Dimensional Photonic Crystals Research Articles

A comparative study of photonic band gaps for different materials of one dimensional photonic crystals

A comparative study of photonic band gaps for different materials of one dimensional photonic crystals

Two types of corner states in two dimensional photonic crystals with finite sizes

Abstract Using two-dimensional (2D) square lattice photonic crystals (PCs) with different topological properties, we design different combined structures to construct two types of topological corner states (CSs), named as Type I and Type II CSs. Then by tuning sizes of inner PCs in the combined structures, we systematically investigate size effects on the two types of CSs. Numerical results demonstrate as the structures decrease to their critical sizes, due to the interactions of opposite interfaces and the couplings of corners, size changes of inner PCs in the combined structures have significant effects on the frequencies, degeneracies and mode field distributions of the two types of CSs. Moreover, Type I CSs peform better topological stability than Type II CSs during the size changes of structures. We also monitor mode field localizations of the two types of CSs and reveal that their localizations are only related to the types of the CSs, and have no relations to sizes and overall symmetries of the combined structures. Our research enriches the study of higher order topological CSs and paves the way for design and manufacture of optical micro-nano devices with photonic topological CSs.

A new proposal for low power 4 × 2 optical encoder using AND OR NOT mechanism in two dimensional photonic crystals

A new proposal for low power 4 × 2 optical encoder using AND OR NOT mechanism in two dimensional photonic crystals

Design of All-Optical D Flip Flop Memory Unit Based on Photonic Crystal.

This paper proposes a unique configuration for an all-optical D Flip Flop (D-FF) utilizing a quasi-square ring resonator (RR) and T-Splitter, as well as NOT and OR logic gates within a 2-dimensional square lattice photonic crystal (PC) structure. The components realizing the all-optical D-FF comprise of optical waveguides in a 2D square lattice PC of 45 × 23 silicon (Si) rods in a silica (SiO2) substrate. The utilization of these specific materials has facilitated the fabrication process of the design, diverging from alternative approaches that employ an air substrate, a method inherently unattainable in fabrication. The configuration underwent examination and simulation utilizing both plane-wave expansion (PWE) and finite-difference time-domain (FDTD) methodologies. The simulation outcomes demonstrate that the designed waveguides and RR effectively execute the operational principles of the D-FF by guiding light as intended. The suggested configuration holds promise as a logic block within all-optical arithmetic logic units (ALUs) designed for digital computing optical circuits. The design underwent optimization for operation within the C-band spectrum, particularly at 1550 nm. The outcomes reveal a distinct differentiation between logic states '1' and '0', enhancing robust decision-making on the receiver side and minimizing logic errors in the photonic decision circuit. The D-FF displays a contrast ratio (CR) of 4.77 dB, a stabilization time of 0.66 psec, and a footprint of 21 μm × 12 μm.

Square-root topological insulator for a dual-band photonic waveguide

We show that square-root topological insulators can be utilized as a platform for dual-band topological waveguides in 2-dimensional photonic crystals. Valley states for each of two frequency band gaps in differently perturbed decorated honeycomb lattices have opposite directions of the phase rotations, revealing opportunities for dual-band unidirectional topological valley transport. The topological valley edge states exist at the boundary between differently perturbed photonic crystals in the two frequency bands. In addition, unidirectional, and robust propagation of electromagnetic waves along the boundary in the two frequency bands are numerically performed. Our work provides extensions of square-root topological insulators to robust, unidirectional, and dual-band photonic waveguides.

Optimal design of multilayer optical thin film structure for smart energy saving applications using needle optimization approach

In this work, a novel design of a one dimensional photonic crystal (1D PC) is investigated. The 1DPC structure is composed of alternating layers of tantalum pentoxide (Ta2O5) and silicon dioxide (Sio2). The proposed 1D PC structure is designed to act as short wave pass (SWP) edge filter that selectively passes light of short wavelengths, while the infrared light is blocked. In this study, Essential Macleod software is used to create the optimal design with the computational support of the needle synthesis technique. By varying the incidence angle of the mean polarized light mode, we can determine the features of the optimal SWP edge filter design, which leads to an important application for this filter. It can shed light on the filter’s suitability as a smart energy saving window coating for hot climate regions. The study includes different hot regions in Saudi Arabia such as Mecca, Riyadh, Dammam, Arar and Alaqiq. They were used as case studies in this research. According to the study of the optimal design of SWP edge filter applied in Mecca, Riyadh, Dammam, Arar and Alaqiq provinces, the light transmittance in the visible region is more than 99% during the summer solstice and more than 96% during the winter solstice. The photonic band gab (PBG) is almost constant during the summer solstice without shifting or decreasing in size whereas in the winter solstice, the PBG shifts toward the short wavelengths and decreases in size by increasing the angle of incidence. This allows an amount of solar energy to enter in winter. Riyadh, Dammam, and Arar provinces experienced a significant increase in solar energy during the winter solstice, more than Mecca and Alaqiq provinces.

