Plasmonic Photonic Crystal Research Articles

Supersensitive sensing based on upconversion nanoparticles through cascade photon amplification at single-particle level

Single-particle sensing strategy is expected to achieve super-sensitivity with extremely low detection limit by improving the contact surface with targeted object and excluding the statistical effect of nanoparticle ensembles. However, single-particle sensing based on upconversion nanoparticles (UCNPs) is rarely reported, limited by the detection difficulty of single particles. Herein, we designed a cascade photon amplification structure of surface plasmonic photonic crystals consisting of polymethyl methacrylate (PMMA) opal photonic crystals (OPCs) with plasmonic CsxWO3 NPs onto its surface voids. Finite-difference time-domain simulations and atomic force microscopy (AFM) characterization evidence that UCNPs at single-particle level (abbreviated as UCNP) are located at the maximum amplification of optical field. Combined with the advanced fluorescence microscope equipped with AFM, the upconversion emissions of single NaYF4:Yb3+, Er3+ NP (~45 nm) are greatly boosted ~1600 folds along with lower pumping thresholds by cascade photon amplification effect for the first time. As a proof of concept, such enhanced UCNP is employed as a fluorescent probe to develop a novel UCNP senor for supersensitive dithiothreitol detection with a detection limit of 0.25 nM, two orders of magnitude lower than the previous reports. This work provides a new attempt to develop high performance of UCNP for constructing supersensitive sensors.

Upconversion luminescence enhancement of the composite films by coupling local surface plasmon effect and photonic crystals effect

Upconversion luminescence enhancement of the composite films by coupling local surface plasmon effect and photonic crystals effect

Efficient Partial Discharge Detection by Plasmonic Photonic Crystal Fiber Sensor With Bimetallic Grating

In this article, a new approach for optical partial discharge (PD) detection in gas-insulted systems is introduced for the first time to the best of our knowledge. The suggested sensor is based on plasmonic D-shaped photonic crystal fiber (PCF). Further, bimetallic grating structure of Ag/Au is utilized to enhance the sensor sensitivity. For light detection, methyl-red-doped poly (methyl methacrylate) polymer (MR-PMMA) is used as a sensing material for its photochromic characteristics and its fast response to visible light radiation. At resonance, good coupling occurs between the surface plasmon mode and the core guided mode. The radiated light intensity reflects the charge magnitude of the occurred PD process which can be detected by calculating the shift in the resonance wavelength of the loss spectra. The structural geometrical parameters are studied to improve the sensing performance using full vectorial finite-element method. The proposed sensor achieves high sensitivity of 667 pm/mW<inline-formula> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula>cm^&#x2212;2 with a linear performance with the light intensity. Moreover, the proposed sensor has advantages of simple and compact design, fabrication feasibility, electromagnetic interference immunity, fast response, and high sensitivity relative to conventional PD detection techniques using electrical methods. The designed sensor can be also utilized for laboratory testing and it could be evolved to accomplish real-time detection of PD phenomenon in gas-insulted systems.

Plasmonic Photonic Crystal Mirror for Long-Lived Interlayer Exciton Generation

Interlayer excitons in van der Waals heterostructures of two-dimensional transition-metal dichalcogenides have recently emerged as a fascinating platform for quantum many-body effects, long-range interactions, and optovalleytronic applications. The practical implementation of such phenomena and applications requires further development of the long-lived character of interlayer excitons. Whereas material developments have successfully enhanced the nonradiative lifetime, the out-of-plane polarization nature of the interlayer excitons has made it challenging to improve the radiative lifetime with conventional photonic mirrors. Here, we propose and systematically analyze a plasmonic photonic crystal (PPhC) mirror that can increase the radiative lifetime of interlayer excitons by 2 orders of magnitude. Based on the vacuum field transition, the PPhC mirror supports spatially uniform radiative decay suppression over its territory, which is crucial for engineering the interlayer excitons not localized at a specific position. The PPhC mirror platform offers new possibilities for realizing long-lived interlayer exciton-based nanodevices.

Spectral Engineering of Tamm Plasmon Resonances in Dielectric Nanoporous Photonic Crystal Sensors.

