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Keywords = tapered multimode fiber

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13 pages, 6081 KB  
Article
Sensitivity-Enhanced Temperature Sensor Based on PDMS-Coated Mach–Zehnder Interferometer
by Wenlei Yang, Le Li, Shuo Zhang and Ke Tian
Sensors 2025, 25(4), 1191; https://doi.org/10.3390/s25041191 - 15 Feb 2025
Cited by 4 | Viewed by 1126
Abstract
A sensitivity-enhanced temperature sensor based on a Mach–Zehnder interferometer (MZI) coated by polydimethylsiloxane (PDMS) film is proposed and investigated. The MZI with a compact size of 2.28 mm is fabricated by embedding a tapered single-mode fiber (SMF) between two multimode fibers (MMFs). Since [...] Read more.
A sensitivity-enhanced temperature sensor based on a Mach–Zehnder interferometer (MZI) coated by polydimethylsiloxane (PDMS) film is proposed and investigated. The MZI with a compact size of 2.28 mm is fabricated by embedding a tapered single-mode fiber (SMF) between two multimode fibers (MMFs). Since PDMS has a higher thermo-optical coefficient than silica, the proposed sensor has better temperature sensing performance than the case without PDMS coating, which is demonstrated by simulation and experiment. The experimental results show that the sensitivity of the proposed sensor is as high as −1.06 nm/°C in the range from −5 °C to 45 °C. Full article
(This article belongs to the Special Issue Recent Advances in Micro- and Nanofiber-Optic Sensors)
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12 pages, 6340 KB  
Communication
A Multimode Microfiber Specklegram Biosensor for Measurement of CEACAM5 through AI Diagnosis
by Yuhui Liu, Weihao Lin, Fang Zhao, Yibin Liu, Junhui Sun, Jie Hu, Jialong Li, Jinna Chen, Xuming Zhang, Mang I. Vai, Perry Ping Shum and Liyang Shao
Biosensors 2024, 14(1), 57; https://doi.org/10.3390/bios14010057 - 22 Jan 2024
Cited by 6 | Viewed by 3006
Abstract
Carcinoembryonic antigen (CEACAM5), as a broad-spectrum tumor biomarker, plays a crucial role in analyzing the therapeutic efficacy and progression of cancer. Herein, we propose a novel biosensor based on specklegrams of tapered multimode fiber (MMF) and two-dimensional convolutional neural networks (2D-CNNs) for the [...] Read more.
Carcinoembryonic antigen (CEACAM5), as a broad-spectrum tumor biomarker, plays a crucial role in analyzing the therapeutic efficacy and progression of cancer. Herein, we propose a novel biosensor based on specklegrams of tapered multimode fiber (MMF) and two-dimensional convolutional neural networks (2D-CNNs) for the detection of CEACAM5. The microfiber is modified with CEA antibodies to specifically recognize antigens. The biosensor utilizes the interference effect of tapered MMF to generate highly sensitive specklegrams in response to different CEACAM5 concentrations. A zero mean normalized cross-correlation (ZNCC) function is explored to calculate the image matching degree of the specklegrams. Profiting from the extremely high detection limit of the speckle sensor, variations in the specklegrams of antibody concentrations from 1 to 1000 ng/mL are measured in the experiment. The surface sensitivity of the biosensor is 0.0012 (ng/mL)−1 within a range of 1 to 50 ng/mL. Moreover, a 2D-CNN was introduced to solve the problem of nonlinear detection surface sensitivity variation in a large dynamic range, and in the search for image features to improve evaluation accuracy, achieving more accurate CEACAM5 monitoring, with a maximum detection error of 0.358%. The proposed fiber specklegram biosensing scheme is easy to implement and has great potential in analyzing the postoperative condition of patients. Full article
(This article belongs to the Special Issue Advanced Optical Fiber Sensors for Chemical and Biological Detection)
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22 pages, 8382 KB  
Review
Research Progress in Tunable Fiber Lasers Based on Multimode Interference Filters
by Liqiang Zhang, Kexin Zhu, Yicun Yao, Xiuying Tian, Hailong Xu and Zhaogang Nie
Micromachines 2023, 14(11), 2026; https://doi.org/10.3390/mi14112026 - 30 Oct 2023
Cited by 5 | Viewed by 2953
Abstract
Tunable fiber lasers have the advantages of good beam quality, high integration, and adjustable output wavelength, and they are widely used in fields such as optical fiber communication and optical fiber sensing. The fiber filter is one of the key components of tunable [...] Read more.