On the sensitivity of defect modes outside the first photonic bandgap in optical sensors based on defected 1D photonic crystals

In this paper, we investigated the possibility of using of defect modes (DMs) in the second photonic bandgap (PBG) in defective one dimensional (1D) photonic crystals (PCs) for creating optical sensors. The dependencies of the relative sensitivities on the defect layer (DL) thickness for the first and second PBGs at optimized PC parameters are obtained and compared and the advantage of the first PBG over the second PBG in all ranges of the DL thickness is shown. However, as the order of the defect mode (DM) and optical contrast of the structure increase, this relative advantage becomes less prominent. The behavior of the DMs and their relative sensitivity outside the PBG when DL thickness changes are considered. The dependences of the relative sensitivity on different parameters of the PC for DM in the first and second PBGs are also compared. This work is mainly theoretical and aims at finding general patterns that can be generalized to any specific examples and parameters of 1D PC with DL for any practical realizable sensors.

A 1064 nm laser adaptive limiter with visible light transparency based on one dimensional photonic crystals of LiNbO3 defects.

Herein, we present the investigation of the visible light transparency and optical limiting characteristics of one dimensional photonic crystals with LiNbO3 defects fabricated by the sputtering technique. Transmission spectroscopy measurements reveal a broad photonic band gap with a 1064 nm defect mode and high transmittance within the visible range. The optical energy limiting performance in the photonic crystal can be attributed to the strong confinement of the optical field surrounding the LiNbO3 defect layer. The low energy 1064 nm laser demonstrates a transmittance of 82.15%. Notably, the optical limiting threshold is lower at 62.03 mJ cm-2 in comparison with conventional optical limiting materials. Additionally, the optical limiter achieves a transmittance of 68.57% within the visible light band.

Ultra compact, high contrast ratio all optical NOR gate using two dimensional photonic crystals

An all-optical NOR gate is implemented using a two-dimensional photonic crystal waveguide. The paper provides a structure of an all-optical NOR gate constructed by introducing a line and point defect. The proposed NOR gate uses a hexagonal lattice structure with E shaped waveguide. The contrast ratio, response time and bit rate of three input NOR gate are 29.59 dB, 0.8 ps and 1.19 Tbps, respectively. The proposed gate is constructed with the operating wavelength of 1550 nm. The structure has been simulated and analyzed using Finite Difference Time Domain (FDTD) and Plane Wave Expansion (PWE) methods. It offers high contrast ratio, better response time with ultra-compact size. Hence it is suitable for high speed optical integrated circuits and switching devices.

Defect modes in defective one dimensional parity-time symmetric photonic crystal

The introduction of defect layers into one-dimensional parity-time (PT) symmetric photonic crystals gives rise to resonances within the photonic bandgaps. These resonances can be effectively explained by our generalized temporal coupled mode theory. The scattering properties and dispersion relation of defect modes exhibit distinct characteristics compared to conventional one-dimensional Hermitian photonic crystals with defect layers. By tuning the non-Hermiticity or other model parameters, the modulus of the generalized decay rate can be reduced, consequently, the electric field concentrated within the defect layer strengthens. This arises due to the unique band structure of one-dimensional PT-symmetric photonic crystals, which differs significantly from that of traditional one-dimensional Hermitian photonic crystals. Furthermore, the interaction between multiple resonances is investigated through the introduction of multiple defect layers. Our study not only provides insights into resonance phenomena in defective non-Hermitian systems but also contributes to the design of relevant optical resonance devices.

Biophotonic sensor for swift detection of malignant brain tissues by using nanocomposite YBa2Cu3O7/dielectric material as a 1D defective photonic crystal

In the present research work we have theoretically examined the biosensing capabilities of proposed one dimensional defective photonic crystal for swift detection of malignant brain tissues. The transfer matrix formulation and MATLAB computational tool have been used to examine the transmission properties of proposed structure. The identical buffer layers of nanocomposite superconducting material have been used either side of cavity region to enhance the interaction between incident light and different brain tissue samples poured into the cavity region. All the investigations have been carried out under normal incidence to suppress the experimental liabilities involved. We have investigated the biosensing performance of the proposed design by changing the values of two internal parameters (1) the cavity layer thickness (d4) and (2) volume fraction (η) of nanocomposite buffer layers one by one to get the optimum biosensing performance from the structure. It has been found that the sensitivity of the proposed design becomes 1.42607 μm/RIU when the cavity region of thickness 15dd is loaded with lymphoma brain tissue. This value of sensitivity can be further increased to 2.66136 μm/RIU with η = 0.8. The findings of this work are very beneficial for designing of various bio-sensing structures composed of nanocomposite materials of diversified biomedical applications.

