Design of diamond-shape photonic crystal fiber polarization filter based on surface plasma resonance effect

A novel plasmonic polarization filter based on the diamond-shape photonic crystal fiber(PCF) is proposed. The resonant coupling characteristics of the PCF polarization filter are investigated by the full-vector finite-element method. By optimizing the geometric parameters of the PCF, when the fiber length is 5 mm, the polarization filter has a bandwidth of 990 nm and an extinction ratio(ER) of lower than -20 dB. Moreover, a single wavelength polarization filter can also be achieved, along with an ER of -279.78 dB at wavelength 1.55 μm. It is believed that the proposed PCF polarization filter will be very useful in laser and optical communication systems.     

Highly sensitive photonic crystal fiber biosensor based on titanium nitride

A highly sensitive surface plasmon resonance photonic crystal fiber (PCF) biosensor based on Titanium Nitride (TiN) as a new alternative plasmonic material is proposed and analyzed. The TiN has high stability, high conductivity, and corrosion resistance which make it an ideal material for nanofabrication. The suggested biosensor is analyzed by full vectorial finite element method with perfectly matched layer as boundary conditions. In this paper, the biosensor geometrical parameters are studied to achieve high sensitivity for both polarized modes. A refractive index sensitivity of 7700 and 3600 nm/RIU for quasi-transverse electric and quasi transverse magnetic modes, respectively, are obtained. Additionally, the reported biosensor could be used for detecting an unknown analyte refractive index ranging from 1.32 to 1.34 with a high linearity. Further, the proposed biosensor structure is easy for fabrication using standard PCF fabrication current technologies.     

A novel design for single-polarization single-mode photonic crystal fiber at 1550 nm

The present paper proposes a novel design for achieving single-polarization single-mode (SPSM) operation at 1550 nm in photonic crystal fiber (PCF), using a rectangular-lattice PCF with two lines of three central air holes enlarged. The proposed PCF composed entirely of silica material is modeled by a full-vector finite element method with anisotropic perfectly matched layers. Simulations show that single-polarization operation within broad wavelength range can be easily realized with the proposed structure. The wideband SPSM operation features, the low confinement losses, and the small effective mode area are the main advantages of the proposed PCF structure. A SPSM-PCF with confinement loss less than 0.1 dB/km within wavelength range from 1370 to 1610 nm and effective mode area about 4.7 μm2 at 1550 nm is numerically demonstrated.     

光子晶体光纤气体传感灵敏度的有限差分法分析

提出了一种适合于高灵敏度气体传感器的新型光子晶体光纤结构.采用全矢量频域有限差分方法,研究了基于不同结构光子晶体光纤的气体传感器的相对灵敏度.由全矢量频域有限差分法,通过直接求解由麦克斯韦方程组导出的标准特征值方程,可以得到光纤中可能存在的不同模式的传播常量、电场分布和磁场分布.分别给出了三种不同结构光子晶体光纤在波长为1.3312 μm处,与结构参量变化对应的相对灵敏度变化以及在不同波长情况下的相对灵敏度变化.结果证明,该新结构具有较其它代表性的折射率引导型光子晶体光纤结构更高的灵敏度,特别适合作气体传感器.     

太赫兹正六边形光子晶体光纤的液体传感

设计了一种分别填充水、酒精和苯炔等边三角形空气孔纤芯、包层空气孔排列为正六边形结构、以环烯烃共聚物作为基底材料的光子晶体光纤,利用有限元法模拟了0.3~1.5 THz频带内的液体传感特性。结果表明,设计的光子晶体光纤的灵敏度系数很高,当纤芯空气孔直径d₁=2.4 μm、包层空气填充比为0.3时,苯炔在频率0.3 THz的相对灵敏性系数最高为37.63%,在1.5 THz,限制损耗的数量级可以降至10^-7。     

一种新型高双折射光子晶体光纤

提出了一种新的高双折射光子晶体光纤结构.应用全矢量频域有限差分方法所做的数值分析表明：该结构光纤基模的两个正交偏振态不再简并，其模式呈现很强的线偏振特性,并且模式双折射与结构参数设置有密切关系.通过选择合适的结构参数，可以使之达到10^-2量级，比传统的D型和熊猫型保偏光纤高出2个数量级.合理设计光纤包层的几何结构，可以取得理想的色散效果.这种结构的光子晶体光纤可用于制作具有适当色散特性或偏振特性的保偏光纤及相关光纤器件. 关键词： 光子晶体光纤 模式双折射 偏振特性 频域有限差分法     

Broadly tunable one-way terahertz plasmonic waveguide based on nonreciprocal surface magneto plasmons

One-way-propagating broadly tunable terahertz plasmonic waveguide at a subwavelength scale is proposed based on a metal-dielectric-semiconductor structure. Unlike other one-way plasmonic devices that are based on interference effects of surface plasmons, the proposed one-way device is based on nonreciprocal surface magneto plasmons under an external magnetic field. Theoretical and simulation results demonstrate that the one-way-propagating frequency band can be broadly tuned by the external magnetic fields. The proposed concept can be used to realize various high performance tunable plasmonic devices such as isolators, switches and splitters for ultracompact integrated plasmonic circuits.     