Tunable fiber lasers have the advantages of good beam quality, high integration, and adjustable output wavelength, and they are widely used in fields such as optical fiber communication and optical fiber sensing. The fiber filter is one of the key components of tunable fiber lasers. Among the various filters currently used, multimode interference filters have the advantages of simple structure, convenient implementation, flexible tuning methods, and convenient spectral range design. The structures of multimode interference filters based on multimode fibers, no-core fibers, multi-core fibers, tapered fibers, and other special fibers are introduced in this paper. The working principles and tuning methods are analyzed and the research progress of tunable fiber lasers based on these filters is summarized. Finally, the development trend of tunable fiber lasers based on multimode interference filters is discussed. The rapid development and applications of multimode interference filters can help improve the performance of continuous and pulse lasers as well as promote the practicality of tunable fiber lasers. Full article
(This article belongs to the Special Issue High Power Fiber Laser Technology)
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17 pages, 3033 KB  
Article
Confirmation of Dissipative Sensing Enhancement in a Microresonator Using Multimode Input
by Sreekul Raj Rajagopal, Limu Ke, Karleyda Sandoval and Albert T. Rosenberger
Sensors 2023, 23(21), 8700; https://doi.org/10.3390/s23218700 - 25 Oct 2023
Cited by 3 | Viewed by 1110
Abstract
Optical microresonators have proven to be especially useful for sensing applications. In most cases, the sensing mechanism is dispersive, where the resonance frequency of a mode shifts in response to a change in the ambient index of refraction. It is also possible to [...] Read more.
Optical microresonators have proven to be especially useful for sensing applications. In most cases, the sensing mechanism is dispersive, where the resonance frequency of a mode shifts in response to a change in the ambient index of refraction. It is also possible to conduct dissipative sensing, in which absorption by an analyte causes measurable changes in the mode linewidth and in the throughput dip depth. If the mode is overcoupled, the dip depth response can be more sensitive than the linewidth response, but overcoupling is not always easy to achieve. We have recently shown theoretically that using multimode input to the microresonator can enhance the dip-depth sensitivity by a factor of several thousand relative to that of single-mode input and by a factor of nearly 100 compared to the linewidth sensitivity. Here, we experimentally confirm these enhancements using an absorbing dye dissolved in methanol inside a hollow bottle resonator. We review the theory, describe the setup and procedure, detail the fabrication and characterization of an asymmetrically tapered fiber to produce multimode input, and present sensing enhancement results that agree with all the predictions of the theory. Full article
(This article belongs to the Special Issue Feature Papers in Optical Sensors 2023)
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9 pages, 2198 KB  
Article
Relative Humidity Measurement Based on a Tapered, PVA-Coated Fiber Optics Multimode Interference Sensor
by Abraham A. Quiñones-Flores, Jose R. Guzman-Sepulveda and Arturo A. Castillo-Guzman
Optics 2023, 4(3), 473-481; https://doi.org/10.3390/opt4030034 - 31 Jul 2023
Cited by 3 | Viewed by 2448
Abstract
A relative humidity (RH) fiber optic sensor is demonstrated based on the multimode interference (MMI) phenomenon utilizing a no-core fiber (NCF) coated with polyvinyl alcohol (PVA). The sensor’s structure is simple and consists of a section of NCF spliced between two standard single-mode [...] Read more.