Model light-confining Tamm plasmon cavities based on gold-coated nanoporous anodic alumina photonic crystals (TMM-NAA-PCs) with spectrally tunable resonance bands were engineered. Laplacian and Lorentzian NAA-PCs produced by a modified Gaussian-like pulse anodization approach showed well-resolved, high-quality photonic stopbands, the position of which was precisely controlled across the visible spectrum by the periodicity in the input anodization profile. These PC structures were used as a platform material to develop highly reflective distributed Bragg mirrors, the top sides of which were coated with a thin gold film. The resulting nanoporous hybrid plasmonic-photonic crystals showed strong light-confining properties attributed to Tamm plasmon resonances at three specific positions of the visible spectrum. These structures achieved high sensitivity to changes in refractive index, with a sensitivity of ∼106 nm RIU-1. The optical sensitivity of TMM-NAA-PCs was assessed in real time, using a model chemically selective binding interaction between thiol-containing molecules and gold. The optical sensitivity was found to rely linearly on the spectral position of the Tamm resonance band, for both Laplacian and Lorentzian TMM-NAA-PCs. The density of self-assembled monolayers of thiol-containing analyte molecules formed on the surface of the metallic film directly contributes to the dependence of sensitivity on TMM resonance position in these optical transducers. Our findings provide opportunities to integrate TMM modes in NAA-based photonic crystal structures, with promising potential for optical technologies and applications requiring high-quality surface plasmon resonance bands.

Design of a hybrid photonic-plasmonic crystal refractive index sensor for highly sensitive and high-resolution sensing applications

In this paper, an optical refractive index sensor based on a hybrid photonic-plasmonic crystal (PhPlC) topology, in which some metal nano-rods are embedded in a rod-type GaAs photonic crystal (PhC) lattice, is proposed. The FDTD method is used for numerical simulation of the sensor. The simulation results illustrate a fairly high sensitivity of 1350 nm/RIU, a high figure of merit (FoM) of 488 RIU−1, and a detection of limit of 2.04×10−4 RIU. The sensitivity of the PhC sensor is dramatically enhanced by employing the excitations of plasmonic mods of the metal nano-rods in the sensor structure. The sensitivity and FoM of the proposed sensor are significantly improved compared to the results published in the literature. The higher sensitivity and the larger FoM are the two important features of the proposed sensor which make it an incredibly suitable candidate for sensing applications in optic communication wavelengths.

Design of tunable ring-shaped plasmonic photonic crystal filters infiltrated with optical fluids

Three different designs of plasmonic photonic crystal filters (two-channel, three-channel, and four-channel) are proposed and considered. The photonic crystal structures consist of standing rods made of Ag and GaAs, whereby introducing different simple or ring-shaped defects, two-, three-, or four-port filters are realized. Optical fluid is used instead of air as the background material, owing to its versatile benefits. By utilizing different combinations of optical fluids and plasmonic materials, multichannel filters are obtained which can function better by improving the structural parameters such as the rod’s radius. Considering the four-port filter, its applications as the power splitter are also investigated. For tuning the filter properties such as the resonance peak’s value and wavelength, impacts of Ag and GaAs rod radius on the transmission spectrum are examined. The following resonance peak’s value and FWHM are obtained for the proposed structures: two-channel filter (0.9, 4 nm), three-channel filter (0.8, 2 nm), four-channel filter (0.5, 10 nm). The proposed designed filters can be utilized in the photonic integrated circuits as well as the nanophotonics devices for medical and industrial applications.

Ultracompact Energy Transfer in Anapole-based Metachains.

Realization of electromagnetic energy confinement beyond the diffraction limit is crucial for high-performance on-chip devices. Herein we construct an array of nonradiative anapoles that originate from the destructive far-field interference of electric and toroidal dipole modes to achieve ultracompact and high-efficiency electromagnetic energy transfer without the coupler. We experimentally investigate the proposed metachain at mid-infrared frequencies and give the first near-field experimental evidence of anapole-based energy transfer, in which the spatial profile of the anapole mode is also unambiguously identified on the nanoscale. We further demonstrate that the metachain is intrinsically lossless and scalable at infrared wavelengths, realizing a 90° bending loss down to 0.32 dB at the optical communication wavelength. The present scheme bridges the gap between the energy confinement and the transfer of anapoles and opens a new gate for more compactly integrated photonic and energy devices, which can operate in a broad spectral range.

