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A Large Detection-Range Plasmonic Sensor Based on An H-Shaped Photonic Crystal Fiber
摘要： An H‐shaped photonic crystal fiber (PCF)‐based surface plasmon resonance (SPR) sensor is proposed for detecting large refractive index (RI) range which can either be higher or lower than the RI of the fiber material used. The grooves of the H‐shaped PCF as the sensing channels are coated with gold film and then brought into direct contact with the analyte, which not only reduces the complexity of the fabrication but also provides reusable capacity compared with other designs. The sensing performance of the proposed sensor is investigated by using the finite element method. Numerical results show that the sensor can work normally in the large analyte RI (na) range from 1.33 to 1.49, and reach the maximum sensitivity of 25,900 nm/RIU (RI units) at the na range 1.47–1.48. Moreover, the sensor shows good stability in the tolerances of ±10% of the gold‐film thickness.
关键词： fiber optics sensors,photonic crystal fiber,refractive index sensor,surface plasmon resonance
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - Sozopol, Bulgaria (2019.9.6-2019.9.8)] 2019 IEEE 8th International Conference on Advanced Optoelectronics and Lasers (CAOL) - The Autoconvolution Method Use for Positioning Photonic Crystal Fibers
摘要： In this paper, the autoconvolution method was investigated to determine the position of the longitudinal axis of the photonic crystal fiber and to determine the center of the mode field in the cross section. Knowing the center of the PCF mode field, one can determine the cross section in which the diameter of the mode field will be maximal. This allows a more precise positioning of two identical PCF during connection. The proposed method allows improving the quality of the positioning of the PCF by transverse, angular, longitudinal displacements, and also by the mutual angle of rotation of the connected PCFs.
关键词： optical fibers control,optical power loss,photonic crystal fiber,optical fiber connection,autoconvolution method,mode field,near-field technique
更新于2025-09-23 15:19:57
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High-Brightness Low-Divergence Tapered Lasers with a Narrow Taper Angle
摘要： High-brightness tapered lasers with photonic crystal structures are designed and fabricated. A narrow taper angle is designed for the tapered section. The device delivers an output power of 3.3 W and a maximum wall-plug efficiency of 43%. The vertical beam divergence is around 11° at different currents. Nearly diffraction-limited beam qualities for the vertical and lateral directions are obtained. The lateral beam quality factor ?? 2 is below 2.5 and the vertical ?? 2 value is around 1.5 across the whole operating current range. The maximum brightness is 85 MW·cm?2sr?1. When the current is above 3.3 A, the brightness is still above 80 MW·cm?2sr?1.
关键词： photonic crystal structures,tapered lasers,High-brightness,brightness,beam quality
更新于2025-09-23 15:19:57
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Enhanced Goos-H?¤nchen shift of graphene coated on one-dimensional photonic crystal
摘要： The enhancement of Goos-H?nchen shift of graphene coated on a truncated one-dimensional photonic crystal is proposed and theoretically investigated. The proposed band-gap con?guration featuring highly electric ?eld enhancement and con?nement on the graphene surface enables the excitation of Bloch surface wave mode. By taking full advantages of the remarkable optical properties of the excited optical surface wave mode, a large phase variation appears near the band-gap of the proposed structure, leading to a dramatically enhanced Goos-H?nchen shift. Leveraging this giant Goos-H?nchen shift, the sensing capability of this proposed structure is discussed, implicating a superior performance in Goos-H?nchen shift sensing applications.
关键词： Graphene,Optical instruments,Optics at surfaces,One-dimensional photonic crystal
更新于2025-09-23 15:19:57
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An air-core photonic crystal fiber based plasmonic sensor for high refractive index sensing
摘要： Most surface plasmon resonance (SPR) based photonic crystal fiber (PCF) sensors have been designed to detect the analyte refractive index (RI) ranging from 1.33?1.41. In this paper, we propose a new approach to extend the detection range of the sensor, and it can be fabricated with the existing fabrication techniques. Contrary to the existing PCF based sensors, our designed sensor is based on an air-core PCF where analyte is placed to the core of the PCF through a vertical side opening channel and is able to detect RI of the analyte higher than that of the PCF background. We use a chemically stable plasmonic material (i.e., gold), where the plasmonic material and analyte are placed in such a way that there is no direct contact between them, thus reducing the interference effect. According to our simulation, we show that the spectral sensitivity and resolution are achieved as 11,700 nm/RIU and 8.55×10–6 RIU, respectively, for the analyte RI of 1.42. We believe that our proposed sensor can be used to detect highly active chemical and biological liquid samples.