A relative humidity (RH) fiber optic sensor is demonstrated based on the multimode interference (MMI) phenomenon utilizing a no-core fiber (NCF) coated with polyvinyl alcohol (PVA). The sensor’s structure is simple and consists of a section of NCF spliced between two standard single-mode fibers (SMFs). The fabrication and testing of a tapered version with enhanced sensitivity is also presented. The native MMI sensor showed a sensitivity of 5.6nm/RH%, in the range from 87 RH% to 93 RH%, while the tapered one exhibited an increased sensitivity of 6.6nm/RH%, in the range from 91.5 RH% to 94 RH%. The sensitivity values obtained with these MMI sensors are at least twice as large as the most sensitive fiber optics humidity sensor reported in the literature in a similar RH range. Full article
(This article belongs to the Special Issue Optical Sensing and Optical Physics Research)
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12 pages, 4582 KB  
Article
Spatially Modulated Fiber Speckle for High-Sensitivity Refractive Index Sensing
by Penglai Guo, Huanhuan Liu, Zhitai Zhou, Jie Hu, Yuntian Wang, Xiaoling Peng, Xun Yuan, Yiqing Shu, Yingfang Zhang, Hong Dang, Guizhen Xu, Aoyan Zhang, Chenlong Xue, Jiaqi Hu, Liyang Shao, Jinna Chen, Jianqing Li and Perry Ping Shum
Sensors 2023, 23(15), 6814; https://doi.org/10.3390/s23156814 - 31 Jul 2023
Cited by 4 | Viewed by 2579
Abstract
A fiber speckle sensor (FSS) based on a tapered multimode fiber (TMMF) has been developed to measure liquid analyte refractive index (RI) in this work. By the lateral and axial offset of input light into TMMF, several high-order modes are excited in TMMF, [...] Read more.
A fiber speckle sensor (FSS) based on a tapered multimode fiber (TMMF) has been developed to measure liquid analyte refractive index (RI) in this work. By the lateral and axial offset of input light into TMMF, several high-order modes are excited in TMMF, and the speckle pattern is spatially modulated, which affects an asymmetrical speckle pattern with a random intensity distribution at the output of TMMF. When the TMMF is immersed in the liquid analyte with RI variation, it influences the guided modes, as well as the mode interference, in TMMF. A digital image correlations method with zero-mean normalized cross-correlation coefficient is explored to digitize the speckle image differences, analyzing the RI variation. It is found that the lateral- and axial-offsets-induced speckle sensor can enhance the RI sensitivity from 6.41 to 19.52 RIU−1 compared to the one without offset. The developed TMMF speckle sensor shows an RI resolution of 5.84 × 10−5 over a linear response range of 1.3164 to 1.3588 at 1550 nm. The experimental results indicate the FSS provides a simple, efficient, and economic approach to RI sensing, which exhibits an enormous potential in the image-based ocean-sensing application. Full article
(This article belongs to the Special Issue Research Progress and Applications of Distributed Optical Fiber Sensing)
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16 pages, 2512 KB  
Article
Downtaper on Multimode Fibers towards Sustainable Power over Fiber Systems
by Alicia Fresno-Hernández, Marta Rodríguez-Guerra, Roberto Rodríguez-Garrido and Carmen Vázquez
Photonics 2023, 10(5), 513; https://doi.org/10.3390/photonics10050513 - 28 Apr 2023
Cited by 3 | Viewed by 2364
Abstract
This paper presents a transition taper for coupling light between optical fibers with different geometries and refractive index profiles used in Power over Fiber (PoF) systems. Global energy efficiency and costs are critical parameters when delivering high power to remote areas. High-power lasers [...] Read more.
