Photonic Crystal Research Articles

Analytical assessment based on radiative-magnetized nanomaterial viscoplastic flow configured by cylindrical regime with Darcy–Forchheimer porosity, Joule heating and chemical reaction

Nanotechnology has turn out to be a focal point, disseminating its stimulus across distinct realms of technology, science and industry, making its mark in our routine inhabits. Nanoparticles are deployed in numerous industries encompassing bio-fuels production, bio-remediation, coating, solar film, crops production, photonic crystals, material science, cosmetics and drugs because of their characteristics like higher reactivity, catalytical activity, morphology and higher adsorption capacity. In this theoretical investigation, analytical simulations are carried out for mixed convective viscoplastic nanomaterial configured by permeable elongating surface. Flow is electrically conducting and thermally radiative. Transportation expressions include multi-physical effects like Brownian diffusion, thermal source, thermophoresis and chemical reaction. Darcy–Forchheimer (D–F) porosity aspect for non-Newtonian (viscoplastic) model is introduced. Boundary-layer incompressible stretched flow is modeled deploying Prandtl’s concept. Relevant dimensionless variables are employed to obtain ordinary differential expressions from the partial ones and homotopy algorithm is deployed for computational analysis of such expressions. Consequences of dimensionless expressions occurring in transformed differential systems are evaluated via graphs. We noticed that increasing radiation factor engenders higher temperature. Besides the nanoparticles concentration diminishes when Brownian diffusion and solutal Biot factors are enlarged.

Two-wavelength non-dispersive infrared sensing systems using stacked electrically controllable photonic-crystal band-pass filters

We present a scheme of non-dispersive infrared (NDIR) sensing utilizing stacked, two-wavelength electrically controllable bandpass filters that integrate multiple quantum wells (MQWs) and photonic crystals. By appropriately designing the MQWs and photonic crystals, we realize electrically controllable filters that exhibit symmetric, narrow-band transmittance spectra with high transmittance at two target wavenumbers (1035 cm-1 and 1085 cm-1) and demonstrate independent modulation of the transmittance at each target wavenumber when the two filters are stacked. In addition, by using the proposed stacked filters, we construct two-wavelength mechanical-chopper-free NDIR systems with a single detector and demonstrate its ability to robustly measure the gas concentration even when the absolute optical power incident on the detector is varied.

New light-illuminated silk road: emerging silk fibroin-based optical biomedical sensors.

Biomedical silk protein optics has become the subject of intensive research aimed at solving the challenges associated with traditional medical devices in terms of biocompatibility and performance balance. With its significant potential for biomedical applications in the field of drug storage and wound monitoring, it is dedicated to reducing the perturbation of neighbouring tissues. The transparency and biocompatibility of silk proteins make them ideal materials in the field of optical device fabrication, effectively overcoming the challenges posed by conventional materials. In this paper, we explore in detail the complex aspects of the design, synthesis and application related to biomedical silk protein optical devices and comprehensively analyse the potential use of silk protein-centric microstructures (e.g., micropillars, microneedles, and photonic crystals) in the development of optical devices. This review also offers insights into the challenges of applying silk protein optical devices in healthcare and their future trends, aiming to provide a comprehensive overview of the advances, potential impacts and emerging research directions in the field of biomedical silk protein optical devices.

Raman enhancement via double optical resonances in all-dielectric photonic crystal slabs

All-dielectric photonic structures are an important class of substrates in surface-enhanced Raman spectroscopy (SERS), utilizing optical resonant modes to significantly enhance the electromagnetic field and amplify the Raman signals. In this study, we demonstrate the double-resonance approach to realize significant Raman enhancement using all-dielectric photonic crystal (PhC) slab. The double-resonance condition is satisfied by designing optical resonant modes in photonic bands to match frequencies of both excitation laser and Raman signals. By the fabricated PhC slab, the significant enhancement for the Raman signal of silicon is demonstrated. The enhanced Raman signals exhibit a uniform distribution on the PhC slab. The method of Raman enhancement via double optical resonances can advance the field of all-dielectric SERS and holds potential for future SERS applications.

