Hybrid Plasmonic Photonic Crystal Research Articles

Hybridization of surface plasmons and photonic crystal resonators for high-sensitivity and high-resolution sensing applications.

In this paper, an optical refractive index (RI) sensor based on a hybrid plasmonic-photonic crystal (P-PhC) is designed. In the sensor's structure, some metallic rods are embedded in a rod-type photonic crystal (PhC) structure. Numerical simulations are performed based on the finite-difference time-domain (FDTD) method. The obtained results illustrate that the localized surface plasmons (LSP) induced by metallic rods can be excited in a PhC lattice to generate a hybrid P-PhC mode. According to the results, the hybrid mode provides unique opportunities. Using metallic rods in the coupling regions between waveguides and the resonant cavity significantly increases the interaction of the optical field and analyte inside the cavity. The simulation results reveal that high sensitivity of 1672nm/RIU and an excellent figure of merit (FoM) of 2388 RIU-1 are obtained for the proposed hybrid P-PhC sensor. These values are highest compared to the purely plasmonic and or purely PhC sensors reported in the literature. The proposed sensor could simultaneously enhance sensitivity and FoM values. Therefore, the proposed hybrid P-PhC RI sensor is a more fascinating candidate for high-sensitivity and high-resolution sensing applications at optic communication wavelengths.

Low loss hybrid plasmonic photonic crystal waveguide for optical communication applications

In this paper, a new design of hybrid plasmonic photonic crystal (PhC) waveguide is proposed and analyzed at operating wavelength of 1550 nm. The suggested design consists of hybrid cylindrical core with periodic grating as a cladding region. The effective index (neff), propagation length (Lp), and normalized mode effective area (Aeff) of the supported modes are numerically investigated using full vectorial finite element method. The cladding geometry is tuned to obtain long propagation length with good field confinement. The reported plasmonic PhC with uniform grating achieves long propagation length and low propagation loss of 124 µm, and 0.035 dB/µm respectively. Further, the PhC with chirped cladding offers propagation length and low propagation loss of 162 µm, and 0.0268 dB/µm at λ = 1550 nm, respectively.

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.

Modeling transmission light in photonic band gap of one-dimensional photonic-plasmonic crystals with buffer layer

The optical transmission wasn’t researched completely for the hybrid plasmonic-photonic crystal with buffer dielectric layer between photonic crystal (PC) and layer of gold. In this article we consider the dependence of wavelength of the Tamm plasmon on refraction index of the buffer layer. Wavelength of the transmission peak in the photonic band gap increases at the increasing refractive index of buffer layer between metal and PC. Intensity of the transmission peak in the photonic band gap decreases at the increasing refractive index of buffer layer in metal-PC interface. So we can change distribution of energy inside hybrid photonic-plasmonic mode. This results have a promise application in developing lasers and sensors.

Broadband self-collimating phenomenon in a low-loss hybrid plasmonic photonic crystal.

A 2D planar self-collimating photonic crystal, based on a dielectric square lattice and a hexagonal lattice, is proposed. We demonstrate that the proposed structure can support the propagation of a hybrid surface plasmon polarition (SPP) mode with a loss of -0.017 dB/μm, and the mode size is only 0.33μm. The defined figure of merit is one order of magnitude higher than that of the dielectric-metal structure. In addition, the self-collimating angle of more than 10° can be tuned with a silica index change of 0.08. The proposed structure possesses broad operation bandwidth of 88nm and 58nm for a dielectric square lattice and a hexagonal lattice, respectively. These two kinds of photonic crystals promise potential applications in photonic modulators and SPP photonic devices.

Transmission and reflection of self-assembled hybrid plasmonic-photonic crystals

We studied the optical properties of hybrid plasmonic-photonic crystals using spectral photometry. These structures consist of colloidal photonic crystal and gold layer deposited onto its surface. The samples of plasmonic-photonic crystals prepared with relatively simple method allow to observe different effects. Several peaks in the transmission spectra corresponding to the extraordinary transmission were investigated. The extraordinary transmission which depends on the angle of light incidence and polarization suggests the excitation of surface plasmon polaritons. An extraordinary reflection was also observed.

