2D Photonic Crystals Research Articles

Sensor with enhanced performance based on photonic crystal with a defect layer

We propose an improved structure of an optical biosensor based on a photonic crystal with a defect layer, which can detect the concentration of organic contaminants in water by defect mode shift. We investigated 4 types of defective photonic crystals with different arrangements of layers inside the perfect photonic crystals and their impact on the performance of the sensor. The sensitivity and amplitude of defect mode were examined as a function of defect layer thickness. Also, the peculiarities of edge modes in the presence of defect layer were investigated. Finally, we obtained a characteristic equation to determine the wavelengths of defect modes for an arbitrary 1D photonic crystal with an isotropic defect inside.

Design and analysis of a two-dimensional photonic crystal plus-shaped resonator for the detection of different cancerous cells and urine glucose

In this paper, a simple two-dimensional (2D) photonic crystal (PhC) plus-shaped resonator is suggested to detect different cancer cells as well as urine glucose. A novel biosensor design is presented that features a plus-shaped PhC resonator capable of detecting cancerous cells in human skin, cervix, blood, adrenal glands and breast, as well as detecting glucose levels in human urine to diagnose the likelihood of diabetes. Our biosensor boasts of an impressive quality factor of 307 for cancerous skin cells and 670.6 for glucose concentration in the blood. In addition, the device offers a maximum sensitivity of 750[Formula: see text]nm/RIU for detecting various cancerous cells and 2420[Formula: see text]nm/RIU for glucose in human urine. By positioning the resonator and the waveguide in a way that enables light to resonate in the middle of the structure and pass to the output terminal, we were able to focus on the absorption rate rather than the transmission. As a result, the maximum glucose and cancerous cell absorption rates reach 87.1% and 89.8%, respectively. Our unique yet simple sensor structure offers exciting new possibilities for detecting different cancerous cells and glucose concentrations, while the impressive sensitivity and quality factor make it an exceptional candidate for a wide range of biosensing applications.

Simulation and fabrication of ZnO/SiO2-based 1D Photonic crystals for light trapping application

Simulation and fabrication of ZnO/SiO2-based 1D Photonic crystals for light trapping application

Mode division (de)multiplexer based on transverse mode conversion in photonic crystal using asymmetric directional couplers.

Mode division multiplexing technology has the potential to increase the channel capacity of a single wavelength carrier. Attaining cost-effective high-bandwidth-density devices with small footprints is a concern, and photonic crystal based devices are promising for ultra-small on-chip communications. This paper presents a 2D photonic crystal based mode division (de)multiplexer on a silicon on insulator platform. The device comprises two coupling regions of asymmetric directional couplers that perform mode conversion operations between the fundamental mode and higher-order modes. Each coupling section is dedicated to converting a specific mode. Mode conversion is achieved by designing a multimode waveguide to satisfy the phase-matching condition of the desired mode with the single mode waveguide. Two linear adiabatic tapers are introduced for the smooth transition of modes between waveguide sections. The device is designed and simulated for three-channel modes at 1550nm using the finite-difference time-domain technique. The obtained insertion loss and cross talk are <0.41d B and <-20.14d B, respectively. The overall size of the proposed mode division (de)multiplexer is 328.5µm 2. A fabrication tolerance study for the proposed device is performed by varying the rod radius and position in the device structure's taper and bus waveguide regions. The proposed 2D photonic crystal based mode division (de)multiplexer has the potential to be used in large-capacity optical communication systems.

High performance of photonics crystals Demux with an integrated channel drop filter based on annular periodic ring cavity

Abstract In this work, we are interested in the design of a basic filter structure based on an annular ring cavity where we study its characteristics and its performance in terms of transmission and selectivity of the signal. The basic structure is a 2D photonic crystal (PC) with holes in the substrate which are more suitable for different PC manufacturing processes. Based on the optimization of the filter structure results, we created a high performance structure and improved a 4 channels demultiplexer (DEMUX) with an optical parameters which are the transmission efficiency, the quality factor and the crosstalk with average values of 97.25, 3171 and −26.58 dB, respectively, it had a significant role in optical communication networks. The compact size of the proposed DEMUX is 211.7 μm2 which is suitable for the integrated optics. To determine the photonic band gap (PBG) of our proposed structure, we used the plane wave expansion (PWE) method and the finite difference time domain (FDTD) method used to study normalized transmission.