The transport of dipole solitons in a one-dimensional nonlinear photonic crystal

Quadratic χ(2) nonlinearity crystal provide an ideal stage for the researches of the transport of optical solitons. However, the transport of dipole solitons in a homogeneous χ(2) nonlinear medium is unstable. To solve this problem, a one dimensional nonlinearity photonic crystal is designed from a χ(2) nonlinearity crystal by quasi-phase matching technique. The duty cycle of the positive polarized in the transverse direction of the crystal is periodic modulated, so as to realize a stable transport of dipole solitons in it. Besides, relations of the transportation characteristics of the dipole soliton and the modulation parameters are researched in this letter numerically. Moreover, mobility and collision of these dipole soliton through the crystals are discussed through the paper. Some key parameters of the related experiment are also estimated.

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.

Moisture-enhanced trace chloroalkanes detection in bimetallic metal-organic frameworks 3-dimensional photonic crystal.

Chloroalkanes have long been a threat to environmental protection and human health, however, rapid and efficient detection of chloroalkanes remains challenging. Herein, 3-dimensional photonics crystals (3-D PCs) based on bimetallic materials of institute lavoisier frameworks-127 (MIL-127, Fe2M, M=Fe, Ni, Co, Zn) demonstrate the great potential of chloroalkanes sensing. Particularly, at temperature of 25°C and dry conditions, the 3-D PC consisting of MIL-127 (Fe2Co) shows optimal selectivity and high concentration sensitivity of 0.0351±0.00007nmppm-1 to carbon tetra-chloride (CCl4), and the limit of detection (LOD) can reach 2.85±0.01ppm. Meanwhile, MIL-127 (Fe2Co) 3-D PC sensor presents a rapid response of 1s and recovery time of 4.5s for CCl4 vapor, and can maintain excellent sensing performance under heat-treatment of 200°C or in the long-term storage (30 days). Mechanism studies indicated that the excellent sensing property derived from the doping of transition metals. Moreover, the moisture-enhanced adsorption of CCl4 for the MIL-127 (Fe2Co) 3-D PC sensor is also observed. H2O molecule can remarkably enhance the adsorption of MIL-127 (Fe2Co) to CCl4. The MIL-127 (Fe2Co) 3-D PC sensor shows the highest concentration sensitivity of 0.146±0.00082nmppm-1 to CCl4 and the lowest limit of detection (LOD) of 685±4ppb under the pre-adsorption of 75ppm H2O. Our results provide an insight for a trace gas detection using metal-organic frameworks (MOFs) in the optical sensing field.

Design and simulation of reconfigurable optical logic gates for integrated optical circuits

The proposed work presents design and simulation of a new reconfigurable optical logic AND, NOT and NOR gate constructed in a two dimensional (2D) photonic crystals (PhCs). Due to many advantages like high speed, fast response, high bit rate and compact size these optical gates find applications in optical devices, communications and optical sensors for next generation optical systems. The proposed gate structures can be used in realization of all optical devices used in photonic integrated optical circuits. These optical logic gates are constructed in 6 µm * 6 µm in 2D PhCs square lattice structure with a lattice constant a = 0.648 µm. All the gates are realized by creating structural disorders in the cross-waveguide geometries of 2D PhCs. The plane wave expansion (PWE) is utilised to get the complete band gap and required band of the waveguide. Finite difference time domain (FDTD) technique is utilised to investigate the performance of these gates. The several performance parameters are examined using this structure and observed that proposed structure has reduced size, fast response time, better contrast ratio against the existing designs and high bit rates of 1.88 Tbit/s and 1.55 Tbit/s for NOT and NOR gates respectively. The amplitude of the optical signal larger than 0.5 arbitrary units (a.u.) and less than 0.1 (a.u.) at output are considered as logic ‘1’ and ‘0’ respectively. The gates are implemented in third optical window at the wavelength of 1.55 µm. RSoft FullWAVE simulator is used to perform simulation.

Frequency doubling of femtosecond laser pulses in three dimensional nonlinear photonic crystals

Quasi-phase matched nonlinear frequency conversion in three dimensional nonlinear photonic crystals (NPCs) has been considered for implementation of the second harmonic generation of transform-limited and chirped femtosecond laser pulses. Spatial distribution of the second harmonic intensity is shown to be caused by Cherenkov- and Raman–Nath-type nonlinear diffraction. These types of nonlinear diffraction may occur simultaneously resulting in an efficient multi-order nonlinear diffraction in the Bragg regime, which can be realized by a proper choice of the modulation period of NPC structure in longitudinal direction for considered transverse diffraction order. Three dimensional NPCs open up new possibilities for ultrafast nonlinear photonics and parametric interactions in optics.