关键词： optical fiber sensors,Photonic crystal fiber,surface plasmon resonance
更新于2025-09-23 15:19:57
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Signal amplified photoelectrochemical assay based on Polypyrrole/g-C3N4/WO3 inverse opal photonic crystals triple heterojunction assembled through sandwich-type recognition model
摘要： A novel photoelectrochemical (PEC) sensing strategy with an amplified signal was proposed based on polypyrrole/g-C3N4/WO3 inverse opal photonic crystals triple heterojunction. The sandwich-type detection model was applied to increase the sensitivity and favor the assembly of heterojunction structure. The heterojunction among PPy, g-C3N4 and WO3 highly improved the separation of photo-generated charges. Meanwhile, WO3 IOPCs with good optical performance were employed to enhance the light absorption of PEC detection electrode. With the simultaneous combination of these amplification techniques, the designed PEC sensor achieved high sensitivity with low limit of detection (LOD) as 0.004 nM (≈ 1.99 ng L?1) and admirable selectivity in the detection of oxytetracycline under visible light irradiation.
关键词： Sandwich-type,Signal amplification,Inverse opal photonic crystal,Photoelectrochemical,Heterojunction
更新于2025-09-23 15:19:57
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Double-mode absorption in double-defect photonic crystal with one graphene multilayer
摘要： In order to realize the double-mode absorption, double-defect photonic crystal is formed. For the upper defect, the graphene multilayer is placed on the top of photonic crystal acting as the surface defect, while for the one below, the pure dielectric destroying the periodicity of photonic crystal services as the internal defect. Depending on FP resonance, two modes achieve perfect absorption at critical coupling. Merely, the mode-dependences are different, so that these modes have different distinctly Q factors and can be tuned independently by changing the chemical potential of graphene and the size of defect. Combining the angle response, the independence-tuning of modes becomes more flexible. Besides, both of modes’ frequencies and amplitudes are enslaved to the layer number of graphene. And the period of photonic crystal affects directly the peak–peak distance and modes number.
关键词： Double-mode absorption,Double-defect photonic crystal,FP resonance,Critical coupling,Graphene multilayer
更新于2025-09-23 15:19:57
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Methanol-Filled Hybrid Photonic Crystal Fiber with High Birefringent and Negative Dispersion
摘要： A unique hexagonal lattice structure of silica-based solid core photonic crystal fiber (PCF) surrounded by array of air holes is proposed. The cladding portion of the structure consists of five rings where core is made up of 11 small rings filled with methanol. Three different-shaped structures are used to analyze the effect on PCF parameters where the first structure uses circular air holes in cladding and core, the second structure consists of circular air holes in cladding and elliptical air holes in core, and the last structure was designed by using elliptical air holes in both cladding and core. Optical properties birefringence, confinement loss, and negative dispersion have been found theoretically and compared. A novel and relatively simple approach depicts the results that attain high birefringence, low confinement loss, and negative dispersion. It is found that the presence of elliptic air holes instead of circular air holes in the core region and the cladding brings higher birefringence, low confinement loss, and highly negative dispersion.
关键词： Photonic crystal fiber,Effective refractive index,Dispersion,Birefringence,Confinement loss
更新于2025-09-23 15:19:57
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Nonlinear dynamic analysis of a photonic crystal nanocavity resonator
摘要： A nonlinear dynamic model of a one-dimensional photonic crystal nanocavity resonator is presented. It considers the internal tensile stress and the geometric characteristics of a photonic crystal with rectangular (and circular) holes. The solution of the dynamic model shows that the internal tensile stress can suppress the hardening and softening behaviors of the resonator. However, the stress can reduce the amplitude, which is not conducive to an improvement of the sensitivity of the sensor. It is demonstrated that with an optimized beam length, the normalized frequency drift of the beam can be stabilized within 1% when the optical power increases from 2 mW to 6 mW. When the hole size of the resonator beam is close to the beam width, its increase can lead to a sharp rise of the resonant frequency and the promotion of hardening behavior. Moreover, the increase in the optical power initially leads to the softening behavior of the resonator followed by an intensi?cation of the hardening behavior. These theoretical and numerical results are helpful in understanding the intrinsic mechanism of the nonlinear response of an optomechanical resonator, with the objective of avoiding the nonlinear phenomena by optimizing key parameters.
关键词： photonic crystal,softening and hardening behaviors,nonlinear dynamic,resonator
更新于2025-09-23 15:19:57
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Four-channel THz wave routing switch based on magneto photonic crystals
摘要： A four-channel routing switch based on a square lattice 2-D silicon photonic crystal with four point defects and five line defects is proposed. In this scheme, the properties that magnetic permeability of the ferrite material changing with external magnetic field and the coupling characteristics between line defect and point defect are used. The proposed device is theoretically analyzed and numerically investigated by using plane wave method (PWM) and finite-difference time-domain (FDTD). The results show that the four-channel routing switch can be realized by applying different intensity of magnetic fields. The extinction ratios of the four channels are all more than 13dB, the transmittance rates are higher than 93%, the insertion losses are lower than 0.288dB, and steady times are less than 50 ps. The proposed THz routing switch has potential applications in terahertz wave integrated circuit fields in the future.
关键词： THz wave；routing switch；magneto photonic crystal
更新于2025-09-23 15:19:57