Search

In this paper, we aim to design an all-optical structure that can be employed as optical OR/AND logic gates. To do so, a nonlinear photonic crystal-based ring resonator will be designed whose resonant wavelength depends on the variation of optical intensity. Then, by adding some optical waveguides, the optical logic circuit structure will be obtained that can function as optical OR/AND logic gates. The maximum time delay for the proposed structure is about 1.5 ps. Total footprint of the proposed structure is about 372 mm2. The proposed structure has lower time delay, lower footprint and lower optical input power compared with previously proposed structures.

In this chapter we discuss optical properties of dual-periodic photonic (super-)structures. Conventional photonic crystal structures exhibit a periodic modulation of the dielectric constant in one, two or three spatial dimensions (Joannopoulos, 2008). In a dual-periodic structure, the dielectric constant is varied on two distinct scales a1,2 along the same direction(s). An example of such a variation is given by the expression

Authors gratefully acknowledge valuable contributions of their collaborators and colleagues N. Gaponik, A. Eychmueller, A.L. Rogach, M. Bardosova, C.M. Sotomayor Torres, D.N. Chigrin, V.G. Solovyev, R. Kian and R. Zentel.

In this thesis the preparation and characterization of opal-based photonic crystals are described with the aim to control the properties of internal light sources.

In this work we present the theoretical and experimental verification of complete phononic band gaps in the Yablonovite structure with additional spheres in a face-centered cubic arrangement. The Finite Difference Time Domain method was used in the calculations of band structure and transmission spectrum. Different spatial directions and different polarizations of the incident acoustic field were investigated numerically and experimentally. Phononic band gaps in the acoustic band structure and in the transmission spectrum were calculated for all the examined cases of spatial directions and polarizations. The complete band gaps of the theoretical findings were confirmed by experimental measurements of 3D-printed prototype samples. All results are in very good agreement and validate complete phononic band gaps in these structures.

In this paper, an ultra-compact 1 × 5 and 1 × 10 beam splitters operating in optical C-band signals were numerically investigated and optimized in triangular lattice PhC slab employing the FDTD simulations. The high performances of both beam-splitters were reached by altering the junction area of the beam-splitter structure using topology optimization. The results show that the beam is distributed almost equally with extremely efficient total transmissions of about 99.23% and 94.39% and low insertion losses of about 0.03 and 0.25dB for the 1 × 5 and 1 × 10 beam-splitters successively around the optical operating wavelength 1550 nm.

Simulation upshot of photonic crystal fiber (PCF) is lucidly divulged in this research to envisage photonic topological insulator which depicts as a new application of silicon photonics. The notion and proposition of present work manipulates with plane wave expansion method to realize the photonic current at surface of PCF rather than core region. Finally the current proposal asserts that photonic crystal fiber with apt structure and parameter can be a good candidate for photonic topological insulator application.

In this paper theoretical investigation of photonic crystal based force sensor is presented. Photonic crystal ring resonator design is optimized for the improvement of quality factor considering the fabrication feasibility. For the optimized configuration a high quality factor of 15500 is obtained and it is found that it remains constant over the desired force range. The minimum detectable force is found to be 9 nN for 0.1 nm wavelength resolution. A high sensitivity of 11 nm/N is obtained in the studied force range. (C) 2017 Elsevier GmbH. All rights reserved.

This study investigated both numerically and experimentally one-dimensional photonic crystals with periodic structures composed of Ge and ZnS. Numerical simulations indicated that the refractive index, physical thickness, reference wavelength, and periodicity have a great effect on the position and width of the photonic band gap. We fabricated three different thicknesses of structures within the range of 3–5 μm, with average reflectance values of 89.1%, 94.9%, and 87.9%; the corresponding emissivity values were 0.096, 0.079, and 0.143, respectively. The results indicated that the high reflectance or transmittance at any required wave band could be achieved by selecting suitable materials and structures.