Ultra-trace chlorinated gases optical sensor with moisture-resistant based on structural-customizable UiO-66 3D photonic crystals

Chlorinated gases seriously pollute the environment and threaten human health. Limitation of insufficient adsorption sites and interference of atmospheric humidity, designing an advanced sensing device with high adsorption and moisture resistance is still a challenge to detect chlorinated gases for air monitoring. Herein, a moisture-resistant optical sensor based UiO-66 three-dimensional (3D) photonic crystals is achieved. The optical sensor shows customizable structure and tunable optical properties, which are benefit to gas diffusion and signal transduction. The application of the optical sensor for 2.5 ppm carbon tetrachloride (CCl4), dichloromethane (CH2Cl2), chlorobenzene (C6H5Cl) and hydrochloric acid (HCl) detection was investigated in relative humidity (RH) 35%. The sensor exhibits excellent selectivity for HCl, which agree with the density functional theory (DFT) calculations for the adsorption energy. Especially, the sensor exhibits high stability and repeatability under RH 50%− 95%, and the sensing performance of the sensor for 2.5 ppm HCl has improved at RH up to 65%, limit of detection (LOD) can reach 10.9 ppb, ultra-fast response was 0.49 s. The improvements in sensing performance under RH are attributed to moisture-enhanced adsorption mechanism. This work provides a new insight for effective utilization of advanced materials and device to achieve ultra-trace chlorinated gas detection in humid atmosphere.

All-optical half-adder in a linear three-core fiberdevice.

The half-adder is one of the most useful combinational logic functions for data processing. Many research papers in the literature propose nonlinear all-optical half-adders. Few studies propose linear all-optical devices, and those that do usually employ microstructured 2D photonic crystals. This work presents the numerical acquisition of an all-optical half-adder using a linear three-core fiber device. The device presents high performance and acceptable values of fabrication and modulation tolerance. It can be made using any fiber technology and propagated by pulses of any wavelength. Depending on the type of fiber used, the precision needed to fabricate the device's smallest structures can range from 20nm to 90nm. This result is evidence of the possibility of obtaining nonlinear logical processing using only fiber design.

Smith–Purcell radiation controlled by the transmission characteristics and quality factor of a layer

Photonic crystal structures have attracted significant attention because of their ability to confine light, especially outgoing waves in a bandgap. In this study, we investigate a layer that can control the Smith–Purcell radiation. The results show that transmission characteristics and quality factor of a 1D photonic crystal can narrow the radiation spectrum and enhance the radiation intensity. From another perspective, the entire structure can be treated as a composite grating, the radiation spectra of which are obtained by theoretical calculations and agree with that from the analysis based on the role of the 1D photonic crystal. Therefore, it can be concluded that the radiation from a composited structure can be simplified by the radiation controlled by the 1D metal photonic crystal, and it provides a fast way to reshape the radiation spectra by designing the transmission characteristic and quality factor of the photonic crystal. Furthermore, a layer with special transmission characteristics and quality factor above a reflection grating can be used to achieve coherent and tunable Smith–Purcell radiation, which is significant for the development of band-controllable light or terahertz radiation sources.

Incident-side-dependent mirror based on 1D photonic crystals containing VO2 nanoparticles

The optical properties of an incident-side-dependent mirror based on a one-dimensional photonic crystal composed of nanocomposite layers containing vanadium dioxide nanoparticles were investigated theoretically using the transfer matrix method in the near-infrared spectral range. The influence of the incident angle and filling fraction of the vanadium dioxide nanoparticles on the reflectance and transmittance of the structure were studied. We found that the mirror is an incident-side-dependent reflector with nearly zero transmittance in the photonic bandgap regions. The incident-side-dependent properties of the mirror are more pronounced when the vanadium dioxide nanoparticles are in their metal phase. In addition, the mirror is a perfect reflector for incoming rays from one side and a perfect absorber for incoming rays from the opposite side. Such temperature-controlled and incident-dependent mirrors may find application in the design of various intelligent windows.