This paper presents a transition taper for coupling light between optical fibers with different geometries and refractive index profiles used in Power over Fiber (PoF) systems. Global energy efficiency and costs are critical parameters when delivering high power to remote areas. High-power lasers have maximum coupling for large core fibers, while widespread multimode optical (OM1) fibers used in optical communications are cheaper. We study the optical losses between large core fibers (200 µm) and OM1 fibers (62.5 µm) theoretically and experimentally. We demonstrate that improvements of 2 dB can be obtained by adding the new tapered structure to the system, compared to the direct splice between both fibers. There is good agreement between measured and calculated loss values using a new Gaussian loss model to describe splices between tapered and straight fibers. The fabrication of the transition taper is also described. We also measure the numerical aperture (NA) changes in the downtaper zone and demonstrate that the lower the NA of the input light, the higher the efficiency improvement. Full article
(This article belongs to the Special Issue Latest Papers Related to OWPT 2023 on the Topics of Devices, Components and Systems)
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12 pages, 3169 KB  
Communication
Design of a Broadband Fiber Optic Mode Coupler for Multimode Optical Coherence Tomography
by Dora Juan Juan Hu, Linbo Liu, Hui Dong and Hailiang Zhang
Photonics 2023, 10(2), 162; https://doi.org/10.3390/photonics10020162 - 3 Feb 2023
Cited by 1 | Viewed by 4021
Abstract
In this paper, we propose an optical fiber-based broadband mode coupler for multimode optical coherence tomography (OCT) in the O-band (1.26–1.36 μm). The proposed device uses a tapered few-mode fiber (FMF) to lower the effective mode index of the selected higher-order mode, which [...] Read more.
In this paper, we propose an optical fiber-based broadband mode coupler for multimode optical coherence tomography (OCT) in the O-band (1.26–1.36 μm). The proposed device uses a tapered few-mode fiber (FMF) to lower the effective mode index of the selected higher-order mode, which can be phase matched to the fundamental mode of the single-mode fiber (SMF). The tapered FMF and the SMF are side polished to reduce the core-to-core separation to achieve efficient mode coupling. Key design parameters such as the tapering ratio of the FMF, FMF core to SMF core separation, coupler length, and coupling ratio in the O-band are studied thoroughly. Higher-order modes of the FMF will be effectively coupled from the fundamental mode of SMF in the sample arm of the multimode OCT system. The reflected signals of the higher-order modes from the sample will be separated into several single-mode signals using the same fiber device before interfering with the reference light, which was not possible before. The proposed fiber device will be a key component to efficiently achieve multimode OCT operation with better signal collection efficiency and improved penetration depth for deep tissue imaging. Full article
(This article belongs to the Special Issue Advances in 3OM: Opto-Mechatronics, Opto-Mechanics, and Optical Metrology)
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6 pages, 1595 KB  
Communication
High-Performance Microwave Photonic Transmission Enabled by an Adapter for Fundamental Mode in MMFs
by Yilan Wang, Linbo Yang, Zhiqun Yang, Yaping Liu, Zhanhua Huang and Lin Zhang
Appl. Sci. 2023, 13(3), 1794; https://doi.org/10.3390/app13031794 - 30 Jan 2023
Cited by 1 | Viewed by 1753
Abstract
Microwave photonic links (MPLs) have long been considered as an excellent way for radio frequency (RF) transmission due to their advantages such as light weight, high bandwidth, low cost and large spurious-free dynamic range (SFDR). However, the effective mode-field area (Aeff) [...] Read more.
