- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Design and analysis of multi-hexagonal reversible encoder using photonic crystals
摘要： In this paper, a 4 × 2 reversible encoder with hexagonal lattice has been designed using two-dimensional photonic crystals with non-linear refractive index. In order to demonstrate the working of the encoder, we have used the multi-hexagonal shaped structure arranged in parallel with appropriate inclination to get the desired output. During its functionality as an encoder, more than 98% of the power is coupled at the output port to obtain logic 1 and less than 17.2% of the power is coupled for obtaining logic 0. In addition, during its functionality as a reversible encoder, the logic 1 and logic 0 correspond to 97.5% and 15.1%, respectively. The proposed encoder provides an improved contrast ratio of 12.18? dB and 11.5?dB for logical states of 01 and 10, respectively.
关键词： Photonic integrated circuits,Optical reversible encoder,Photonic crystal,Photonic band gap
更新于2025-09-23 15:21:21
-
Approximate photonic bandgaps of dielectric-magnetic one-dimensional photonic crystals
摘要： The one dimensional photonic crystals (1DPCs) that have both the permittivity and permeability varying periodically along the same direction are analyzed theoretically using the coupled-mode theory. The approximate band edge frequencies, center frequencies, and the bandgaps are derived for the axial propagation. The results are elegant generalization of the corresponding results of the dielectric 1DPCs. The approximate bandedge frequencies obtained were found to have good agreement with those obtained by the transfer matrix method.
关键词： One-dimensional photonic crystal,Coupled-mode theory,Dielectric-magnetic photonic crystal
更新于2025-09-23 15:21:21
-
Integrable all-optical pass switch
摘要： A completely new design for an all-silicon all-optical pass switch has been proposed based on the stimulated Raman scattering (SRS) in silicon nanocrystal embedded slotted photonic crystal waveguide (SPCW). Substantial miniaturisation in the device footprint and operating power has been attained by merging the benefits of the giant SRS gain and the ultra-high optical confinement of the SPCW. The proposed switch offers a tremendously high contrast ratio of (cid:1) 27 dB between the logic levels and an extraordinary bit rate of 125 Gbps.
关键词： high bit rate,stimulated Raman scattering,high contrast ratio,slotted photonic crystal waveguide,silicon nanocrystal,all-optical pass switch
更新于2025-09-23 15:21:21
-
Rectangular Lattice Photonic Crystal Fiber with Simultaneous Polarization Filtering at Communication Wavelengths of 1310 nm and 1550 nm
摘要： In this study, we developed a tunable photonic crystal fiber (PCF) polarized filter with a gold coating and liquid filling, which was investigated using the full-vector finite-element method. The gold that selectively filled the cladding air holes acted as a defect mode. When light was transmitted into the core, the energy was transferred from the core mode to the defect mode at a given wavelength and a resonance peak was obtained. Numerical results showed that the proposed PCF could be implemented simultaneously for polarization filtering in the communication windows of 1.31 and 1.55 μm. The confinement losses for the y-polarized mode were 251.5 dB/cm for 1.31 μm and 375.3 dB/cm for 1.55μm. When the fiber length was 90 μm, the corresponding bandwidths were just less than 20 and 70 nm for 1.31 and 1.55 μm, respectively. The bandwidths are the narrowest obtained and they are conducive to applications in integrated systems. We also studied the effects of structural parameters on the resonance performance. The optical fiber structure could be optimized further to obtain better results.
关键词： Photonic crystal fiber,Polarization filter,Full-vector finite element method
更新于2025-09-23 15:21:21
-
Optical Fiber Sensors Based on Microstructured Optical Fibers to Detect Gases and Volatile Organic Compoundsa??A Review
摘要： Since the first publications related to microstructured optical fibers (MOFs), the development of optical fiber sensors (OFS) based on them has attracted the interest of many research groups because of the market niches that can take advantage of their specific features. Due to their unique structure based on a certain distribution of air holes, MOFs are especially useful for sensing applications: on one hand, the increased coupling of guided modes into the cladding or the holes enhances significantly the interaction with sensing films deposited there; on the other hand, MOF air holes enhance the direct interaction between the light and the analytes that get into in these cavities. Consequently, the sensitivity when detecting liquids, gasses or volatile organic compounds (VOCs) is significantly improved. This paper is focused on the reported sensors that have been developed with MOFs which are applied to detection of gases and VOCs, highlighting the advantages that this type of fiber offers.
关键词： humidity and volatile organic compounds,solid core photonic crystal fibers,microstructured optical fibers,gasses,hollow core photonic crystal fibers,suspended core microstructured optical fibers
更新于2025-09-23 15:21:01
-
Non-Lorentzian Local Density of States in Coupled Photonic Crystal Cavities Probed by Near- and Far-Field Emission
摘要： Recent theories proposed a deep revision of the well-known expression for the Purcell factor, with counterintuitive effects, such as complex modal volumes and non-Lorentzian local density of states. We experimentally demonstrate these predictions in tailored coupled cavities on photonic crystal slabs with relatively low optical losses. Near-field hyperspectral imaging of quantum dot photoluminescence is proved to be a direct tool for measuring the line shape of the local density of states. The experimental results clearly evidence non-Lorentzian character, in perfect agreement with numerical and theoretical predictions. Spatial maps with deep subwavelength resolution of the real and imaginary parts of the complex mode volumes are presented. The generality of these results is confirmed by an additional set of far-field and time-resolved experiments in cavities with larger modal volume and higher quality factors.