Coupling of topological interface states in 1D photonic crystal

Coupling of topological interface states in a one dimensional photonic crystal has been systematically investigated in a broad energy region of electromagnetic spectrum. The robust topological interface states appear when the Zak phase between the adjoining photonic crystals are different at their common photonic bandgap. The coupled interface states created combining three photonic crystals are useful for the spatial confinement and enhancement of electric fields, which could find potential applications in nonlinear photonics and multichannel filters. Anticrossing observed in the dispersion confirms the strong coupling between the topological interface states and causes Rabi-like splitting between them. The splitting energy is found decreasing with increasing number of unit cells in the photonic crystal. The angular and polarization dependency of the coupled states are studied in detail. The resonant wavelength position and bandwidth of the dual reflectivity dips corresponding to the coupled interface states are polarization sensitive and tunable with varying angle of incidence of light.

New designs of 4 × 2 photonic crystal encoders using ring resonators

Optical encoders are pivotal elements in optical communication applications. There is much need for ultra-compact and high-speed novel designs. This work proposes two new designs of fast, compact 4 × 2 optical encoders using two dimensional photonic crystals. The proposed structures consist of square lattice silicon rods embedded in an air background. The operation of these encoders is based on the wave interference technique. The encoders are designed to help in achieving better performance through increasing the contrast ratio and decreasing the power loss and the return loss. The PWE method is used to analyze the photonic band gap. We used FDTD simulation to obtain the electric field distribution inside each structure and the normalized output power. We prove that the scattering rods improve the directivity of the light toward the desired paths and decrease the backward reflection. The proposed encoders have small footprint areas of 204.8 and 160.4 μm2 and operate at wavelength 1550 nm. They achieve low response time (254 and 163 fs) and high contrast ratio (6.69 and 12.9 dB). Simplicity and compactness of the designs make them suitable for optical signal processors and photonic integrated circuits. Another advantage of these designs is that low input power is enough for the encoders’ operation, because there is no non-linear materials included. Our designs compete with the published works in the last few years especially in their footprint and response time.

Numerical study of temperature and pressure effect on one dimensional random photonic crystal used as biosensors in the detection of breast cancer cells

For the past few decades, investigations of cancer cells were made using periodic/defective-periodic photonic structures. Utilizing the unique properties of a disordered photonic crystal for detecting the bio-analytes is still missing. This work incorporates the opto-biological properties of one-dimensional random photonic systems to design the two differently randomized biosensors for sensing breast cancer cells. These random sensors are differentiated from one another based on their random arrangements and random thicknesses. To obtain efficient outcomes, the thickness of the dielectric layers and sensing layer is optimized. Through the transfer matrix method, the sensing characteristics of the biosensors are investigated for different pressures (0–6 GPa) and temperatures (−125 °C to 25 °C). At the optimal range, the proposed Biosensors I and II, show a high sensitivity of 1372.549 nm/RIU. Among both sensors, Random Biosensor I exhibits a high-quality factor of 12925, a maximum FOM of 4575.163 RIU−1, and a very low detection limit in the order of 5.82857E-06 RIU. The designed sensor is capable of sensing very minuscule changes in the bio-analytes effectually. The proposed biosensor shows high sensitivity than the previous literature even in the normal incident of light.

Manipulation of electromagnetic waves induced by pseudomagnetic fields in two dimensional photonic crystals

Many interesting phenomena, such as quantization of Landau levels and quantum Hall effect, can occur in an electronic system under a strong magnetic field. However, photons do not carry charge, and they do not have many properties induced by external magnetic fields, either. Recently, the pseudomagnetic field, an artificial synthetic gauge field, has attracted intense research interest in classical wave systems, in which the propagation of the wave can be manipulated like in a real magnetic field. The photonic crystal is an optical structure composed of periodic material distributions and provides a good platform for studying the control of electromagnetic waves. In this work, we construct a uniform pseudomagnetic field by introducing uniaxial linear gradient deformation of metallic rods in a two-dimensional photonic crystal. The strong pseudomagnetic field leads to the quantization of photonic Landau levels in photonic crystal. The sublattice polarization of <i>n</i> = 0 Landau level is also demonstrated in our simulations. Unlike the real magnetic field, the pseudomagnetic fields of photonic crystal is opposite in two inequivalent energy valleys, and the time-reversal symmetry of the system is not broken. Our designed gradient photonic crystals support the transport of edge state in the gap between <i>n</i> = 0 and <i>n</i> = ±1 Landau levels. The edge state can propagate unidirectionally when it is excited by a chiral source. When a gaussian beam impinges on the photonic crystal, the propagating paths of two splitting beams can be controlled, which gives rise to the bend of two beams. Two photonic crystals with opposite pseudomagnetic fields are assembled together, and the interesting phenomenon of “snake-state” can be obtained. Our proposal opens the way for designing information processing devices by manipulating electromagnetic waves.