Pixelated Photonic Crystals

Photonic crystals can prevent or allow light of certain frequencies to propagate in distinct directions in anomalous and useful ways for use as waveguides, laser cavities, and topological light propagation. However, there exist limited approaches for fundamental reconfiguration of photonic crystals, such as changing the unit cell to various and on‐demand geometries and symmetries. This work introduces the concept of pixelated 2D photonic crystals where the variability of the dielectric profile is achieved by a pixelated matrix of the material. Specifically, the cross sections of dielectric cylindrical pillars distributed in a photonic crystal lattice are replaced with pixelated circles using different resolutions and the corresponding band diagrams are calculated. The comparison to the band diagrams of the original structure shows that the original—and today typically used—cylindrical design can be well approximated by as few as square switchable pixels while retaining less than change in the photonic band structure. Experimental realization of switchable pixelation is proposed based on the liquid crystal display (LCD) technology with high birefringence materials. More generally, the demonstrated approach to reconfigurable 2D photonic crystal based on switchable pixels can enable realization of diverse fundamentally reconfigurable advanced optical materials.

Angle-insensitive topological interface states in hybrid one-dimensional photonic crystal heterostructures containing all-dielectric metamaterials.

Topological interface states (TISs) in conventional one-dimensional (1D) photonic crystal (PhC) heterostructures strongly shift toward higher frequencies as the incident angle increases. This strong blueshift property of TISs intensively limits the operating angle ranges of TISs. Herein, we design two angle-insensitive photonic bandgaps (PBGs) in two hybrid 1D PhCs containing all-dielectric metamaterials. By cascading these two hybrid 1D PhCs to construct a hybrid 1D PhC heterostructure, we achieve an angle-insensitive TIS under transverse magnetic polarization. Empowered by the angle-insensitive property of the PBGs, the angular tolerance of the TIS reaches 69.65°, which is much higher than those of the TISs in conventional 1D PhC heterostructures. In addition, the angle-insensitive property of the TIS is robust against the layer thickness. Our work provides a viable route to achieving TISs with high angular tolerances and would facilitate the applications of photonic topological states.

Dual-responsive photonic multilayers in combination with a smartphone application as high-security anti-counterfeiting devices

A new concept for dual-responsive one-dimensional (1D) photonic crystal (PC) multilayers is proposed herein. The novel PC-based systems rely on the humidity from the human breath and fluorescence triggered by Al3+ coordination to act as high-security anti-counterfeiting labels to be used in combination with a smartphone application. The dual-responsive patterned film is fabricated via the alternating deposition of photo-crosslinkable poly(2-vinylnaphthalene-co-benzophenone acrylate) and 51%-quaternized poly(4-vinylpyridine-co-benzophenone acrylate) onto a transparent polyethylene terephthalate substrate to obtain 1D PC multilayers, followed by the introduction of a poly([(2-hydroxybenzylidene)-4-vinylbenzohydrazide-co-benzophenonyl acrylate) top coating. The obtained system is then exposed to ultraviolet light irradiation through variously patterned masks. The patterned films exhibit vivid dual color transitions in high-humidity environments along with remarkable turn-on fluorescence, following the coordination of Al3+ ions upon spraying with a 1 wt% Al(NO3)3 solution. Notably, the efficacy of the combination between the two-step security function of the flexible patterned multilayer films and a smartphone app was also demonstrated. The first level of security involves the determination of the RGB color value before and after a color change triggered by blowing onto the film. The second level of security involves the revelation of hidden fluorescent shapes under ultraviolet light irradiation after Al(NO3)3 spraying.

Tuning the Luminescence Response of an Air-Hole Photonic Crystal Slab Using Etching Depth Variation.