This paper explores the transmission characteristics of superconducting quasi-periodic photonic crystal structure arranged in Thue-Morse and double-period sequences. We mainly focused on the cutoff frequency of transmittance spectra. The study shows that the cutoff frequency can be appreciably tuned by generation number of sequence, thicknesses of constituent layers and operating temperature. Shifting behaviour of cutoff frequency is in contrast with periodic structure on varying superconductor thickness and temperature whereas it shows opposite trend on changing the dielectric layer thickness. It is also observed that different quasi-periodic structures show distinct values of cutoff frequency and different transmission properties. This features allow to tune the cutoff frequency or band gap in the whole infrared frequency region.

In this paper, we introduce a realistic vein-type photonic crystal slab design that exhibits self-guiding phenomenon. Both the plane wave expansion method (PWE) and 2D FDTD calculations are used in the optimisation process. We also show that this simple photonic crystal structure can be used as a collimating beam combiner. The obtained results show that employment of self-guiding effects can make photonic crystals advantageous with respect to metamaterials for the development of new optical devices.

A theoretical approach for computing the photonic band structure of 1D graphene based photonic crystal (1DGPC) using the Fourier Modal method (FMM) is presented. It is based on the resolution of the Maxwell's equations and the Bloch theorem. In the model, the graphene sheet is considered as layer with atomic thickness characterized by a dielectric function, which is frequency dependent and has a non-zero imaginary part. This frequency dependency is given by the Drude dielectric function. Under these conditions, we show that within the framework of the FMM, it is possible to obtain a polynomial eigenvalue problem allowing the calculation of the band structure which reveals photonic band structures with photonic bandgaps. It is concluded that the existing photonic bandgaps are highly tunable by varying the graphene chemical potential. Furthermore, we explore the spatial field-structure of certain modes and show that the modes associated with the lower edges of the bandgaps can be considered as quasi-modes generated by a cavity formed by the graphene and the dielectric medium.

Using the Dirichlet-to-Neumann map method and generalization of this method, we have been able to calculate the photonic band structure of two-dimensional (2D) metallodielectric photonic crystals composed of metal-coated circular dielectric rods. The rods are embedded in an air background with a square array. We are interested in considering transverse electric (TE) mode of electromagnetic waves. The resulting band structures show the existence of photonic band gaps as well as some flat band regions. We theoretically study the effect of the dielectric constant and radius of the dielectric core on the photonic band structures. There are some interesting results compared to the case of solid metallic rods (without dielectric core) such as appearing the new photonic band gaps and a flat band region with the characteristic of cavity modes.

In this paper, we are going to propose and design an all optical half adder based on photonic crystal structures. For realizing the proposed structure, we will use two nonlinear resonant cavities inside a two-dimensional photonic crystal structure. Nonlinear resonant cavities will be created by replacing the ordinary rods via defect rod made of nonlinear material such as doped glass. Plane-wave expansion and finite difference time domain methods will be used for simulating the proposed structure. For the proposed structure, the maximum delay time is about 3 ps.

In this study, a photonic crystal ring resonator with a triangular lattice is used to design an optical filter. The proposed structure is able to filter the central wavelength of 1548 nm with a transmission coefficient of over 95%. Moreover, this structure has an ultra-high-quality factor (Q) of about 1290. With altering the features of the structure including the refractive index, the lattice constant and the radius of the rods in the resonator core, their effects on the central wavelength of the filter, transmission coefficient, quality factor and bandwidth are investigated. The plane wave expansion and finite-difference time-domain methods are used to extract photonic band gap and investigate the photonic behavior of the proposed structure, respectively.

The possibility of efficient second-harmonic generation in the optical range in a planar dielectric waveguide with the active region in the form of a one-dimensional photonic crystal has been theoretically shown. The true phase matching can be achieved by controlling wave dispersion in the photonic crystal. The dispersion equations for the photonic crystal and three-layer waveguide have been self-consistently solved. It is shown that the coherence length may exceed 10 mm.

