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Investigation of a Bragg Grating-Based Fabrya??Perot Structure Inscribed Using Femtosecond Laser Micromachining in an Adiabatic Fiber Taper
摘要： This paper presents the fabrication of a fiber Bragg grating (FBG)-based Fabry–Perot (FP) structure (7 mm total length) in an adiabatic fiber taper, investigates its strain and temperature characteristics, and compares the sensing characteristics with a standard polyimide coated FBG sensor. Firstly, a simulation of the said structure is presented, followed by the fabrication of an adiabatic fiber taper having the outer diameter reduced to 70 μm (core diameter to 4.7 μm). Next, the sensing structure, composed of two identical uniform FBG spaced apart by a small gap, is directly inscribed point-by-point using infrared femtosecond laser (fs-laser) micromachining. Lastly, the strain and temperature behavior for a range up to 3400 με and 225 ?C, respectively, are investigated for the fabricated sensor and the FBG, and compared. The fabricated sensor attains a higher strain sensitivity (2.32 pm/με) than the FBG (0.73 pm/με), while both the sensors experience similar sensitivity to temperature (8.85 pm/?C). The potential applications of such sensors include continuous health monitoring where precise strain detection is required.
关键词： Fabry–Perot,microfiber sensor structure,direct writing,sensor for structural health monitoring,point-by-point fabrication,femtosecond laser micromachining,harsh environment fiber sensor
更新于2025-09-23 15:19:57
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Self-Powered Humidity Sensor Using Chitosan-Based Plasmonic Metal-Hydrogel-Metal Filters
摘要： A tunable Fabry–Pérot resonator is realized using metal–insulator–metal structure, in which the insulator is chitosan hydrogel. The chitosan swells in response to changes in relative humidity; this change affects transmissive structural color of the multilayer structure. This tunable resonator is utilized for a humidity sensor combined with a photovoltaic cell. The change in current through the photovoltaic cell provides rapid precise measurement of relative humidity, and the change in color of the multilayer provides an approximate, remotely-readable estimate. The response requires no power, so the device has numerous sensing applications.
关键词： Fabry–Pérot etalon,structural colors,tunable color filter,tunable structural colors,interferometric colors,metal–insulator–metal
更新于2025-09-23 15:19:57
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A Novel Fabry-P??rot Optical Sensor for Guided Wave Signal Acquisition
摘要： In this paper, a novel hybrid damage detection system is proposed, which utilizes piezoelectric actuators for guided wave excitation and a new ?bre optic (FO) sensor based on Fabry-Perot (FP) and Fiber Bragg Grating (FBG). By replacing the FBG sensors with FBG-based FP sensors in the hybrid damage detection system, a higher strain resolution is achieved, which results in higher damage sensitivity and higher reliability in diagnosis. To develop the novel sensor, optimum parameters such as re?ectivity, a wavelength spectrum, and a sensor length were chosen carefully through an analytical model of the sensor, which has been validated with experiments. The sensitivity of the new FBG-based FP sensors was compared to FBG sensors to emphasize the superiority of the new sensors in measuring micro-strains. Lastly, the new FBG-based FP sensor was utilized for recording guided waves in a hybrid setup and compared to the conventional FBG hybrid sensor network to demonstrate their improved performance for a structural health monitoring (SHM) application.
关键词： ?ber optic sensors,guided waves,structural,health monitoring,hybrid PZT-FBG,Fabry-Perot
更新于2025-09-23 15:19:57
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Lithography-Free Planar Band-Pass Reflective Color Filter Using A Series Connection of Cavities
摘要： In this article, a lithography-free multilayer based color filter is realized using a proper series connection of two cavities that shows relatively high efficiency, high color purity, and a wide view angle. The proposed structure is a metal-insulator-metal-insulator-semiconductor (MIMIS) design. To optimize the device performance, at the first step, transfer matrix method (TMM) modeling is utilized to find the right choices of materials for each layer. Simulations are carried out later on to optimize the geometries of the layers to obtain our desired colors. Finally, the optimized devices are fabricated and experimentally characterized to evaluate our modelling findings. The characterization results of the fabricated samples prove the successful formation of efficient and wide view angle color filters. Unlike previously reported FP based designs that act as a band-stop filter in reflection mode (absorbing a narrow frequency range and reflecting the rest of the spectrum), this design generates a specific color by reflecting a narrow spectral range and absorbing the rest of the spectrum. The findings of this work can be extended to other multilayer structures where an efficient connection of cavities in a tandem scheme can propose functionalities that cannot be realized with conventional FP resonators.
关键词： lithography-free,Fabry-Perot,MIMIS,color filter,RGB colors,angular insensitivity,reflection mode
更新于2025-09-19 17:15:36
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Terahertz Metalens for Multifocusing Bidirectional Arrangement in Different Dimensions
摘要： Metasurface lenses are typically investigated for a lot of characteristics, but the design method for conventional devices is comparatively simple in terms of controlling the quantity, position, and size of focal spots. Herein, ultra-thin-phase metasurface structures based on complementary square-split-ring (SSR) nanoantennas have been proposed to achieve terahertz (THz) optical metalenses with multidimensionality and multifocusing. The principle of beam propagation and efficient transmission can be effectively explained through the Fabry–Pérot resonance mode. The THz metalens can efficiently transfer linear cross-polarization under the effects of gratings in the incident plane. By locally tailoring edge lengths and opening the angles of the split rings, full control over abrupt phase changes can be achieved. Two symmetrically distributed parallel focal spots and two vertical focal spots with arbitrary distance can be obtained by arranging the SSR units on the metalenses. Furthermore, we apply the concept of a partitioned-phase mode to realize a double-focusing metalens in the longitudinal direction, which provides a flexible and convenient method to achieve the desired focusing properties. The simulation results are expected to pave the way for practical use of metasurfaces in optical holography, optical-information coding, and parallel-particle trapping.