Detailed studies of the luminescent properties of the Si-based 2D photonic crystal (PhC) slabs with air holes of various depths are reported. Ge self-assembled quantum dots served as an internal light source. It was obtained that changing the air hole depth is a powerful tool which allows tuning of the optical properties of the PhC. It was shown that increasing the depth of the holes in the PhC has complex influences on its overall photoluminescence (PL) response due to the simultaneous influences of counteracting factors. As a result, the maximal increase in the PL signal of more than two orders of magnitude was obtained for some intermediate, but not full, depth of the PhC's air holes. It was demonstrated that it is possible to engineer the PhC band structure in such a way as to construct specific states, namely bound states in continuum (BIC), with specially designed dispersion curves being relatively flat. In this case, such states manifest themselves as sharp peaks in the PL spectra, and have high Q-factors which are larger than those of radiative modes and other BIC modes without such a flat dispersion characteristic.

Defect mode properties of self-similar symmetry order in triadic Cantor photonic crystals

The discovery of quasi-crystal tells us that not only the translational symmetry order (TSO) but also other orders can produce Bragg diffraction. As far as we know, in one dimensional (1D) photonic crystals (PCs) there are two symmetry orders, TSO and self-similar symmetry order (SSO). There has been a lot of researches exploring the properties of defect of TSO in the 1D PCs, but until now we do not find any studies related to the defect of SSO. In this work we consider the triadic Cantor set (TCS) PCs to stage 6, and attempt to create the defect of SSO by changing the scale factor of stage 2 to 3 and stage 3 to 4, where for the high-refractive-index layer only the thickness of stage 3 changes. It's well known that the defect of TSO governs the frequency of a kind of transmission peaks, called defect mode. Our results show that the defect of SSO influences the background intensity of the transmittance spectrum rather than the transmission peaks. We note that the defect mode frequency and the transmittance background intensity interchange their roles for the two symmetry orders, and it follows that the long neglected transmittance background intensity should be a significant optical property.

Design and performance analysis of eight channel demultiplexer using 2D photonic crystal with trapezium cavity

In this work, an eight-channel dense wavelength division multiplexing demultiplexer is designed with a 2D photonic crystal triangular lattice. The proposed demultiplexer consists of a centre bus waveguide, an isosceles trapezium resonant cavity, and an eight-circular ring cavity (CR1, CR2, CR3, CR4, CR5, CR6, CR7, and CR8). The point defect resonant cavity consists of seven rods to drop different wavelengths from eight cavities, each of eight drop waveguides. The design is very simple to realise. The finite difference time domain and plane wave expansion method methods were used to analyse the proposed design’s band structure and transmission spectrum. The resonant wavelengths are 1.5441 μm, 1.5443 μm, 1.544 49 μm, 1.5447 μm, 1.5449 μm, 1.5451 μm, 1.5453 μm, and 1.5455 μm respectively. The proposed device provides a high-quality factor, transmission efficiency, and low crosstalk. The device’s footprint is 490.0 μm2, which can be easily incorporated into photonic integrated circuits.

Near-perfect wide-band absorbers based onone-dimensional photonic crystal structures in1-20 THz frequencies.

This paper investigates the absorption behavior of one-dimensional (1D) photonic crystal (PhC) structures in the 1-20THz region. The structures are analyzed by the transfer matrix method to achieve accurate results quickly with ordinary simulation facilities. The simulation results indicate a strong dependence of the absorber performance on the thickness and material of the PhC layers, as well as the frequency and angle of incident light. The combination of silica and titanium (Ti) materials as dielectric and metal layers presents a great choice for broadband high-absorption applications so that this structure can absorb, on average, more than 80% of the normal incident radiation in the studied frequency range. Additionally, this absorber has the lowest dependence on incident light with the angle varying from 0° to 80° compared to identical absorbers with silver, aluminum, gold, chromium, nickel, and tungsten metals. The excellent absorption feature of the Ti-based absorber compared to the other absorbers is attributed to the lower permittivity of Ti (in both real and imaginary parts) in comparison with the other metals. In addition to owning simple and fabrication-friendly structures, 1D PhCs can pave the way to achieve various absorption spectra proportional to the needs of photonics, communications, and aerospace applications.