In this paper, we study a photonic crystal fiber (PCF) with circular lattice and engineer linear and nonlinear parameters by varying the diameter of air-holes. It helps us obtain low and high zero dispersion wavelengths in the visible and nearinfrared regions. We numerically demonstrate that by launching 100 fs input pulses of 1, 2, and 5 kW peak powers with center wavelength of 532 nm from an unamplified Ti:sapphire laser into a 100 mm length of the engineered PCF, supercontinua as wide as 290, 440 and 830 nm can be obtained, respectively. The spectral broadening is due to the combined action of self-phase modulation, stimulated Raman scattering and parametric four-wave-mixing generation of the pump pulses. The third and the widest spectrum covers the entire visible range and a part of near infrared region making it a suitable source for both white light applications and optical coherence tomography to measure retinal oxygen metabolic response to systemic oxygenation.

A design of all-optical half-subtractor (AOHS) is presented based on two-dimensional (2-D) photonic crystal (PhC) waveguides without using optical amplifiers and nonlinear materials. It is an essential component of various photonic integrated circuits. The design of AOHS circuit is based on beam interference principle, using square lattice of Y-shaped and T-shaped waveguides with silicon dielectric rods in air substrate. It is validated through finite-difference time-domain and using MATLAB simulations.

A tunable single-polarization filter is designed by filling high index liquid into the silver-coated air holes of photonic crystal fiber and the polarization characteristics are analyzed utilizing the finite element method. Results show that the filter can be used to realize, to our best knowledge, the filtering of an incoming signal at 1310 and 1550 nm bands simultaneously in two orthogonal polarization states with narrowband of full width half maximum only 9 nm (at 1550 nm bands). The confinement losses of unwanted polarized mode can reach up to 53.1 and 305.1 dB/cm at the two aforementioned communication windows, with other polarized mode losses as low as 0.8 and 2.4 dB/cm, respectively. For a propagation distance of 1 mm, the crosstalk of x - or y -polarized ( x - or y -pol) mode can reach a value of 45.4 and –262.9 dB at 1310 and 1550 nm bands, and the 20 dB bandwidth at 62 and 133 nm. By adjusting the silver-coated air hole diameter, the silver layer thickness, or the filling liquid, the filtering wavelength can be precisely tuned in a broad band range, from 1351 to 1931 nm of x -pol and from 1208 to 1392 nm of y -pol, covering almost all the communication wavelength.

In this paper, photonic crystal ring resonators with hexagonal lattice structure are used to design a four-channel optical demultiplexer. The structure size, the average transfer coefficient, the quality factor, and the channel spacing are equal to 424.5 µm2, 95.8%, 1943, and 2 nm, respectively. The average crosstalk is also computed to be −18.11 dB. In this study, the plane wave expansion (PWE) and finite-difference time-domain (FDTD) methods are used, respectively, to characterize the photonic bandgap and to investigate the optical behavior of the structure. The proposed design can be used in dense wavelength division multiplexing (DWDM) systems.

The theory of Smith-Purcell effect for a 2D photonic crystal is constructed from the first principles proceeding from Maxwell’s equations and microscopic characteristics of particles the crystal consists of. Two-dimensionality 2D is thought in two ways: i) the photonic crystal is an arranged system of particles disposed in a monolayer, ii) the periodicity is in two different directions. We derive the expression for the spectral and angular distribution of arising Smith-Purcell radiation. We analyse the features distinctive for the 2D photonic crystal and show that its spatial distribution differs drastically from the distribution of the radiation from conventional diffraction gratings.

An optical interference holographic setup with a symmetry-lost five or four-beam configuration is used to obtain two-dimensional special photonic crystals. By altering beam configuration and polarization combinations, novel structures can be achieved, such as tai chi-like, tadpole-like, and flag-like patterns. The experimental results with SU8 photoresist are the same with simulation. Process of two-dimensional special photonic crystals could provide an effective guidance for experimental design and fabrication of other complex structures, and thereby, promote the development and applications of novel photonic crystals.