Characteristics analysis of extruded elliptical hole photonic crystal fibers with square air-core

An extruded elliptical hole photonic crystal fibers PCF with square air-core is proposed. By using a full vector finite-element method FV-FEM and anisotropic perfectly matched layers APML, the structure and optical properties of the proposed PCF are analyzed. Simulation results show that the birefringence of the proposed photonic crystal fiber can be up to the order of 10⁻², and has a flattened dispersion from 1.20 μm to 1.80 μm. The proposed PCF may have important application in super-continuum SC generation, dispersion compensation, fiber-optic sensing systems and other aspects.     

Enhancement of Optical Second Harmonic Generation in Hybrid Plasmonic–Photonic Microcavities

A one-dimensional combined plasmonic–photonic system tailored for the enhancement of nonlinear optical effects is proposed and implemented. In this structure, a layer of silver plasmonic nanoparticles is placed in the cavity region of a photonic-crystal microcavity made of porous silicon. A multifold increase in an optical second harmonic generation signal in comparison to the structure without plasmonic nanoparticles is demonstrated.     

深亚波长约束的表面等离子体纳米激光器研究

本文提出了一种新颖的基于半导体纳米线/空气间隙/金属薄膜 复合结构的表面等离子体纳米激光器, 并给出了理论研究和仿真分析. 这种结构通过金属界面的表面等离子体模式与高增益介质纳米线波导模式耦合, 从而使场增强效应得到显著提高. 同时通过数值仿真研究, 得到该混合波导结构的模式特性和增益阈值随空气槽宽度、纳米线半径的变化规律, 表明它可以实现对输出光场的深亚波长约束, 同时保持低损耗传输和高场强限制能力. 通过最优化选择, 最终得到纳米等离子体激光器的最优结构尺寸. 关键词： 表面等离子体 混合等离子体波导 纳米激光器     

Design of highly birefringent chalcogenide glass PCF: A simplest design

In this article, a new simplified structure of a highly birefringent chalcogenide As₂Se₃ glass photonic crystal fiber (PCF) is designed and analyzed by using fully vectorial finite element method. The effective indices, confinement loss, birefringence, and chromatic dispersion of fundamental polarized mode are calculated in the proposed PCF for a wide wavelength range. To maintain the polarization in chalcogenide As₂Se₃ glass PCF, we enlarged two of the central air holes and reduced two transverse air holes for achieving high birefringence. This helps in creating an effective index difference between the two orthogonal polarization modes. It is also shown that As₂Se₃ glass PCF provides lower chromatic dispersion and less confinement loss compared to silica PCF of the same structure in wavelength range 1.3 to 1.8 μm and hence such chalcogenide As₂Se₃ glass PCF have high potential to be used in dispersion compensating and birefringence application in optical communication systems. In addition to this, the polarization mode dispersion (PMD) result of the proposed PCF is also reported.     

Design of a surface plasmon resonance biosensor based on photonic crystal fiber with elliptical holes

In this paper, a photonic-crystal fiber based plasmonic biosensor in which gold is used as the plasmonic material is proposed. The introduced sensor is designed in such a way that the plasmonic metal layer and the sensing layer are placed outside the fiber structure so that the fabrication process and the numerical analysis has become comparatively much easier. The proposed plasmonic biosensor properties are calculated numerically using the finite element method. Amongst the parameters affecting the performance of the biosensor are the thickness of the gold layer and the diameter of the central cavity. By applying the wavelength interrogation method, the maximum sensitivity and the resolution of the proposed biosensor are computed as 5723.5 nm/RIU and 1.74?×?10^?5 RIU, respectively. The proposed structure with the above properties is suitable for detecting biological molecules, organic chemicals and analytes.     