Single vector mode transmission in hollow-core photonic bandgap fiber based on surface mode coupling effect

Single vector mode transmission in hollow-core photonic bandgap fiber based on surface mode coupling effect

Frequency shift keying using photonic crystal based ring cavity resonator

Frequency shift keying using photonic crystal based ring cavity resonator

Investigation and Characterization of Physical Properties and Phonon modes of ZnO/ PVA/PANI for Photonic Crystals application

Investigation and Characterization of Physical Properties and Phonon modes of ZnO/ PVA/PANI for Photonic Crystals application

Ultrahigh-[formula omitted] Fano resonance in a cavity-waveguide coupled system based on second-order topological photonic crystals with elliptical holes

We present a novel configuration of second-order topological photonic crystal (SOTPC) comprising interconnected dielectric material with elliptical air holes. Based on this SOTPC design, we construct a topological corner state (TCS) cavity and a topological edge state (TES) waveguide. Through the coupling of the TCS cavity with the TES waveguide, we establish a topological cavity-waveguide coupled system (TCWCS) that exhibits an ultrasharp asymmetric topological Fano resonance. Numerical simulations demonstrate that the proposed TCWCS achieves an exceptionally high quality factor exceeding 108, surpassing previously reported results by several orders of magnitude. Moreover, the refractive index sensing application implemented with TCWCS shows a sensitivity of 278 nm/RIU and a figure of merit surpassing 107 1/RIU. Notably, our simulations reveal that the lineshape and quality factor of the Fano resonance, as well as the index sensing performance in the TCWCS, are highly robust against structural defects. The demonstrated capabilities of the TCWCS open up avenues for further exploration and development in the field of topological photonics based on our proposed SOTPC.

Broadband asymmetric absorption-transmission and double-band rasorber of electromagnetic waves based on superconductor ceramics metastructures-photonic crystals

In this paper, a kind of superconductor ceramics metastructure-photonic crystals (SCMPC) is proposed to investigate the absorption and transmission properties of electromagnetic waves (EW) by combining a metastructure with multiple degrees of freedom regulation and strong energy localization characteristics of photonic crystals. Firstly, for the periodically aligned SCMPC, EW mainly realizes absorption in forward propagation and transmission in backward case. The relative bandwidth (RB) for both forward absorptivity and backward transmittance greater than 0.9 is 2.7 %, and the operating bandwidth (OB) is 696 ∼ 715 terahertz (THz), which is an asymmetric absorption-transmission (AAT) characteristics. Importantly, the periodically aligned SCMPC can realize the double-band rasorber phenomenon, and the forward EW exhibits an absorption-transmission-absorption phenomenon with OBs of 644.2 ∼ 671.1 THz, 700.9 ∼ 742.1 THz, and 766.8 ∼ 784.2 THz. RBs with absorption and transmissivity greater than 0.8 are 4.1 %, 5.7 %, and 2.2 %, respectively, and the backward EW one is mainly transmitted. To optimize AAT, a quasi-periodic Octonacci sequence-aligned SCMPC is introduced. The results show that the maximum OB of forward absorption and backward transmission is 428.3 ∼ 670.5 THz and RB is 44.1 %, achieving favorable broadband AAT. In addition, the effects of temperatures, dielectric thicknesses, and stacking numbers on AAT are also investigated in detail. In conclusion, AAT has promising applications in unidirectional optical transmission, photodiodes, optical isolators, etc.

Self-induced optical pulling in complex photonic band structure

The photonic band gap effect has been proposed to achieve a gradient-induced long-range optical pulling force, but how the properties of the photonic band gap affect the optical pulling force remains to be revealed. In this work, based on the theory of complex photonic band and Einstein–Laub formulation of force density, a concise formula is developed to investigate such unusual optical pulling force. It indicates that the optical pulling force is mainly decided by the imaginary part of the wave vector of evanescent mode in the photonic band gap and the refractive index of the object. A larger imaginary part of the wave vector and a higher refractive index of the object typically result in a larger optical pulling force, which is verified by the numerical simulation. In addition, a critical length is defined to predict the occurrence of optical pulling force. Our work gives an insight into such an optical pulling force based on the complex photonic band and offers guidance for achieving a larger optical pulling force, which is very beneficial to optical sorting and optical conveying.

Tutorial 2.0: computing topological invariants in 3D photonic crystals

The field of topological photonics has been on the rise due to its versatility in manufacturing and its applications as topological lasers or unidirectional waveguides. Contrary to 1D or 2D photonic crystals, the transversal and vectorial nature of light in 3D precludes using standard methods for diagnosing topology. This tutorial describes the problems that emerge in computing topological invariants in 3D photonic crystals and the diverse strategies for overcoming them. Firstly, we introduce the fundamentals of light propagation in 3D periodic media and expose the complications of directly implementing the usual topological diagnosis tools. Secondly, we describe the properties of electromagnetic Wilson loops and how they can be used to diagnose topology and compute topological invariants in 3D photonic crystals. Finally, we apply the previously described methods to several examples of 3D photonic crystals showing different topological phases, such as Weyl nodes and walls, 3D photonic Chern insulators, and photonic axion insulators.