The absorption in graphene is rather low at terahertz frequencies. Here, we present a graphene-embedded photonic crystal structure to realize broadband terahertz absorption in graphene. The approach provides absorption enhancement in the whole terahertz regime (from 0.1 to 10 THz). It is shown that the average absorption in the graphene-embedded photonic crystal can be enhanced in the multiple propagating bands of the photonic crystals. The absorption efficiency can be further improved by optimizing the characteristic frequency, optical thickness ratio in a unit cell, and the angle of incidence on the photonic crystals. A maximum broadband absorption factor of 28.8% was achieved for fixed alternative dielectric materials. The graphene-embedded photonic crystal is promising for terahertz functional devices with broadband response.

The tunable two-dimensional photonic crystals band gap, absolute photonic band gap and semi-Dirac point are beneficial to designing the novel optical devices. In this paper, tunable photonic band gaps structure was realized by a new type two-dimensional function photonic crystals, which dielectric constants of medium columns are functions of space coordinates. However for the two-dimensional conventional photonic crystals the dielectric constant does not change with space coordinates. As the parameter adjustment, we found that the photonic band gaps structures are dielectric constant function coefficient, medium columns radius, dielectric constant function form period number and pump light intensity dependent, namely, the photonic band gaps position and width can be tuned. we also obtained absolute photonic band gaps and semi-Dirac point in the photonic band gaps structures of two-dimensional function photonic crystals. These results provide an important theoretical foundation for design novel optical devices.

The one dimensional dielectric-magnetic photonic crystals (PCs) are materials with periodically varying permittivity and periodically varying permeability along the same direction. These PCs offer more degrees of freedom in designing photonic crystals. Most dielectric-magnetic PCs are fabricated with only two layers in each repeating unit cell. However, more than two layers in each periods are phenomenologically richer. This article presents the generalized formulation for the computation of Bloch wavenumbers and photonic bands of multilayered dielectric-magnetic PC based on the transfer matrix method. The formulation is valid for the lossy and lossless constituent materials. The numerical results for a dielectric only, magnetic only, and a dielectric-magnetic PC are also presented and discussed for the axial as well as oblique propagation.

A compact design of all-optical diode with mode conversion function based on a two-dimensional photonic crystal waveguide and an L1 or L3 cavity is theoretically investigated. The proposed photonic crystal structures comprise a triangular arrangement of air holes embedded in a silicon substrate. Asymmetric light propagation is achieved via the spatial mode match/mismatch in the coupling region. The simulations show that at each cavity’s resonance frequency, the transmission efficiency of the structure with the L1 and L3 cavities reach 79% and 73%, while the corresponding unidirectionalities are 46 and 37 dB, respectively. The functional frequency can be controlled by simply adjusting the radii of specific air holes in the L1 and L3 cavities. The proposed structure can be used as a frequency filter, a beam splitter and has potential applications in all-optical integrated circuits.

The theoretical and experimental investigations of photonic band gaps in one-dimensional photonic crystals created by micromatchining silicon, which have been performed by the author as part of his doctoral dissertation, are presented. The most important result of the work is the development of a method of modeling photonic crystals based on photonic band gap maps plotted in structure–property coordinates, which can be used with any optical materials and in any region of electromagnetic radiation, and also for nonperiodic structures. This method made it possible to realize the targeted control of the optical contrast of photonic crystals and to predict the optical properties of optical heterostructures and three-component and composite photonic crystals. The theoretical findings were experimentally implemented using methods of micromatchining silicon, which can be incorporated into modern technological lines for the production of microchips. In the IR spectra of a designed and a fabricated optical heterostructure (a composite photonic crystal), extended bands with high reflectivities were obtained. In a Si-based three-component photonic crystal, broad transmission bands and photonic band gaps in the middle IR region have been predicted and experimentally demonstrated for the first time. Si–liquid crystal periodic structures with electric-field tunable photonic band-gap edges have been investigated. The one-dimensional photonic crystals developed based on micromatchining silicon can serve as a basis for creating components of optical processors, as well as highly sensitive chemical and biological sensors in a wide region of the IR spectrum (from 1 to 20 μm) for lab-on-a-chip applications.