Microwave photonic links (MPLs) have long been considered as an excellent way for radio frequency (RF) transmission due to their advantages such as light weight, high bandwidth, low cost and large spurious-free dynamic range (SFDR). However, the effective mode-field area (Aeff) of the single-mode fiber (SMF) used in the traditional MPL is not large, so the MPL based on SMF have relatively strong nonlinearity, which limits the processing power of SMFs to a level of few milliwatts. Few-mode fibers (FMFs) have been applied in MPL as an alternative due to the larger Aeff, and photonic lanterns are used simultaneously to excite the high-order mode of FMFs for RF signal transmission. However, the photonic lantern could bring additional insertion loss, and the production cost of FMFs is high, so we propose an MPL based on multimode fibers (MMFs) with mode field adapters (MFAs). Since MMFs have larger Aeff, the nonlinearity of the link can be greatly reduced. And matched MFAs realized by reverse tapering, to excite only the fundamental mode in MMFs to reduce the crosstalk, which are very stable. As a result, the stimulated Brillouin scattering threshold and SFDR are improved by 5 dB and 14.5 dB, respectively. Full article
(This article belongs to the Special Issue Advancements in Wireless Communications, Networks and Signal Processing)
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10 pages, 2565 KB  
Article
Sub-Nanometer Acoustic Vibration Sensing Using a Tapered-Tip Optical Fiber Microcantilever
by Chunyu Lu, Mahdi Mozdoor Dashtabi, Hamed Nikbakht, Mohammad Talebi Khoshmehr and B. Imran Akca
Sensors 2023, 23(2), 924; https://doi.org/10.3390/s23020924 - 13 Jan 2023
Cited by 7 | Viewed by 3203
Abstract
We demonstrate a highly sensitive acoustic vibration sensor based on a tapered-tip optical fiber acting as a microcantilever. The tapered-tip fiber has a unique output profile that exhibits a circular fringe pattern, whose distribution is highly sensitive to the vibration of the fiber [...] Read more.
We demonstrate a highly sensitive acoustic vibration sensor based on a tapered-tip optical fiber acting as a microcantilever. The tapered-tip fiber has a unique output profile that exhibits a circular fringe pattern, whose distribution is highly sensitive to the vibration of the fiber tip. A piezo transducer is used for the acoustic excitation of the fiber microcantilever, which results in a periodic bending of the tip and thereby a significant output power modulation. Using a multimode readout fiber connected to an electric spectrum analyzer, we measured the amplitude of these power modulations over the 10–50 kHz range and observed resonances over certain frequency ranges. Two types of tapered-tip fibers were fabricated with diameter values of 1.5 µm and 1.8 µm and their frequency responses were compared with a non-tapered fiber tip. Thanks to the resonance effect as well as the sensitive fringe pattern of the tapered-tip fibers, the limit of detection and the sensitivity of the fiber sensor were obtained as 0.1 nm and 15.7 V/nm, respectively, which were significantly better than the values obtained with the non-tapered fiber tip (i.e., 1.1 nm and 0.12 V/nm, respectively). The sensor is highly sensitive, easy to fabricate, low-cost, and can detect sub-nanometer displacements, which makes it a promising tool for vibration sensing, particularly in the photoacoustic sensing of greenhouse gases. Full article
(This article belongs to the Special Issue New Prospects in Fiber Optic Sensors and Applications)
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19 pages, 8732 KB  
Article
Palladium/Graphene Oxide Nanocomposite for Hydrogen Gas Sensing Applications Based on Tapered Optical Fiber
by Mohammed Majeed Alkhabet, Zaher Mundher Yaseen, Moutaz Mustafa A. Eldirderi, Khaled Mohamed Khedher, Ali H. Jawad, Saad Hayatu Girei, Husam Khalaf Salih, Suriati Paiman, Norhana Arsad, Mohd Adzir Mahdi and Mohd Hanif Yaacob
Materials 2022, 15(22), 8167; https://doi.org/10.3390/ma15228167 - 17 Nov 2022
Cited by 16 | Viewed by 3720
Abstract
Gaseous pollutants such as hydrogen gas (H2) are emitted in daily human activities. They have been massively studied owing to their high explosivity and widespread usage in many domains. The current research is designed to analyse optical fiber-based H2 gas [...] Read more.