Nanoimprint Lithography Facilitated Plasmonic‐Photonic Coupling for Enhanced Photoconductivity and Photocatalysis

AbstractImprint lithography has emerged as a reliable, reproducible, and rapid method for patterning colloidal nanostructures. As a promising alternative to top‐down lithographic approaches, the fabrication of nanodevices has thus become effective and straightforward. In this study, a fusion of interference lithography (IL) and nanosphere imprint lithography on various target substrates ranging from carbon film on transmission electron microscope grid to inorganic and dopable polymer semiconductor is reported. 1D plasmonic photonic crystals are printed with 75% yield on the centimeter scale using colloidal ink and an IL‐produced polydimethylsiloxane stamp. Atomically smooth facet, single‐crystalline, and monodisperse colloidal building blocks of gold (Au) nanoparticles are used to print 1D plasmonic grating on top of a titanium dioxide (TiO2) slab waveguide, producing waveguide‐plasmon polariton modes with superior 10 nm spectral line‐width. Plasmon‐induced hot electrons are confirmed via two‐terminal current measurements with increased photoresponsivity under guiding conditions. The fabricated hybrid structure with Au/TiO2 heterojunction enhances photocatalytic processes like degradation of methyl orange (MO) dye molecules using the generated hot electrons. This simple colloidal printing technique demonstrated on silicon, glass, Au film, and naphthalenediimide polymer thus marks an important milestone for large‐scale implementation in optoelectronic devices.

All-optical switch based on novel physics effects

All-optical switches are among the most important parts of integrated photonics. Ultrahigh speed and ultralow energy consumption are two necessary indexes of all-optical switches. Traditionally, all-optical switches are based on concepts such as micro-ring resonators, surface plasmon polaritons, photonic crystals, and metamaterials. However, such platforms cannot satisfy the demand for high performance of all-optical switches. To overcome the limited response time and energy consumption, recent studies have introduced new applications of such physics as parity–time symmetry, exceptional points, topological insulators, and bound states in a continuum. Such physical concepts not only provide promising research avenues for the all-optical switch but also broaden the design channel. This is expected to achieve ultracompact, ultrafast, and high-capacity all-optical information processing.

Tunable Fano resonance in one-dimensional magnetized plasmon photonic crystals

In this paper, the reflection characteristics of one-dimensional (1D) magnetized plasma photonic crystals (MPPCs) are studied by using the transfer matrix method. The given structure is made up of binary photonic crystals whose unit only contains two plasma layers with different plasma frequencies and a dielectric material layer at the end. The phenomenon of Fano resonance can be realized by such a simple periodic asymmetric structure. By applying the external applied magnetic field, the properties and transmission metrics of the presented MPPCs can be achieved. The numerical results reveal that two narrow and asymmetric linear reflection peaks will appear, and a phenomenon of Fano resonance can be observed. The influences of refractive index, period constant, incident angle, and magnetized plasma parameters on the obtained Fano resonance also are investigated. The analyzed results demonstrate that the tailored Fano resonance can appear in the proposed 1D MPPCs, and the above parameters can affect its features. The stated 1D MPPCs can be used in the sensors, slow light optical devices, and so on.

DNA Hybridization Detection based on Plasmonic Photonic Crystal Fiber

A novel design of surface plasmon (SP) photonic crystal fiber (PCF) for DNA hybridization detection is proposed and analyzed. The suggested biosensor relies on plasmonic D-shaped PCF configuration. Accordingly, the core guided mode in the silica core is coupled with the SP mode near the plasmonic layer. The resonance wavelength is sensitive to the DNA hybridization process. Therefore, the suggested bio-sensor is studied to maximize the DNA hybridization detection sensitivity by adjusting the structural geometrical parameters. The numerical results are obtained using full vectorial finite element method with perfectly matched layer boundary condition and non-uniform meshing capabilities. The reported D-shaped PCF offers high wavelength sensitivity of 405.4 nm/RIU with a corresponding amplitude sensitivity of 5.65 RIU−1. Consequently, the applications based on DNA classification can be potentially implemented by the reported biosensor.

Electro-optical switch based on one-dimensional graphene-plasmonic crystals

In the present study, an electro-optical switch using one-dimensional plasmonic photonic crystals and bilayer graphene was demonstrated experimentally and theoretically. The optical modes of band gap in crystal can be tuned due to the unique optical properties of plasmonic surface resonance at grating and graphene layers. In addition, the excitation of the periodic arrays of metallic resulted in exciting plasmonic surface lattice resonance and creating two reflectance modes for magnetic polarization at 54° incidence angle. Further, the chemical potential of graphene was controlled by applying a gate voltage to achieve an optoelectronic switching operation. Applying voltage of 1 V led to a sharp increase in the relative permittivity of bilayer graphene around the first resonance. Thus, the light was absorbed, its intensity deceased, and the plasmonic resonance wavelength shifted by a value of ~9 nm. Based on the results, using this new kind of structures had advantages such as small size, low power consumption, easier fabrication, and less manufacturing cost, as well as the high controllability of conductivity compared to the other methods.