In this article, we propose a design of one dimensional cylindrical photonic crystal (CPC) that is composed of SiO 2 and Si alternating cylindrical layers. The optical properties of the CPC are investigated using the transfer matrix method in the cylindrical coordinate. Numerical results show that the suggested structures possess a photonic band gap in the optical frequency range. For high azimuthal mode number, m > 5, the photonic gap is greatly enhanced and it is robust for both transverse electric and magnetic polarizations. The proposed structure is a good candidate for applications including optical guidance, fiber optics communications among other potential applications.

This paper introduces optical multiplexer and demultiplexer (MUX/DEMUX) using 3-D photonic crystal (3-D PCs) structure around the wavelength of 1310 nm. Here 3-D PCs deals with the wavelength of 1306 nm–1311 nm using photonic bandgap analysis, where bandgap analysis is made by employing planewave expansion (PWE) technique. Simulation result divulges that both nature of background and configuration of structures play a significant role to envisage the design of optical multliplexer and demultiplexer. Again, it is reveled that allowed and disallowed wavelengths depend on structure parameters of 3D photonic crystal with nature of substrate. Aside this, it is found an interesting variation exist between allowed wavelengths with respect to both diameter of air holes and lattice spacing of the structure.

We calculate optical properties of guided modes of a hybrid-guiding photonic crystal fiber. The design and modeling of such hybrid-guiding PCF is made by replacing air holes with inserts of high refractive index material layer by layer in order. The optical properties such as mode intensity profile, mode dispersion, optical birefringence, confinement loss, and chromatic dispersion during transition of the guiding mechanism are analyzed and discussed. The guided modes in the hybrid-guiding region are also compared with those of reference index-guiding and bandgap-guiding photonic crystal fibers.

We theoretically investigate the dispersion and polarization properties of the electromagnetic waves in a multi-layered structure composed of a magneto-optic waveguide on dielectric substrate covered by one-dimensional dielectric photonic crystal. The numerical analysis of such a complex structure shows polarization filtration of TE- and TM-modes depending on geometrical parameters of the waveguide and photonic crystal. We consider different regimes of the modes propagation inside such a structure: when guiding modes propagate inside the magnetic film and decay in the photonic crystal; when they propagate in both magnetic film and photonic crystal., Comment: 12 pages, 9 figures, cofinanced from European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie GA No. 644348

Holographic lithography has been widely used to the realisation of complex photonic structures such as photonic crystal and quasi-photonic crystals. Dual-beam multi-exposure holographic technique was adopted for the fabrication of 18-fold and 36-fold sub-microscopic rotational symmetric structures; the fabricated photonic quasi-crystals examined by laser diffraction pattern, optical and scanning electron microscopes. Here, the authors have fabricated photonic quasi-crystals in photoresist and the structure was transformed into metal, the transferred structure in metal could act as a substrate/or back reflector for the thin film solar cell. Further work on concentration of solar light by photonic quasi-crystals is progressing.

In this study, we analyze complete photonic band gap properties of two-dimensional dielectric-plasma photonic crystals with triangular and square lattices, composed of plasma rods with different geometrical shapes in the anisotropic tellurium background. Using the finite-difference time-domain method we discuss the maximization of the complete photonic band gap width as a function of plasma frequency and plasma rods parameters with different shapes and orientations. The numerical results demonstrate that our proposed structures represent significantly wide complete photonic band gaps in comparison to previously studied dielectric-plasma photonic crystals.

A line-defect waveguide in a triangular lattice photonic crystal (PC) made of air holes in dielectric is demonstrated to support transverse magnetic (TM) as well as transverse electric (TE) guided modes simultaneously. A group of suitable geometric parameters were found to make the guided bands overlapped by means of Genetic Algorithm. The optimized waveguide realizes a polarization-independent single-mode transmission and wide operating bandwidth which reaches 0.012 Δ ω a / ( 2 π c ) . Moreover, the guided modes are shown to exhibit a wide-bandwidth slow light and an extremely low group velocity dispersion in most frequency range.