Topological phase transition and interface states in hybrid plasmonic-photonic systems

The geometric phase and topological property for one-dimensional hybrid plasmonic-photonic crystals consisting of a simple lattice of graphene sheets are investigated systematically. For transverse magnetic waves, both plasmonic and photonic modes exist in the momentum space. The accidental degeneracy point of these two kinds of modes is identified to be a diabolic point accompanied with a topological phase transition. For a closed loop around this degeneracy point, the Berry phase is π as a consequence of the discontinuous jump of the geometric Zak phase. The wave impedance is calculated analytically for the semi-infinite system, and the corresponding topological interface states either start from or terminate at the degeneracy point. This type of localized interface state may find potential applications in manipulation of photon emission of quantum dots, optical sensing and enhancement of nonlinear effects, etc.

Hybrid plasmonic-photonic crystal formed on gel-immobilized colloidal crystal via solvent substitution

Gel-immobilized colloidal crystals were prepared to obtain hybrid plasmonic-photonic crystals, in which electric field enhancement to a greater extent than that due to localized surface plasmons (LSP) alone was expected due to coupling between LSP and the photonic band. Polystyrene colloidal crystals immobilized by the N-(hydroxymethyl)acrylamide gel were immersed in an aqueous dispersion of gold nanoparticles (AuNPs). Then, the gel-immobilized colloidal crystals were picked out and immersed in an ionic liquid mixture. The surfaces of the gel-immobilized colloidal crystals immersed in the AuNP dispersion were observed via scanning electron microscopy after this solvent substitution. The lattice spacing of the colloidal crystal varied as the composition of the ionic liquid mixture was changed. The composition was determined so that the photonic band gap wavelength coincided with the LSP wavelength. Further, the reflection spectra were measured. Thus, we successfully prepared a hybrid plasmonic-photonic crystal.

Lattice plasmons in dielectric nanoparticle arrays arranged on metal film

We propose a hybrid plasmonic photonic crystal consisting of a square array of dielectric nanoparticles arranged on a metal film with a gap inbetween. Simulations show that this plasmonic crystal supports lattice plasmon modes just like the metal nanoparticle array, exhibiting an extremely narrow and deep reflection dip. When interparticle spacing increases from 800 to 1000 nm, the full width at half the maximum of lattice plasmons decreases from 21 to 4 nm, and the lowest reflectance is close to zero. The resonant wavelength of this plasmonic crystal is highly sensitive to the local environment. It yields a sensitivity of 700 nm RIU−1 and a figure of merit of 33, which can be used in sensing of the refractive index.

Nanostructure for Hybrid Plasmonic–Photonic Crystal Formed on Gel-Immobilized Colloidal Crystal Observed by AFM after Drying

Abstract Aiming at fabrication of hybrid plasmonic–photonic crystals, gel-immobilized colloidal crystals made of a polystyrene colloidal suspension and an N-(hydroxymethyl)acrylamide-based gel were immersed into an aqueous dispersion of gold nanoparticles. Atomic force microscope (AFM) observations have been performed for the gel-immobilized colloidal crystals with gold nanoparticles deposited on their surfaces. In the present study, the diameter of a colloidal sphere was ca. 190 nm. The diameter of a gold nanoparticle was the same as in a preliminary study, ca. 40 nm. Various immersion times up to two hours were tested. Surface of a sample of 2 h immersion has been observed. Prior to the AFM observation, the sample was dried in a desiccator for 18 h. We have identified a face-centered cubic {111} structure of a colloidal crystal of nearly close packing. Nanoparticles isolated with one another have been observed on the surface of gel-immobilized crystal, which can be regarded as gold nanoparticles from their sizes.

