…
Chiral edge-state signatures of Berry monopole merging and splitting in a bilayer photonic crystal slab with synthetic momentum
Donostia International Physics Center（多诺斯蒂亚国际物理中心）；Institute of Physics, Vietnam Academy of Science and Technology（越南科学技术院物理研究所）；Univ. Lille, CNRS, UMR 8523-PhLAM-Physique des Lasers Atomes et Molécules（里尔大学、法国国家科学研究中心、激光与原子分子物理联合研究实验室）；Advanced Polymers and Materials: Physics, Chemistry and Technology, Chemistry Faculty (UPV/EHU)（巴斯克国立自治大学/圣塞巴斯蒂安大学化学学院先进聚合物与材料物理、化学与技术系）；Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS)（韩国基础科学研究院复杂系统理论物理中心）；Institute for Interdisciplinary Research in Science and Education, ICISE（越南归仁市科学与教育跨学科研究所）；Ecole Centrale de Lyon, CNRS, INSA Lyon, Université Claude Bernard Lyon 1, CPE Lyon, CNRS, INL, UMR5270（里昂中央理工学院、法国国家科学研究中心、里昂国立应用科学学院、里昂第一大学、里昂化工学院、法国国家科学研究中心里昂纳米技术研究所）；CNRS-International-NTU-Thales Research Alliance (CINTRA), IRL 3288（法国国家科学研究中心-国际南洋理工大学-泰雷兹研究联盟）；Institut Universitaire de France (IUF)（法兰西学院）；IKERBASQUE, Basque Foundation for Science（伊克尔巴斯科奎，巴斯克科学基金会）
We present a fully three-dimensional Bloch mode expansion technique and photon Green function formalism to compute the quality factor, mode volume, and Purcell enhancement distributions of a disordered W1 photonic crystal slab waveguide in the slow-light Anderson localization regime. By considering fabrication (intrinsic) and intentional (extrinsic) disorder we find that the quality factor and Purcell enhancement statistics are well described by log-normal distributions without any fitting parameters. We also compare directly the effects of hole size fluctuations as well as fluctuations in the…
Recently, higher-order topological phases that do not obey the usual bulk-edge correspondence principle have been introduced in electronic insulators and brought into classical systems, featuring with in-gap corner/hinge states. So far, second-order topological insulators have been realized in mechanical metamaterials, microwave circuit, topolectrical circuit and acoustic metamaterials. Here, using near-field scanning measurements, we show the direct observation of corner states in second-order topological photonic crystal (PC) slabs consisting of periodic dielectric rods on a perfect electric…
We present a new paradigm in the field of photonic crystals and metamaterials, applying the resonant-state expansion (RSE) to planar photonic-crystal structures. The RSE allows us to understand and quantify optical resonances in photonic-crystal structures in terms of the analytic resonant states of a homogeneous planar waveguide. The RSE provides an efficient and reliable tool for accurate calculation of a complete set of the resonant states of a photonic-crystal slab, which is required for the correct description and a better understanding of its optical spectra. For the proof of principle, …
We study the effects of disorder on the coupling strength of coupled photonic crystal slab cavities by considering fully-3D electromagnetic calculations. Specifically, we investigate two coupled L3 cavities at 30° and 60° configurations, where the coupling strength J (or photon hopping) is extracted from the simulations in the presence of disorder. We found that the relative fluctuations of the photon hopping are more sensitive to disorder effects than the corresponding fluctuations in the eigenfrequencies of the coupled cavities. Furthermore, for the typical range of disorder in state-of-the-…
We fabricate and experimentally characterize a $H0$ photonic crystal slab nanocavity with a design optimized for maximal quality factor, $Q = 1.7$ million. The cavity, fabricated from a silicon slab, has a resonant mode at $λ= 1.59 \mathrm{μm}$ and a measured $Q$-factor of $400,000$. It displays nonlinear effects, including high-contrast optical bistability, at a threshold power among the lowest ever reported for a silicon device. With a theoretical modal volume as small as $V = 0.34(λ/n)^3$, this cavity ranks among those with the highest $Q/V$ ratios ever demonstrated, while having a small fo…
We present an all-dielectric photonic crystal structure that supports two-dimensionally confined helical topological edge states. The topological properties of the system are controlled by the crystal parameters. An interface between two regions of differing band topologies gives rise to topological edge states confined in a dielectric slab that propagate around sharp corners without backscattering. Three dimensional finite-difference time-domain calculations show these edges to be confined in the out-of-plane direction by total internal reflection. Such nanoscale photonic crystal architecture…
We develop an analytic formalism to describe dipole radiation near the Dirac cone of a two-dimensional photonic crystal slab. In contrast to earlier work, we account for all polarization effects and derive a closed-form expression for the dyadic Green's function of the geometry. Using this analytic Green's function, we demonstrate that the dipolar interaction mediated by the slab exhibits winding phases, which are key ingredients for engineering topological systems for quantum emitters, as discussed in detail in J. Perczel et al., (2018), arXiv:1810.12299. As an example, we study the coherent …
Exceptional points(EPs), branch points of complex energy surfaces at which eigenvalues and eigenvectors coalesce, are ubiquitous in non-Hermitian systems. Many novel properties and applications have been proposed around the EPs. One of the important applications is to enhance the detection sensitivity. However, due to the lack of single-handed superchiral fields, all of the proposed EP-based sensing mechanisms are only useful for the non-chiral discrimination. Here, we propose theoretically and demonstrate experimentally a new type of EP, which is a called radiation vector EP, to fulfill the h…
We introduce the first designs for high-Q photonic cavities in slab architectures in hyperuniform disordered solids displaying isotropic band gaps. Despite their disordered character, hyperuniform disordered structures have the ability to tightly confine the TE-polarised radiation in slab configurations that are readily fabricable. The architectures are based on carefully designed local modifications of otherwise unperturbed hyperuniform dielectric structures. We identify a wide range of confined cavity modes, which can be classified according to their approximate symmetry (monopole, dipole, q…
Photonic crystal nanocavities are used to enhance photoluminescence from single-walled carbon nanotubes. Micelle-encapsulated nanotubes are deposited on nanocavities within Si photonic crystal slabs and confocal microscopy is used to characterize the devices. Photoluminescence spectra and images reveal nanotube emission coupled to nanocavity modes. The cavity modes can be tuned throughout the emission wavelengths of carbon nanotubes, demonstrating the ability to enhance photoluminescence from a variety of chiralities.
We have realized and measured a GaAs nanocavity in a slab photonic crystal based on the design by Kuramochi et al. [Appl. Phys.Lett., \textbf{88}, 041112, (2006)]. We measure a quality factor Q=700,000, which proves that ultra-high Q nanocavities are also feasible in GaAs. We show that, due to larger two-photon absorption (TPA) in GaAs, nonlinearities appear at the microwatt-level and will be more functional in gallium arsenide than in silicon nanocavities.