Optical nanomaterials with focus on rare earth doped oxide: A Review

Optical nanomaterials (ONMs) have attracted significant attention of the global research community owing to their several superior advantages. Some of the ONMs depict negligible photobleaching, bright emission, large electron-hole overlap integral, ease of coating on any surface, large Stoke/Antistoke shifts, higher photostabilites, easy to incorporate inside human body etc. These properties make them technologically highly efficient which helps in minimizing the global issue of energy crisis and improving the standard of living of common man. Several aspects of ONMs such as plasmonic nanomaterials, quantum dots, photonic crystals, and rare earth doped nanoparticles have been discussed. For covering various categories of luminescent nanomaterials (LNMs) based on composition, a brief introduction and importance of metal nanoclusters, carbon nano dots, organic-inorganic nanocomposites, and metal doped nanoparticles have been also included. This review article gives very concise overview of rare earth doped oxide nanoparticles covering several important aspects such as rare earth ion (RE) as dopant, oxide-based host, nanophosphors etc. The importance of LNMs, their advantages as well as drawbacks are also highlighted. Technologically important types of RE doped oxide nanoparticles pertaining to downconversion, upconversion, persistence and radioluminescence are also explained and covered in detail in this review article. Several recent applications involving LNMs in bioimaging, solar cell, thermal sensor, biosensor, anti-counterfeiting etc are explained. In the last section of the review, a comparison between nano and bulk rare earth doped oxide LNMs are discussed in terms of several photophysical properties such as dopant local symmetry, Stark splitting, emission intensity, luminescence lifetime, host to dopant energy transfer, quantum yield etc. Finally, this review article is concluded with summary, outlook, challenges, and future scope on the use of LNMs. Several important aspects of LNMs with focus on RE doped oxide nanoparticles have been covered in this review article which will help general readers in their further research, in this important area, for development of both fundamental sciences and applications involving LNMs.

Controlled self-assembly of plasmon-based photonic nanocrystals for high performance photonic technologies

• The self-assembled plasmonic nano-enabled photonic crystals (PCs) have been studied as promising platforms to develop next-generation photonic and opto-electronic devices. • In this review, we attempt to describe the fundamentals of self-assembled colloidal plasmonic nanostructures and various applications of such devices. • Different important aspects, such as interaction between metal NPs (MNPs) and non-metal 3-D crystals, effect of NPs on the spectral properties of materials, the mechanism of plasmonic based PCs, and related challenges and their possible solutions have been demonstrated crucially. • The advancements in the self-assembly based plasmonic PCs and their applications are discussed carefully. • We believe that nano-enabled self-assembled plasmonic crystals are better candidates of nanostructures to advance photonic technologies with reduced formfactor and high performance. The self-assembled plasmonic nano-enabled photonic crystals (PCs)have been studied as promising platforms to develop next-generation photonic and opto-electronic devices. In this review, we attempt to describe the fundamentals of self-assembled colloidal plasmonic nanostructures and various applications of such devices. Different important aspects, such as interaction between metal NPs (MNPs) and non-metal 3-D crystals, effect of NPs on the spectral properties of materials, the mechanism of plasmonic based PCs, and related challenges and their possible solutions have been demonstrated crucially. The advancements in the self-assembly based plasmonic PCs and their applications are discussed carefully. We believe that nano-enabled self-assembled plasmonic crystals are better candidates of nanostructures to advance photonic technologies with reduced form factor and high performance.

State-of-art plasmonic photonic crystals based on self-assembled nanostructures

Controlled self-assembly of plasmonic photonic nanostructures provides a cost-effective and efficient methodology to expand plasmonic photonic nano-platforms with unique, tunable, and coupled optical characteristics.