Modelling of photonic crystal based ring resonator sensor for cancer detection using infrared laser

Modelling of photonic crystal based ring resonator sensor for cancer detection using infrared laser

Directed crystalline symmetry transformation of blue-phase liquid crystals by reverse electrostriction

Soft-matter-based photonic crystals like blue-phase liquid crystals (BPLC) have potential applications in wide-ranging photonic and bio-chemical systems. To date, however, there are limitations in the fabrication of large monocrystalline BPLCs. Traditional crystal-growth process involves the transition from a high-temperature disordered phase to an ordered (blue) phase and is generally slow (takes hours) with limited achievable lattice structures, and efforts to improve molecular alignment through post-crystallization field application typically prove ineffective. Here we report a systematic study on the molecular self-assembly dynamics of BPLC starting from a highly ordered phase in which all molecules are unidirectionally aligned by a strong electric field. We have discovered that, near the high-temperature end of the blue phase, if the applied field strength is then switched to an intermediate level or simply turned off, large-area monocrystalline BPLCs of various symmetries (tetragonal, orthorhombic, cubic) can be formed in minutes. Subsequent temperature tuning of the single crystal at a fixed applied field allows access to different lattice parameters and the formation of never-before-seen monoclinic structures. The formed crystals remain stable upon field removal. The diversity of stable monocrystalline BPLCs with widely tunable crystalline symmetries, band structures, and optical dispersions will significantly improve and expand their application potentials.

The role of photonic crystal based architectures on tailoring the laser induced fluorescence from green emitting cesium lead bromide nanocrystals

Researchers have long been fascinated by fluorescence and its potential to be boosted as it unlocks a treasure trove of promising applications. In this context, this experimental study investigates the amplification of laser induced fluorescence (LIF) emission from cesium lead bromide (CsPbBr3) perovskite nanocrystals (PNC) using two distinct all-polymer photonic crystal (PC) architectures made of poly 9-vinyl carbazole (PVK) and cellulose acetate (CA) as high and low refractive index (RI) layers, respectively. First structure is a photonic crystal micro cavity (PCMC) where PNC incorporated PVK (PNC:PVK) polymer matrix forms the defect layer sandwiched between two similar PCs. In the second structure, PNC:PVK composite itself functions as high RI layers within the PC. These two designs exploit different mechanisms to achieve fluorescence enhancement. The findings demonstrate the promise of simple, solution processed polymer PCs on applications demanding intensified fluorescence output and pave way to the development of flexible photonic devices capable of manipulating light emission.

Tunable temperature-responsive photonic ionogels with dual signals output

Photonic ionogels with dual electrical and optical output have been intensively studied. However, tunable temperature-responsive photonic ionogel assembled by thermosensitive nanogels has not been studied yet. Herein, an innovative approach to fabricate photonic ionogels has been developed for smart wearable devices with tunable temperature sensitivity and structural color. Firstly, poly(isopropylacrylamide-r-phenylmaleanilic acid) P(NIPAm-r-NPMA) nanogels self-assemble into photonic crystals in 2-hydroxyethyl acrylate (HEA), water, and the ionic liquid of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate. And then robust photonic ionogels are developed through a polymerization of 2-hydroxyethyl acrylate crosslinked by poly(ethylene glycol) diacrylate (PEGDA). The incorporation of the ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, enhances the mechanical strength of photonic ionogels and tunes the temperature-sensitivity of the ionogels, making them adaptable to various environmental conditions. The findings demonstrate that these ionogels can serve dual functions in smart wearable devices, combining electrical and optical signal outputs due to the conductivity of the ionic liquid and structural color from the nanogel assembly. The resultant photonic ionogels exhibit exceptional substrate adhesion, mechanical stability, and fast resilience. More significantly, the nanogels within these ionogels serve as the building blocks of photonic crystals (PCs) endow with angle-independent coloration and enhance stretchability beyond 200 %, while the stretchability of the ionogles without the nanogels is only about 100 %. Our photonic ionogels with tunable temperature-sensitivity and dual outputs will open an avenue to the development of the innovative smart wearable devices.

Bio-inspired synergistic humidity-responsive photonic system for security printing and information encryption

The proliferation of counterfeiting necessitates an urgent need for enhanced technique to safeguard the authenticity of sensitive items. Inspired by the elytra of Tmesisternus isabellae beetles, we designed a new synergistic humidity responsive photonic system (SHRPS) for security printing based on high quality photonic paper and active ink. The photonic paper itself is not sensitive to humidity; only the targeted areas activated by the active ink exhibit humidity responsiveness. We investigated factors influencing humidity responsiveness, including monomer composition, pH of active ink, and treatment period. We found the optimal monomer mixture contains 40% acrylic acid, and the active ink pH is 13. We also applied a scalable method to fabricate photonic paper, successfully overcome the challenge of large-scale fabrication of photonic crystals at room temperature. By integrating the perfect pair of SHRPS and inkjet printer, concealed information with various sizes and resolutions can be printed, invisible in ambient humidity and revealed by blowing air, presenting various humidity responsive ability of SHRPS for multilevel information encryption, which opens a new window for security printing system.