关键词： non-Lorentzian local density of states,Purcell factor,quantum dot photoluminescence,photonic crystal cavities,near-field hyperspectral imaging
更新于2025-09-23 15:21:01
-
Semiconducting Metal Oxide Photonic Crystal Plasmonic Photocatalysts
摘要： Plasmonic photocatalysis has facilitated rapid progress in enhancing photocatalytic efficiency under visible light irradiation. Poor visible-light-responsive photocatalytic materials and low photocatalytic efficiency remain major challenges. Plasmonic metal–semiconductor heterostructures where both the metal and semiconductor are photosensitive are promising for light harvesting catalysis, as both components can absorb solar light. Efficiency of photon capture can be further improved by structuring the catalyst as a photonic crystal. Here, the synthesis of photonic crystal plasmonic photocatalyst materials using Au nanoparticle-functionalized inverse opal (IO) photonic crystals is reported. A catalyst prepared using a visible-light-responsive semiconductor (V2O5) displayed over an order of magnitude increase in reaction rate under green light excitation (λ = 532 nm) compared to no illumination. The superior performance of Au-V2O5 IO is attributed to spectral overlap of the electronic bandgap, localized surface plasmon resonance, and incident light source. For the Au-TiO2 catalyst, despite coupling of the LSPR and excitation source at λ = 532 nm, this is not as effective in enhancing photocatalytic activity compared to carrying out the reaction under broadband visible light, which is attributed to improved photon adsorption in the visible by the presence of a photonic bandgap, and exploiting slow light in the photonic crystal to enhance photon absorption to create this synergistic type of photocatalyst.
关键词： photonic crystal,nitrophenol reduction,catalyst,plasmonic nanoparticles,photocatalysis
更新于2025-09-23 15:21:01
-
Effective Parameters for 1D Photonic Crystals with Isotropic and Anisotropic Magnetic Inclusions: Coherent Wave Homogenization Theory
摘要： A homogenization theory that can go beyond the regime of long wavelengths is proposed, namely, a theory that is still valid for vectors of waves near the edge of the first zone of Brillouin. In this paper, we consider that the displacement vector and the magnetic induction fields have averages in the volume of the cell associated with the values of the electric and magnetic fields in the edges of the cell, so they satisfy Maxwell’s equations. Applying Fourier formalism, explicit expressions were obtained for the case of a photonic crystal with arbitrary periodicity. In the case of one-dimensional (1D) photonic crystals, the expressions for the tensor of the effective bianisotropic response (effective permittivity, permeability and crossed magneto-electric tensors) are remarkably simplified. Specifically, the effective permittivity and permeability tensors are calculated for the case of 1D photonic crystals with isotropic and anisotropic magnetic inclusions. Through a numerical calculation, the dependence of these effective tensors upon the filling fraction of the magnetic inclusion is shown and analyzed. Our results show good correspondence with the approach solution of Rytov’s effective medium. The derived formulas can be very useful for the design of anisotropic systems with specific optical properties that exhibit metamaterial behavior.
关键词： metamaterial,homogenization theory,effective parameters,photonic crystal
更新于2025-09-23 15:21:01
-
[IEEE 2019 4th International Conference on Electrical Information and Communication Technology (EICT) - Khulna, Bangladesh (2019.12.20-2019.12.22)] 2019 4th International Conference on Electrical Information and Communication Technology (EICT) - Poisonous Chemical Sensing Using Highly Sensitive Terahertz Photonic Crystal Fiber Sensor
摘要： We propose two hollow core photonic crystal fiber (PCF) based sensors for the detection of toxic chemical like hydrogen cyanide (HCN) in the terahertz range. Because of its high level of toxicity and the potential threat it poses to humans, it is imperative to have a malleable and proficient method for HCN detection. Among the two proposed PCF sensors, the sensor which has octagonal shaped hollow core with a circular shaped air hole in the cladding provides a high relative sensitivity of 92.08% and a low confinement loss at 1.4 THz frequency.
关键词： Photonic crystal fiber,Hydrogen Cyanide,Sensitivity,Effective area,Confinement loss
更新于2025-09-23 15:21:01
-
Quantum Hall phase and chiral edge states simulated by a coupled dipole method
摘要： We present theoretical modeling of the quantum Hall phase and chiral edge states in a gyroelectric photonic crystal. The theoretical framework represented here is based on a coupled dipole method, which is a direct counterpart of the tight-binding approximation. We con?rm that gyrotropic coupling produces a band gap characterized by a nonzero Chern number. Gapless edge states appear at an interface between a gyroeletric photonic crystal and a vacuum. At a domain wall between media of positive and negative gyrotropy, topological edge states that are analogous to the Jackiw-Rebbi states are observed. Propagation of the chiral edge states is also simulated in real space under excitation of an external dipole source. This analysis provides a toy model to describe the quantum Hall phase in a purely optical manner, without using a mapping or an analogy of the electron wave function in the quantum Hall effect.
关键词： quantum Hall phase,chiral edge states,coupled dipole method,topological edge states,gyroelectric photonic crystal
更新于2025-09-23 15:21:01