Analysis of high birefringence photonic crystal fiber with octagonal and squarely lattice

Aiming at the requirement of high birefringence, a new kind of photonic crystal fiber (PCF) with octagonal and squarely lattice is proposed. In this structure, squarely lattices are added in the inner layer to obtain high birefringence. Birefringence and dispersion as a function of wavelength and size of PCF are analyzed by using Finite Element Method (FEM). Simulation results show that this kind of PCF exhibits high birefringence with a magnitude of 10^?3, and one zero dispersion point is obtained simultaneously. In addition, the characteristics of PCF can be tuned by changing the size of fiber.     

A polymer photonic crystal fiber with high and flattened birefringence

A novel high birefringence polymer photonic crystal fiber (PCF) is proposed in this work. This PCF is composed of a polymer core and a cladding with elliptical air holes and squeezed triangular lattice. The high birefringence is introduced on the combined effect of elliptical air holes and the squeezed lattice. Our numerical results based on the supercell lattice method indicate that the birefringence can reach as high as 0.0018 at 650 nm wavelength with a properly designed cladding structure. We also analyze the dependence of the birefringence on structure parameters. And we design a PCF that has high and flattened birefringence.     

用于液体传感的高双折射新型光子晶体光纤结构

提出一种用于液体传感的光子晶体光纤的结构和设计方法。将六边形光子晶体光纤的纤芯区域设计成2个椭圆空气孔,分别填充水和乙醇,进而比较两种光子晶体光纤结构的传播特性。采用全矢量有限元法对所设计光子晶体光纤结构的双折射、相对灵敏度、限制损耗、非线性系数进行数值分析,对光纤各项参数的优化及纤芯椭圆结构参数进行调整,结果表明:当椭圆率为0.6时,纤芯填充乙醇的光子晶体光纤PCF2在波长1.55 nm处相对敏感度可达到72.506 7%,同时限制损耗可以降至10?8级。所设计的模型可用于传感和生物传感研究及应用。     

Ultra-compact two-dimensional plasmonic nano-ring antenna array for sensing applications

In this paper, a novel optical nanoantenna based on two-dimensional plasmonic nano-ring antenna array is proposed, investigated numerically and compared with a nano-disk antenna array. The results show that the nano-ring structure has resonances similar to the resonances of nano-disk structure but in higher wavelengths. These resonances are tunable by varying the structural parameters of the ring. The optical properties of the proposed structure are investigated in the context of designing a plasmonic refractive index sensor. The nano-ring antenna array sensor has large sensitivity in comparison to the conventional nano-disk antenna arrays. The special feature of the presented structure and the device concepts introduced in this work are applicable in realization of various integrated components and could play an important role in development of plasmonic sensors.     

Insulator—insulator—metal plasmonic waveguide for parasitic scattering suppression in plasmonic optics

We have shown using rigorous electromagnetic simulations that a planar structure consisting of two isotropic dielectric layers can be used to reduce parasitic scattering in plasmonic elements by an order-of-magnitude (to 1–3%). The proposed approach can be used for designing various plasmonic elements such as lenses, Bragg reflectors and plasmonic crystals.     

Gain-assisted optical switching in plasmonic nanocavities

A plasmonic cavity filled with active material is proposed to explain optical switching. Optical properties, including transmission, response time, and field distribution of on/off state, are numerically investigated. We demonstrate that such a gain-assisted plasmonic structure can achieve optical switching in the nan- odomain and shorten the switching time to the subpicosecond level. Our results indicate the potential application of the proposed structure in optical communication and photonic integrated circuits.     

Novel large negative dispersion and tunable zero dispersion wavelength of photonic crystal fiber

The article describes a novel doped CS₂ core photonic crystal fiber with high negative chromatic dispersion. The proposed design is simulated through a full-vector finite element method and anisotropic perfectly matched layers. The numerical results show that we can achieve a negative dispersion coefficient of ?5600 ps/(nm km) almost at the wavelength of 1.55 μm by carefully adjusting the proposed PCF structure parameters. The proposed PCF may have great potential applications in dispersion compensating, optical parametric amplification, and optical fiber communication.     

Novel single-mode and polarization maintaining photonic crystal fiber

In this paper, we present and propose a novel structure for improved birefringence and single-mode propagation condition photonic crystal fiber (PCF) in a broad range of wavelength. The birefringence of the fundamental mode and single mode property in such a PCF is numerically estimated by employing full vector finite element method (FVFEM) and anisotropic perfectly matched layers (APML). The simulation results illustrate that we can achieve a high birefringence and perfect single-mode condition by employing silica-filled into one-line elliptical air holes parallel to x-axis and rotated by an angle. Obviously, the proposed PCF is quite useful for optical devices.