A tunable narrow-band plasma photonic crystal filter based on bound state

Photonic crystals are widely used in a class of narrow-band frequency selective filter due to their excellent ability to control electromagnetic waves, in which the working frequency depends on the structural parameters of the point defect resonant cavity of the photonic crystal, and the introduction of some dispersive media into the cavity makes the filter adjustable. In general, this kind of cavity-filter is very sensitive to the parameter disturbance of the cavity, and the quality factor of the filter can be reduced significantly by material loss. On the other hand, some studies have shown that there may be bound states at the interface between two different photonic crystals, and the bound state is often accompanied by narrow band and high transmittance, which implies that a narrow-band filter based on bound states is feasible. Importantly, filters based on bound states may be resistant to material loss to some degree. In this paper, a bound state related tunable narrow-band filter composed of a one-dimensional photonic crystal and a two-dimensional plasma photonic crystal is proposed, and the working frequency of the filter is located in the common band gap of the two photonic crystals. The COMSOL Multiphysics finite element simulation software is used to study the influences of geometric parameters of the one-dimensional photonic crystal and plasma parameters on the performance of the filter. It is found that the closer to each other the center frequencies and depths of the two different forbidden bands are, the greater the peak transmittance of the filter, in which the center frequency dominates, will be. On the other hand, the working frequency of the filter is directly proportional to plasma density and inversely proportional to collision frequency. The quality factor of the filter first increases and then decreases with the increase of plasma density, and decreases with the increase of collision frequency. The peak transmittance of the filter first increases and then decreases with the increase of plasma density, and decreases with the increase of plasma collision frequency. Finally, with the increase of collision frequency, both the peak transmittance and the quality factor decrease slightly, which indicates that the filter has a certain resistance to plasma loss. We believe that this work is helpful in investigating some new plasmonic photonic crystal filters.

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications.

This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.

Surface-enhanced fluorescence imaging on linear arrays of plasmonic half-shells.

Here, we perform a Surface-Enhanced Fluorescence (SEF) intensity and lifetime imaging study on linear arrays of silver half-shells (LASHSs), a class of polarization-sensitive hybrid colloidal photonic-plasmonic crystal unexplored previously in SEF. By combining fluorescence lifetime imaging microscopy, scanning confocal fluorescence imaging, Rayleigh scattering imaging, optical microscopy, and finite difference time domain simulations, we identify with high accuracy the spatial locations where SEF effects (intensity increase and lifetime decrease) take place. These locations are the junctions/crevices between adjacent half-shells in the LASHS and locations of high electromagnetic field enhancement and strong emitter-plasmon interactions, as confirmed also by simulated field maps. Such detailed knowledge of the distributed SEF enhancements and lifetime modification distribution, with respect to topography, should prove useful for improved future evaluations of SEF enhancement factors and a more rational design of efficiency-optimized SEF substrates. These linear arrays of metal-coated microspheres expand the family of hybrid colloidal photonic-plasmonic crystals, platforms with potential for applications in optoelectronic devices, fluorescence-based (bio)chemical sensing, or medical assays. In particular, due to the polarized optical response of these LASHSs, specific applications such as hidden tags for anti-counterfeiting or plasmon-enhanced photodetection can be foreseen.

Improving the surface layer structure in opal-like plasmonic-photonic crystals for efficient excitation of optical Tamm states

We investigate the transmission of light through three-dimensional structures in opal-like plasmonic-photonic crystals with an Au surface layer of different geometries. We study how the inclusion of buffer layers of various forms affects the spectral characteristics of the structures. Three-dimensional photonic crystals have significant advantages over one-dimensional ones since they display a complete photonic bandgap and porosity. Controlling the spectral characteristics of the hybrid plasmonic-photonic mode is an important task that offers the possibility of creating tunable devices based on such structures. In this work we show that the optical properties of structures with different shapes of the surface layer do not depend on light polarization, except for structures with a corrugated Au layer and a corrugated buffer layer. The bandwidth of a structure with a corrugated Au layer is smaller and shows polarization sensitivity in contrast to a structure with a smooth Au layer. The optical characteristics of hybrid structures undergo significant changes when buffer layers of various shapes are introduced between the photonic crystal and the Au layer. The width of the peak in the transmission spectra changes and its intensity increases against the background after the improvement of the structure of the plasmonic-photonic crystal. Thus, opal-like plasmonic-photonic crystals with different structure of the surface layer have spectral features that can be used in integrated circuits, biosensors, and resonators. • The inclusion of buffer layers of various forms affects the spectral characteristics of the plasmonic-photonic crystal. • The optical properties of different structures do not depend on light polarization. • As an exception, the bandwidth of a structure with a corrugated Au&buffer layers shows polarization sensitivity. • The width and intensity of the peak changes after the improvement of the plasmonic-photonic crystal.