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Low-power-consumption Fiber-optic Anemometer based on Long-period Grating with SWCNT Coating
摘要： We report a low-power-consumption fiber-optic 'hot wire' anemometer (HWA) based on long-period grating (LPG) with single-wall carbon nanotubes (SWCNTs) coating. A uniform SWCNT film is deposited on a bare LPG acting as both light coupling and sensing element. By carefully selecting the order of the cladding mode and operating wavelength, the LPG shows a much higher temperature sensitivity than that of a regular fiber Bragg grating (FBG). Besides, SWCNT is a single-wall cylindrical nanostructure material with excellent absorption in the infrared range and high thermal conductivity. Due to these two features, the proposed sensor has extremely low power consumption and simple operation by utilizing a broadband light source (BBS) as both heating source and probing light source. A sensitivity of 102.5 pm/(m/s) at the wind speed of 1 m/s was obtained experimentally with 1.6-μm-thick SWCNT film.
关键词： Temperature.,Fiber-optic anemometer,long-period fiber grating,Carbon nanotube
更新于2025-09-23 15:23:52
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Torsion‐dependent spectral response of long‐period fiber grating based on electric arc technique with axial rotation of the fiber
摘要： We present a novel technique for manufacturing a long-period fiber grating (LPFG) with enhanced torsion sensitivity based on electric arc technique. The proposed method rotates the fiber around its axis of rotation at each electric arc discharge. We experimentally investigated the torsion-dependent spectral response of the produced grating and the results showed that an enhanced linear torsion sensitivity up to 0.197 nm/(rad/m) was achieved, which is higher than that of the conventional arc-induced LPFGs.
关键词： long-period fiber grating,torsion sensing,electric arc discharge
更新于2025-09-23 15:23:52
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Graphene induced sensitivity enhancement of thin-film coated long period fiber grating
摘要： In this work, the tuning property and sensitivity enhancement of the long period fiber grating (LPFG) coated with the higher refractive index film are demonstrated theoretically by integrating a monolayer graphene. The general variation rule of the mode characteristics and the resonance with the chemical potential of the graphene are explored. The polarization-independent transmission and sensing characteristics are obtained even though the optical property of the graphene is polarization-dependent. The results reveal that the sensing characteristics are significantly dependent on the tunable state of the graphene, which can be used to greatly optimize the sensing performance. By this approach, an ultrahigh sensitivity up to 28 337.5 nm/RIU is achieved, which is 2:57 times higher than that of the conventional LPFG without graphene. The sensitivity can be further optimized by integrating few-layer graphene. This tunable property at a wide range makes the graphene integrated LPFG devices without destroying the fiber integrity ideal for wide applications, such as biochemical sensing and optical modulation.
关键词： graphene,long period fiber grating,optical modulation,sensitivity enhancement,tunable property
更新于2025-09-23 15:21:01
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A micro MMF layer embedded in LPFG for simultaneous measurement of curvature and temperature
摘要： A micro multimode fiber (MMF) layer embedded in long period fiber grating (ME-LPFG) has been developed and experimentally investigated for the simultaneous measurement of curvature and temperature. The LPFG is written by using high-frequency CO2 laser pulses. The transmission spectrum of the novel LPFG can show the wavelength shift and splitting characteristics relative to the original LPFG. The wavelengths of the two resonant peak changes are used to monitor the variations of the curvature and temperature due to different responses. The experimental results show that the curvature sensitivities of the two peaks are -7.056 nm/m-1 and -21.080 nm/m-1, respectively. The curvature sensitivity is bigger than that of the common LPFG. And the temperature sensitivities of the two peaks reach 60 pm/°C and 58 pm/°C, respectively. Therefore the ME-LPFG has the potential to measure the curvature and temperature simultaneously with the resolutions of 4.7 × 10-5 m-1 and 0.3 °C.
关键词： Long period fiber grating,Temperature,Simultaneous measurement,Curvature
更新于2025-09-19 17:15:36
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Stable generation of orbital angular momentum mode with an all-fiber laser
摘要： In this paper, an all-fiber laser that can generate stable OAM modes with topological charges of ±1 is demonstrated. A ring-core fiber designed in-house is used to reduce the crosstalk between OAM mode and other modes. A ring-core fiber-based long-period fiber grating (LPFG) and a fiber Bragg grating (FBG) are employed to select desired OAM mode. The coupling ratio of LPFG from HE11 mode to OAM mode exceeds 16 dB, and the mode purity of ±1 is demonstrated. The purity of OAM mode is as high as 94.41%. This simple and compact fiber laser can be integrated into fiber-based OAM mode multiplexing optical communication system.