Hybrid Plasmonic Photonic Crystal Cavity for Enhancing Emission from near-Surface Nitrogen Vacancy Centers in Diamond

Optical cavities create regions of high field intensity, which can be used for selective spectral enhancement of emitters such as the nitrogen vacancy center (NV) in diamond. This report discusses a hybrid metal–diamond photonic crystal cavity, which provides greater localization of the electric field than dielectric cavities and mitigates metal-related losses in existing plasmonic structures. We fabricated such hybrid structures using silver and single-crystal diamond and observed emission enhancement of NVs near the diamond surface. We measured a mode quality factor (Q) as high as 170 with a simulated mode volume of ∼0.1 (λ/n)3 and demonstrated its tunability. This cavity design and the associated fabrication approach specifically target enhancement of emission from near-surface NVs.

Polarization Rotator Based on Hybrid Plasmonic Photonic Crystal Fiber

A photonic crystal fiber polarization rotator (PR) is proposed based on a novel mechanism-mode interference by two hybrid waveguide modes, rather than adjusting optical property in the light-guided part. The proposed PR is achieved by introducing two defects and an ancillary Au nanowire into the background lattice, and under the optimized parameters, the PR can offer almost a 100% polarization conversion ratio in the wavelength of 1.55-μm band (~100-nm bandwidth), compact length ~162.7 μm, low modal insertion loss of ~1.2 dB, and high coupling efficiency over 0.92 for both TE and TM mode based on the numerical simulation result of the full-vector finite-element method.

Spontaneous emission modulation of colloidal quantum dots via efficient coupling with hybrid plasmonic photonic crystal.

The spontaneous emission of colloidal CdSe/ZnS quantum dots (CQDs) modified by the hybrid plasmonic-photonic crystal is reported in this paper. By using a spin coater, the spatial overlap between CQDs and the surface resonance modes in this quasi-2D crystal slab is achieved. In this case, the coupling efficiency of them is enhanced greatly and most excited CQDs radiate through the surface modes. Consequently, despite the low refractive index contrast of our hybrid structure, the directionality of spontaneous emission, increased radiative probability and narrowed full width at half maximum of emission peak are all clearly observed by our home-made microscopic angle-resolved spectroscopy and time-resolved photoluminescence system. Our results manifest that the quasi-2D hybrid plasmonic-photonic crystal is an ideal candidate to tailor the radiative properties of CdSe/ZnS CQDs, which might be significant for the applications of light emitting devices.

High Q factor propagating plasmon modes based on low-cost metals

A hybrid plasmonic–photonic crystal consisting of a low-cost metal (Al or Cu) covered by self-assembly polystyrene sub-micro sphere arrays is fabricated. The angle-resolved reflection spectra show the existence of propagating optical surface modes in the structure. Especially, under normal incidence, five surface modes can be observed clearly. With the help of theoretical calculation, the origin of surface resonance modes is confirmed. From both the experiment and simulation, the surface plasmon modes supported by this structure possess high Q factors, which are comparable with those of the modes based on noble metals. Moreover, with a dielectric layer deposited on the top of the structure, its potential application for surface plasma polariton sensors is proposed.

Optical properties of silicon nanocavity-coupled hybrid plasmonic–photonic crystals in the optical region

Hybrid plasmonic–photonic crystals (HPPCs) have attracted considerable attention due to the cooperative effects of unique plasmonic and photonic features of the plasmonic and photonic crystals. In this work, we fabricate a novel HPPC by intercalating amorphous silicon nanocavities (Si-NCs) between the corrugated metallic plasmonic crystal and the colloidal crystal (CC). Multiple intensified transmission bands are experimentally observed through enhanced optical field coupling of the plasmon modes localized at the metal layer to the eigen modes in the CC by strong electric response of Si-NCs. Significant transmission modifications of such a structure can be efficiently tailored by tuning the geometry of Si-NCs. Calculated transmission spectra also demonstrate these. Our findings might provide potential applications in light harvesting and optoelectronic detections.