Gaseous pollutants such as hydrogen gas (H2) are emitted in daily human activities. They have been massively studied owing to their high explosivity and widespread usage in many domains. The current research is designed to analyse optical fiber-based H2 gas sensors by incorporating palladium/graphene oxide (Pd/GO) nanocomposite coating as sensing layers. The fabricated multimode silica fiber (MMF) sensors were used as a transducing platform. The tapering process is essential to improve the sensitivity to the environment through the interaction of the evanescent field over the area of the tapered surface area. Several characterization methods including FESEM, EDX, AFM, and XRD were adopted to examine the structure properties of the materials and achieve more understandable facts about their functional performance of the optical sensor. Characterisation results demonstrated structures with a higher surface for analyte gas reaction to the optical sensor performance. Results indicated an observed increment in the Pd/GO nanocomposite-based sensor responses subjected to the H2 concentrations increased from 0.125% to 2.00%. The achieved sensitivities were 33.22/vol% with a response time of 48 s and recovery time of 7 min. The developed optical fiber sensors achieved excellent selectivity and stability toward H2 gas upon exposure to other gases such as ammonia and methane. Full article
(This article belongs to the Special Issue Advanced Materials for Optical Fibers)
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9 pages, 2702 KB  
Communication
Designation of Pump-Signal Combiner with Negligible Beam Quality Degradation for a 15 kW Tandem-Pumping Fiber Amplifier
by Zhixian Li, Min Fu, Hu Xiao, Zilun Chen, Zefeng Wang and Jinbao Chen
Photonics 2022, 9(9), 644; https://doi.org/10.3390/photonics9090644 - 8 Sep 2022
Cited by 7 | Viewed by 2788
Abstract
In this paper, the fabrication method of a pump/signal (6 + 1) × 1 combiner based on a large-core (48 μm) multimode signal fiber is introduced. Since the signal fiber is not tapered in the production, and an effective feedback alignment method is [...] Read more.
In this paper, the fabrication method of a pump/signal (6 + 1) × 1 combiner based on a large-core (48 μm) multimode signal fiber is introduced. Since the signal fiber is not tapered in the production, and an effective feedback alignment method is adopted during the splice process, the degradation ratio of the M2 value of the signal light is only about 5% after passing through the beam combiner. In addition, with the help of a home-made beam combiner, a counter-directional tandem-pumping amplifier is built. The maximum output power of the amplifier is 15.31 kW with the slope efficiency of 83.2%. The temperature rise coefficient of the home-made combiner is 3.2 °C/kW and the backward isolation degree is more than 36 dB from each pump pigtail. Both test results prove the outstanding potential of the pump-signal combiner in high-power laser applications. Full article
(This article belongs to the Section Lasers, Light Sources and Sensors)
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12 pages, 3136 KB  
Article
Silicon Oxynitride Thin Film Coating to Lossy Mode Resonance Fiber-Optic Refractometer
by Dmitriy P. Sudas, Leonid Yu. Zakharov, Viktor A. Jitov and Konstantin M. Golant
Sensors 2022, 22(10), 3665; https://doi.org/10.3390/s22103665 - 11 May 2022
Cited by 9 | Viewed by 3381
Abstract
A fiber-optic refractometer for various liquids with refractive indices in the range from 1.33 to 1.43 has been manufactured and tested. The sensor is based on a thin silicon oxynitride (Si3N4-xOx) film coated thinned optic fiber section [...] Read more.