Comparative investigation of 1D photonic crystal of magneto-optical and electro-optical materials with a nanocomposite of three/four-phase mixtures

Comparative investigation of 1D photonic crystal of magneto-optical and electro-optical materials with a nanocomposite of three/four-phase mixtures

Deep Learning-based Inverse Design of the Complete Photonic Band Gap in Two-Dimensional Photonic Crystals

Background: With the continuous development of computer science, data-driven computing methods have shown their advantages in various fields. In the field of photonics, deep learning (DL) can be used to inversely design the structure of optical devices. Objective: The two-dimensional (2D) photonic crystal (PCs) with adjustable structural parameters and a large complete photonic band gap (CPBG) are inversely designed in terms of DL neural network (NN) tagged to obtain a specified width of CPBG. Methods: The new PCs structure is designed by combining multiple factors that produce a CPBG. Tandem networks are used to speed up the training of the NN and tackle the problem of nonuniqueness that arises in inverse design. Results: After various attempts and improvements, the ideal PCs structure was obtained. It is found that the connecting channel between the primitives in the PCs unit cell has a dominate effect on the CPBG. The use of a tandem network enables better convergence of the network. Finally, suitable NN can be obtained, which can realize the forward prediction of the CPBG and the inverse design of the structure. Conclusion: DL can realize forward prediction and inverse design of 2D PCs targeting the width of the CPBG, which broadens the application scope of DL in the field of PCs.

Rigorous Electrodynamic Analysis of a Cylindrical Lens Consisting of Hollow Perfectly Conductive Cylinders

A fast and rigorous method is developed for the electrodynamic analysis of an infinite cylindrical lens made of an artificial material, which is an array of hollow conducting cylinders of finite length and finite wall thickness, identically oriented along the lens axis. It is shown that the method makes it possible to calculate the characteristics of lenses consisting of multiple elements using a personal computer. The focusing properties of the lens are studied. The method is an alternative to and a technique to verify the approach based on the analysis of a lens made of a homogenized material with a refractive index of an infinite 3D photonic crystal.

Biophotonic sensor design for the detection of reproductive hormones in females by using a 1D defective annular photonic crystal

Abstract In this research work, we have proposed a one-dimensional (1D) defective annular photonic crystal (DAPC) (AB)5 CDC(AB)5 to identify the presence of reproductive progesterone and estradiol hormones in women. The periodicity of the proposed biosensing design made up of 1D annular photonic crystal (APC) has been broken by introducing a cylindrical cavity D of porous gallium nitride (GaN) material. The inner and outer faces of cylindrical cavity D are surrounded by concentric cylindrical buffer layers of magnesium fluoride (MgF2) material. We have used a modified transfer matrix method with the help of MATLAB software to carry out investigations pertaining to the proposed theoretical work. The two distinct categories of blood samples containing reproductive hormones of different concentrations have been used in this work. The sensitivity of proposed 1D DAPC varies between 159.673 nm nmol−1 L−1 to 170.1525 nm nmol−1 L−1 when a cavity is infiltrated with a blood sample having progesterone hormone whose concentration varies between 0 and 200 nmol L−1. Moreover, the sensitivity of the structure varies between 158.7816 nm nmol−1 L−1 to 170 nm nmol−1 L−1 under the influence of blood samples having estradiol hormones of different concentrations. In order to evaluate the performance of the proposed biosensor in the true sense we have also computed quality factor (Q) and figure of merit (FoM) values of the biosensor corresponding to both categories of blood samples of different concentrations. Our study shows that biosensors made up of 1D annular photonic structures are more efficient in comparison to the biosensors made up of planar 1D photonic crystals. Apart from detecting the reproductive hormones in females such kind of APC-based specialized biosensing devices may be very useful in the field of medical engineering and technology.