关键词： orbital angular momentum,fiber Bragg grating,ring-core fiber,long-period fiber grating,all-fiber laser
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - The fabrication mechanism and spectral characteristics of Fiber Gratings fabricated by point-by-point direct-writing based on femtosecond laser pulses
摘要： In this paper, a series of fiber gratings with different spectrum characteristics are fabricated in standard telecommunication fiber without hydrogen loading by point-by-point direct writing method based on 100 femtosecond laser amplifier system at 800-nm central wavelength. They are including the fourth-order fiber Bragg grating, fiber Bragg grating Fabry-Perot cavity, sampling fiber Bragg grating and cascaded long period fiber grating. The experimental results show that the spectrum characteristics of fourth-order fiber Bragg gratings with Λ=1.93 μm period are obtained at the center wavelength λ=1394.5 nm, and the fiber Bragg grating Fabry-Perot cavity can be inscribed when the gating period is Λ=1.95 μm. Furthermore, the sampled fiber Bragg gratings with different sampled periods are fabricated by adjusting the sampling period. Finally, the spectrum of the cascaded long period fiber gratings is achieved by changing the grating pitch of long period grating with 3 mm, 5 mm and 7 mm, respectively. This study will provide a powerful experimental gist and theoretical basis for the fabrication of different types of fiber gratings by femtosecond laser point-by-point writing directly method.
关键词： fiber Bragg gratings (FBGs),sampled fiber Bragg grating (S-FBG),point-by-point (PBP) direct-writing method,cascaded long period fiber grating(C-LPFG)
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Fabrication and sensing characteristics of 2 μm long period fiber grating written in double cladding fiber by CO <sub/>2</sub> laser
摘要： We demonstrate the fabrication of long period fiber gratings (LPFGs) in double cladding fiber in mid-infrared wavelength. The experimental results show that the LPFGs with a resonance dip in mid-infrared wavelength have much higher sensitivity.
关键词： double cladding fiber,fiber sensor,Long-period fiber grating
更新于2025-09-16 10:30:52
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ESSE 2017 (Proceedings of the International Conference on Environmental Science and Sustainable EnergyEd.by ZhaoYang Dong) || Transverse-Load Characteristics of Long Period Fiber Gratings Fabricated By Femtosecond Laser Pulses
摘要： The transverse-load characteristics of long period fiber gratings (LPFGs) fabricated by 800 nm femtosecond laser are demonstrated and investigated. It is observed that the resonant wavelength of LPFG is dependent on the direction of applied force. When a transverse load is applied along different orientations of the LPFG, the resonant wavelength will experience red shift or blue shift. However, the transmission attenuation is gradually decreases as the applied transverse-load increases, which is independent of the direction of applied force. This is mainly due to the asymmetrical distribution of the refractive index on the cross-section of LPFG induced by femtosecond laser pulses, the load-induced birefringence lead to the rotation of optical principal axes in the LPFG.
关键词： long period fiber grating,transverse-load characteristics,femtosecond laser
更新于2025-09-16 10:30:52
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Layer-by-layer assembly of polyelectrolytes-wrapped multi-walled carbon nanotubes on long period fiber grating sensors
摘要： A new type of long period fiber grating (LPG) sensor coated with polyelectrolytes-wrapped multi-walled carbon nanotube (MWCNT) (PE-CNT) thin film is reported in this study. The novel morphologies of the MWCNT-based nanostructured thin film are observed by scanning electron microscopy characterization. The refractive index and pH sensing behaviors of LPGs with pure (PE)10 thin film and with (PE-CNT)10 thin film, respectively are compared. Results show that for LPG with (PE-CNT)10 thin film the transmission intensity at the resonance wavelength decreases noticeably with the increase of the surrounding refractive index. This is distinct from the sensing mechanism of LPG with (PE)10 thin film, which is based on the resonance wavelength shift. The LPG with a (PE-CNT)10 thin film provides enhanced pH sensitivity compared with that of a (PE)10 thin film. The LPG with (PE-CNT)10 thin film has a fast response rate and a good repeatability, thus demonstrating its strong potentiality for practical monitoring applications.
关键词： layer-by-layer assembly,sensor,thin film,Long period fiber grating,pH sensing,carbon nanotube
更新于2025-09-11 14:15:04
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Simultaneous measurement of refractive index and temperature based on a long period fiber grating inscribed in a photonic crystal fiber with an electric-arc discharge
摘要： A novel fiber sensor composed by two single mode fibers and long period fiber grating based on a photonic crystal fiber prepared by periodic discharge heating has been experimentally investigated to measure refractive index and temperature. A Mach-Zehnder interferometer was formed due to the presence of two fusion spliced collapsed regions in the photonic crystal fiber. The resonance dip and interference pattern were differently influenced by the ambient disturbance, so the dual-parameters were simultaneously measured by analyzing the characteristics of transmission spectrum. After the experimental measurements, refractive index and temperature sensitivities of 117.28 nm/RIU and (cid:1)86.29 pm/(cid:3)C were realized. Therefore, the reported sensor with advantages of easy fabrication, simple structure, and small size has the potential for simultaneous refractive index and temperature measurements involving biochemical sensing applications.
关键词： simultaneous measurement,photonic crystal fiber,refractive index and temperature,Long period fiber grating
更新于2025-09-04 15:30:14