Effect of dimensionality on the spectra of hybrid plasmonic-photonic crystals

Based on colloidal crystals of various dimensionality, hybrid metal-dielectric plasmonic-photonic heterocrystals have been prepared. It has been shown that the spectra of optical transmission of heterocrystals are mostly controlled by the sum of contributions of composing plasmonic and photonic crystals. At the same time, there are a number of phenomena caused by the mutual effect of heterostructure components, which lead to a deviation of observed optical properties from the linear superposition of responses of these crystals. In particular, it has been found that the anomalous transmission controlled by the plasmonic crystal decreases with increasing the dimensionality of the photonic crystal attached to it. At the same time, light reflection on a metallized surface changes light diffraction in photonic crystals and leads to Fabry-Perot oscillation amplification. It has been assumed that an intermediate layer is formed, in which Bloch modes of the photonic crystal and surface plasmon-polaritons of the plasmonic crystal are hybridized.

Far-field disentanglement of modes in hybrid plasmonic-photonic crystals by fluorescence nano-reporters

AbstractIn this paper, the resonance modes exhibited by a hybrid nanostructure have been disentangled in the far-field owing to narrow-band fluorescence nano-reporters. Hybrid plasmonic-photonic crystals were fabricated using large (457 nm) monodisperse polystyrene spheres self-assembled into 2D photonic crystals and subsequently coated by a 30 nm thick silver layer. Such structures exhibit a complex resonance pattern, which has been elucidated owing to numerical simulations and electric near-field patterns obtained with a scattering type scanning near-field optical microscope (s-SNOM). For the sake of disentangling the resonance modes of the hybrid structure in the far-field, different types of semiconductor quantum dots (QDs), acting as nano-reporters of the local interactions, were dispersed on top of distinct structures. Depending on the relative overlap of the emission spectrum of a particular type of QDs with the resonance features of the hybrid structure, we affect their emission rate in a unique way, as a consequence of the complex interaction occurring between the plasmo-photonic modes and the excitons. Such plasmonic structures appear to be particularly relevant for fluorescence-based sensing devices.

Spectral and Directional Reshaping of Fluorescence in Large Area Self-Assembled Plasmonic–Photonic Crystals

Spectral and directional reshaping of fluorescence from dye molecules embedded in self-assembled hybrid plasmonic-photonic crystals has been examined. The hybrid crystals comprise two-dimensional hexagonal arrays of dye-doped dielectric nanospheres, capped with silver semishells. Comparing the reshaped fluorescence spectra with measured transmission/reflection spectra and numerical calculations reveals that the spectral and directional reshaping of fluorescence is the result of its coupling to photonic crystal Bloch modes and to void plasmons localized inside the silver caps.

Highly ordered and gap controllable two-dimensional non-close-packed colloidal crystals and plasmonic–photonic crystals with enhanced optical transmission

We present a facile one-step co-self-assembly method for the fabrication of two-dimensional (2D) non-close-packed (ncp) colloidal crystals (CCs) using polystyrene (PS) colloidal spheres and tetraethylorthosilicate (TEOS) sol. The resultant 2D ncp CCs demonstrated long-range ordering at the centimeter-scale without cracks due to the addition of TEOS sol. The inter-particle gap of the ncp CCs can be easily controlled by varying the amount of TEOS sol added during the assembly process. The crack-free 2D CCs were employed to form hybrid plasmonic–photonic crystals by depositing a thin film of gold. Experimental and simulated transmission spectra of the hybrid plasmonic–photonic crystals were found to be in good agreement. This simple and low-cost method provides a platform for the fabrication of high-quality 2D ncp CCs and may facilitate the development of various applications of ncp CCs.

PLASMONIC‐PHOTONIC CRYSTALS: Hybrid Colloidal Plasmonic‐Photonic Crystals (Adv. Mater. 22–23/2011)

In hybrid plasmonic-photonic crystals the metal and dielectric components are spatially separated in order to preserve their individual properties, but positioned in close vicinity to each other to warrant their efficient interaction. This design approach broadens the functionality of hybrid materials by relying on different resonance mechanisms for light transfer and ensures wide tuneability of the optical properties. These topics are explored in the Review by Romanov et al. (p. 2515).