The spectral beam combination using bandgap analysis of photonic crystal structure at wavelength 1310 nm and 1550 nm is thoroughly investigated. Here photonic crystal structure is realized by three layers of alternative silicon (1st and 3rd layer) and air (2nd layer) material. The absorption losses in these materials are zero at aforementioned wavelengths. Simulation result revealed that structural parameters such as refractive indices and thickness of odd and even layer play an important role to find out spectral beam combining application. For examples; photonic crystal structure having thickness 500 nm of odd and even layers reflects both 1310 nm and 1550 nm wavelength. Similarly photonic crystal structure having thickness, 750 nm of odd and 250 nm of even layer reflects 1310 nm and transmits 1550 nm wavelength of light. Also, photonic crystal structure having thickness 850 nm of odd and 150 nm of even layer reflects 1550 nm and transmits 1310 nm wavelength of light. And photonic crystal structure having thickness 980 nm of odd and 20 nm of even layers transmits both 1310 nm and 1550 nm wavelength of light.

In this work, a phononic metamaterial that could be applied for both acoustic and elastic wave attenuation is numerically examined. The hollow yablonovite structure with the addition of hollow spheres on a face-centered cubic arrangement is examined numerically, and wide bandgaps are found for the propagation of acoustic and elastic waves. The calculations were performed by using the finite element method. The research includes an investigation of all the geometric parameters of the structure and how the bandgaps are being affected from the values of each parameter. The proposed structure is found to have wide bandgaps for both elastic and acoustic waves. These findings strongly indicate that the proposed acoustoelastic metamaterial is a powerful candidate for several applications such as sound and vibrations attenuation, noise reduction, and acoustic filtering.

In this research, we attempt to envisage the mirror application using semiconductor photonic crystal with the help of photonic bandgap analysis. The photonic bandgap of photonic crystal structure is simulated using plane wave expansion method, where photonic crystal is realized by 2D triangular photonic crystal structure with gallium arsenide as background material having periodic air holes. Simulation result revealed that both lattice spacing of crystal structure and radius of air holes play vital role in realizing optical mirror. It is observed that photonic band gap of the above structure is found, if radius of air hole varies from 16 nm to 50 nm for lattice constant of 100 nm . It is also seen that photonic band gap is found if lattice spacing varies from 200 nm to 650 nm for radius of air hole of 100 nm.

In this work, we use the plane wave expansion method to calculate photonic band structures in two-dimensional photonic crystals which consist of high-temperature superconducting hollow rods arranged in a triangular lattice. The variation of the photonic band structure with respect to both, the inner radius and the system temperature, is studied, taking into account temperatures below the critical temperature of the superconductor in the low frequencies regime and assuming E polarization of the incident light. Permittivity contrast and nontrivial geometry of the hollow rods lead to the appearance of new band gaps as compared with the case of solid cylinders. Such band gaps can be modulated by means of the inner radius and system temperature.

We review three types of light propagation mechanisms, like total internal reflection, photonic band gap guidance and Dirac mode guidance in hollow core photonic crystal fibers. Optimization techniques of structural parameters to obtain light propagation at desired wavelength of operation are presented. Surface Plasmon polariton modes generated on the gold wire placed in the photonic crystal cladding resonantly couple with the core guided mode. A highly sensitive refractive index sensor based on surface Plasmon resonance can be realized using plasmonic hollow core photonic crystal fiber. This study provides a great deal of designing knowledge based on numerical simulations which may be important to realize cutting edge technologies employing specialty hollow core photonic crystal fiber.

A 4-channel wavelength division demultiplexer based on photonic crystal ring resonators suitable for WDM applications is proposed in this paper. For performing the demultiplexing task, we used four resonant rings with different geometrical parameters. A square lattice of two dimensional photonic crystal structure composed of dielectric rods was used as fundamental structure for designing the demultiplexer, which has two photonic band gap regions. The first band gap covers the optical communication wavelengths. For this demultiplexer, the minimum transmission efficiency is more than 92% and average channel spacing is 3.2 nm.