A fiber-optic refractometer for various liquids with refractive indices in the range from 1.33 to 1.43 has been manufactured and tested. The sensor is based on a thin silicon oxynitride (Si3N4-xOx) film coated thinned optic fiber section (taper) obtained in a multimode all-silica optical fiber by chemical etching of the reflective cladding. The film was deposited on the cylindrical surface of the thinned fiber by the surface plasma chemical vapor deposition method (SPCVD). Lossy mode resonance (LMR) was observed in the transmission spectrum of the coated taper at a wavelength dependent on the refractive index of the liquid in which the taper was immersed. We tested the obtained sensors in distilled water, isopropyl alcohol, dimethylformamide, and their aqueous solutions. It was found that with the help of the SPCVD, one can obtain a set of sensors in a single deposition run with the dispersion of sensitivity and spectral position of LMR no more than 5%. Maximum sensitivity of the manufactured sensors to surrounding media refractive index (SMRI) variation exceeds 1090 nm/RIU, which is the highest value recorded to date for a sensor with a non-oxide coating. Full article
(This article belongs to the Special Issue State-of-the-Art Optical Sensors Technology in Russia 2021-2022)
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8 pages, 2591 KB  
Proceeding Paper
Tapered Optical Fiber for Hydrogen Sensing Application Based on Molybdenum Trioxide (MoO3)
by Mohammed Majeed Alkhabet, Saad Hayatu Girei, Suriati Paiman, Norhana Arsad, Mohd Adzir Mahdi and Mohd Hanif Yaacob
Eng. Proc. 2021, 10(1), 75; https://doi.org/10.3390/ecsa-8-11315 - 1 Nov 2021
Cited by 6 | Viewed by 2197
Abstract
In this work, molybdenum trioxide (MoO3) was synthesized and deposited on tapered optical fiber using the drop-casting technique for hydrogen (H2) detection at room temperature. A transducing platform in a transmission mode was constructed using multimode optical fiber (MMF) [...] Read more.
In this work, molybdenum trioxide (MoO3) was synthesized and deposited on tapered optical fiber using the drop-casting technique for hydrogen (H2) detection at room temperature. A transducing platform in a transmission mode was constructed using multimode optical fiber (MMF) with a 125 µm cladding and a 62.5 µm core diameter. To enhance the evanescent light field surrounding the fiber, the fibers were tapered from 125 µm in diameter to 20 µm in diameter with a 10 mm waist. The microstructures and chemical compositions of the fabricated sensor were analyzed by field emission scanning electron microscopy (FESEM), energy dispersive X-ray (EDX), differential X-ray (XRD), and atomic force microscopy (AFM). In addition, the gas detection properties of the fabricated sensor were studied by exposing it to various concentrations of hydrogen gas from 0.125% to 2.00%. As a result, the sensitivity, response, and recovery time were 11.96 vol%, 220 s, and 200 s, respectively. Overall, the fabricated sensor exhibits good sensitivity as well as repeatability and stability for hydrogen gas detection. Full article
(This article belongs to the Proceedings of The 8th International Electronic Conference on Sensors and Applications)
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10 pages, 34656 KB  
Communication
Spatial Beam Self-Cleaning in Bi-Tapered Multimode Fibers
by Xiao-Jun Lin, Yu-Xin Gao, Jin-Gan Long, Jia-Wen Wu, Xiang-Yue Li, Wei-Yi Hong, Hu Cui, Zhi-Chao Luo, Wen-Cheng Xu and Ai-Ping Luo
Photonics 2021, 8(11), 479; https://doi.org/10.3390/photonics8110479 - 27 Oct 2021
Cited by 2 | Viewed by 2987
Abstract
We report the spatial beam self-cleaning in bi-tapered conventional multimode fibers (MMFs) with different tapered lengths. Through the introduction of the bi-tapered structure in MMFs, the input beam with poor beam quality from a high-power fiber laser can be converted to a centered, [...] Read more.
We report the spatial beam self-cleaning in bi-tapered conventional multimode fibers (MMFs) with different tapered lengths. Through the introduction of the bi-tapered structure in MMFs, the input beam with poor beam quality from a high-power fiber laser can be converted to a centered, bell-shaped beam in a short length, due to the strengthened nonlinear modes coupling. It is found that the bi-tapered MMF with longer tapered length at the same waist diameter shows better beam self-cleaning effect and larger spectral broadening. The obtained results offer a new method to improve the beam quality of high-power laser at low cost. Furthermore, it may be interesting for manufacturing bi-tapered MMF-based devices to obtain the quasi-fundamental mode beam in spatiotemporal mode-locked fiber lasers. Full article
(This article belongs to the Special Issue Specialty Optical Fibers, Fiber Lasers and Their Applications)
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