Tunable polymer-based ternary one-dimensional photonic crystal with PVDF piezoelectric layer in the THz spectrum

This research introduces an innovative method for crafting adjustable one-dimensional photonic crystals by integrating a polyvinylidene fluoride (PVDF) piezoelectric layer into a ternary polymer structure. The incorporation of PVDF as a piezoelectric polymer in the photonic crystal allows for the simulation of an electric field sensitive photonic crystal. Two structures of the photonic crystal are examined, one with a defect layer and one without, while the impact of piezoelectric parameters on the transmission spectrum is scrutinized. The computational outcomes clearly demonstrate that the photonic band gap can be efficiently modified by applying an external electric field in the THz frequency. Incorporating a defect mode that is sensitive to electric field allows for the creation of a narrow bandpass region (∼ 5 GHz) within a bandgap. This narrow region has the capacity to be precisely modified through the application of an external electrical field. This distinctive design proposal provides a means to govern and modify the optical characteristics of the crystal, rendering it a promising candidate for diverse photonic applications.

Non-Bloch theory for spatiotemporal photonic crystals assisted by continuum effective medium

As one indispensable type of nonreciprocal mechanism, a system with temporal modulations is intrinsically open in the physical sense and inevitably non-Hermitian, but the space and time degrees of freedom are nonseparable in a large variety of circumstances, which restrains the application of the non-Bloch band theory. Here, we investigate the spatially photonic crystals (PhCs) composed of spatiotemporal modulation materials (STMs) and homogeneous media, dubbed as the STMPhC, wherein the spatial and temporal modulations are deliberately designed to be correlated. To bypass the difficulty of the spatiotemporal correlation, we first employ the effective medium theory to account for the dispersion of fundamental bands under the influence of Floquet sidebands. Based on the continuum generalized Brillouin zone condition, we then analytically give the criteria for the existence of the non-Hermitian skin effect in the STM. Assisted by developing a numerical method that embeds the plane wave expansion in the transfer matrix, we establish the non-Bloch band theory for the low-frequency Floquet bands in the STMPhCs, in which the identification of the generalized Brillouin zone is central. We finally delve into the topological properties, including non-Bloch Zak phases and non-Bloch bulk-boundary correspondence. Our work validates the idea that the effective medium assists the non-Bloch band theory applied to the STMPhCs, which delivers a prescription to broaden the horizons of non-Bloch theory. Published by the American Physical Society 2024

Polarization-Independent Perfect Absorption in Monolayer Black Phosphorus Metasurfaces at Terahertz Frequencies via Critical Coupling.

Two-dimensional (2D) materials, which possess rich underlying physical properties that can provide the potential for designing more efficient and compact optoelectronic devices, have attracted great interest among scientists. Due to the atomic-scale thickness and the anisotropy of in-plane conductivity, 2D black phosphorus (BP) exhibits a polarization-dependent absorption spectrum with low absorption, which limits its further development in polarization-independent applications such as light absorbers and sensors. In this paper, a polarization-independent perfect absorber in the terahertz band is proposed, which is composed of a patterned BP monolayer deposited on a lossless photonic crystal (PC) slab with a back reflection mirror. The absorption of the patterned BP monolayer can reach 100% at resonant frequencies through the critical coupling mechanism of guided resonance. Moreover, the absorber exhibits polarization-independent absorption characteristics for vertically incident light, which are attributed to the 4-fold rotational symmetry of the PC substrate and the patterned BP monolayer deposited on it. This work opens up the possibility of fabricating optically polarization-independent devices based on single-layer 2D anisotropic materials.

Theoretical study of a tunable optical device on the base of magnetoactive cholesteric liquid crystals

We investigated the light reflection from half-space of cholesteric liquid crystal (CLC) being in external static magnetic field directed along the helix axis at normal light incidence. In this case there appear three photonic band gaps (PBGs) and these bands can be tuned in large intervals. We found the eigenpolarizations (EPs) at reflection of light from half-space and investigated their peculiarities. We have shown that in the absence both of absorption and of external magnetic field and at minimal influence of dielectric boundary (when the dielectric permittivity of isotropic half-space which borders with CLC half-space is equal to the CLC's mean dielectric permittivity) these polarizations are orthogonal. While, in the presence of external magnetic field they become quasi-orthogonal everywhere outside the main PBG (which exist also at the absence of external magnetic field), and they are significantly non-orthogonal within the main PBG. At some values of helix pitch they become significantly non-orthogonal practically everywhere. Moreover, in this case there exist some special points where the EPs degenerate. This system can apply as tunable narrow-band or broad-band filter and mirror, a highly tunable broad/narrow-band optical diode, and other devices.