关键词： nanoantenna,phase shift,Multifocusing metalens,Fabry-Pérot-like resonance,terahertz
更新于2025-09-19 17:15:36
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Wideband circular polarized Fabry-Perot cavity antennas for V-band indoor point-to-point communications
摘要： In this paper, a 60 GHz planar Fabry-Perot cavity (FPC) antenna with a circularly polarized (CP) radiation characteristic is proposed as a good candidate for millimeter-wave wireless systems. A sparse array design is employed to enhance the gain bandwidth (GBW) product of the antenna. Complete formulations for circular polarized radiation are developed to serve as a general guideline scalable to any frequencies. The theoretical results using ideal point sources are validated by numerical analysis using the finite elements method (FEM). In the full-wave simulations, the ideal sources are replaced by four annular-ring slot antennas to excite the FPC.
关键词： Circular Polarized,V-Band Antennas,Fabry-Perot Cavity Antennas,Directive Antennas,Wideband Antennas
更新于2025-09-19 17:15:36
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[IEEE 2018 Asia Communications and Photonics Conference (ACP) - Hangzhou, China (2018.10.26-2018.10.29)] 2018 Asia Communications and Photonics Conference (ACP) - Design of Helical Tube Fiber Optic Fabry-Perot Cavity Pressure Sensor
摘要： An optical fiber helical tube pressure sensor based on Fabry-Perot cavity which is fabricated by CO2 laser thermal bonding technique is developed. The measuring range is 0~72MPa, the repeatability is 0.02% F·S and the hysteresis is 0.02% F·S.
关键词： helical tube,pressure,Fabry-Perot cavity,CO2 laser,sensor
更新于2025-09-19 17:15:36
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Coupling of the First and Second Excited States of R6G Dye with the Fabry-Perot Cavity
摘要： Coupling of macroscopic ensembles of highly concentrated R6G molecules with aluminum and silver Fabry–Perot cavities of different sizes, in which one or two standing wave modes are in resonance with the absorption transition(s) of the dye molecules, have been studied. (i) It has been found that strong coupling of the cavity with one molecular eigenstate (S0!S1 transition) does not perturb the energies of the other molecular states. (ii) The S0!S2 absorption transition is too weak to strongly couple to the resonant cavity (“λ” standing wave mode). However, the resonant cavity causes a blue shift of the S0!S2 excitation band. (iii) The splitting of the dispersion curve is theoretically predicted and experimentally observed at strong coupling of the cavity resonance (“λ” standing wave mode) with the material resonances of Ag, including bound electron and “epsilon equal zero” transitions.
关键词： spectroscopy,Fabry–Perot cavity,energy splitting,excited states,spectral shifts,rhodamine 6G dye,strong coupling
更新于2025-09-19 17:15:36
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Converting an organic light-emitting diode from blue to white with Bragg modes
摘要： Organic light-emitting diodes (OLEDs) have been established as versatile light sources that allow for easy integration in large area surfaces and flexible substrates. In addition, the low fabrication cost of OLEDs renders them particularly attractive as general lighting sources. Current methods for the fabrication of white-light OLEDs rely on the combination of multiple organic emitters and/or the incorporation of multiple cavity modes in a thick active medium. These architectures introduce formidable challenges in both device design and performance improvements, namely the decrease of efficiency with increasing brightness (efficiency roll-off) and short operational lifetime. Here we demonstrate, for the first time, white light generation in an OLED consisting of a sub-100 nm-thick blue single emissive layer coupled to the photonic Bragg modes of a dielectric distributed Bragg reflector (DBR). We show that the Bragg modes, although primarily located inside the DBR stack, can significantly overlap with the emissive layer, thus efficiently enhancing emission and outcoupling of photons at selected wavelengths across the entire visible light spectrum. Moreover, we show that color temperature can be tuned by the DBR parameters, offering great versatility in the optimization of white-light emission spectra.
关键词： distributed Bragg reflector,white organic light-emitting diodes (WOLEDs),Fabry-Pérot modes,electroluminescence color conversion,organic semiconductors
更新于2025-09-19 17:13:59
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[IEEE 2019 Joint Conference of the IEEE International Frequency Control Symposium anEuropean Frequency and Time Forum (EFTF/IFC) - Orlando, FL, USA (2019.4.14-2019.4.18)] 2019 Joint Conference of the IEEE International Frequency Control Symposium and European Frequency and Time Forum (EFTF/IFC) - Development of Ultra-stable Clock Laser System for Space Applications
摘要： The National Time Service Centre of China is developing a 698 nm ultra-stable clock laser system for dedicated use in a space strontium optical clock. This report present the development of this system. The laser reaches a frequency instability of 3.5×10?15 at 1 s averaging time and the linewidth is about 1.3 Hz.
关键词： Laser stabilization,Ultra-stable laser,Fabry-Perot
更新于2025-09-19 17:13:59