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2nd-order random lasing in a multimode diode-pumped graded-index fiber
摘要： Raman lasing in a graded-index fiber (GIF) attracts now great deal of attention due to the opportunity to convert high-power multimode laser diode radiation into the Stokes wave with beam quality improvement based on the Raman clean-up effect. Here we report on the cascaded Raman generation of the 2nd Stokes order in the 1.1-km long GIF with 100-μm core directly pumped by 915-nm diodes. In the studied all-fiber scheme, the 1st Stokes order is generated at 950–954 nm in a linear cavity formed at GIF ends by two fiber Bragg gratings (FBGs) securing beam quality improvement from M2 ≈ 30 to M2 ≈ 2.3 due to special transverse structure of FBGs. The 2nd Stokes wave is generated either in linear (two FBGs) or half-open (one FBG) cavity with random distributed feedback via Rayleigh backscattering. Their comparison shows that the random lasing provides better beam quality and higher slope efficiency. Nearly diffraction limited beam (M2 ≈ 1.6) with power up to 27 W at maximum gain (996 nm), and 17 W at the detuned wavelength of 978 nm has been obtained, thus demonstrating that the 2nd-order random lasing in diode-pumped GIF with FBGs provides high-efficiency high-quality beam generation in a broad wavelength range within the Raman gain spectral profile.
关键词： laser diode,fiber Bragg gratings,beam quality,graded-index fiber,Raman lasing,random distributed feedback
更新于2025-09-23 15:21:21
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[OSA Optical Fiber Sensors - Lausanne (2018..-..)] 26th International Conference on Optical Fiber Sensors - Thermal and Residual Strain Response of an FBG-Based Temperature Sensor Embedded in Carbon Fiber Reinforced Composites
摘要： A strain-free temperature sensor based on a fiber Bragg grating loosely embedded in carbon fiber reinforced polymers is investigated. The effects of different anti-stick materials for packaging on the temperature and residual-strain responses are evaluated.
关键词： Fiber optics sensors,Fiber Bragg gratings
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE International Electron Devices Meeting (IEDM) - San Francisco, CA, USA (2019.12.7-2019.12.11)] 2019 IEEE International Electron Devices Meeting (IEDM) - Demonstration of BEOL-compatible ferroelectric Hf <sub/>0.5</sub> Zr <sub/>0.5</sub> O <sub/>2</sub> scaled FeRAM co-integrated with 130nm CMOS for embedded NVM applications
摘要： We present a phase mask inscription technique with two beam interferometry using a lateral nonhomogeneous beam splitter to create gratings with nonhomogeneous periods, the so-called chirped fiber Bragg gratings. Inscription experiments with deep ultraviolet excimer and femtosecond laser sources reveal how this inscription method depends on the coherence properties of the inscription laser. Nonhomogeneous beam splitters are shown to provide a method to generate chirped fiber Bragg gratings with great wavelength versatility, even with the ultraviolet femtosecond laser.
关键词： Femtosecond laser,optical fiber filters,two-beam interferometry,fiber Bragg gratings
更新于2025-09-23 15:21:01
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Multiple Parameters Optical Sensing Using Fiber Ring Laser Based on Fiber Bragg Gratings and 1064 nm Semiconductor Optical Amplifier
摘要： In this paper, a semiconductor optical amplifier (SOA) based 1064 nm fiber ring laser with 63.56 dB optical signal-to-noise ratio (OSNR) is demonstrated. The stable performance is measured for six hours with lasing peak variation of ≤±0.115 dB and wavelength variation of ≤±0.006 nm. Combining the fiber ring laser with fiber Bragg gratings (FBGs), the SOA based fiber ring laser is applied to sense stretch, squeeze, and temperature variation. The results show high linearity, which is suitable for interpolation method prediction and evaluation. A large dynamic range of up to 10 km is also demonstrated for remote sensing applications.
关键词： optical amplifier,fiber Bragg gratings,fiber ring laser,multiple parameters,semiconductor optical amplifier
更新于2025-09-23 15:21:01
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Polymer Fiber Optic Sensors – A Mini Review of their Synthesis and Applications
摘要： Fiber optic sensors (FOSs) are optical fiber based sensing devices that have been widely used to detect physical, chemical and biological parameters. Polymer optical fibers (POFs), an important type of optical fibers, have been stifled their talents in the field of optical sensing due to the overwhelming popularity of glass optical fibers (GOFs). The unique physical and chemical properties of POFs start attracting interests to be utilized in the fabrication of high performance sensors in recent years. This article reviews the recent progress of POFs based FOSs. In particular, the article will focus on novel techniques implemented on the POF sensor fabrication, including monolayer graphene, evanescent wave absorption, localized surface plasmon resonance and fiber Bragg grating.
关键词： Localized surface plasmon resonance,Fiber Bragg gratings,Evanescent wave,Microstructured polymer optical fiber,Polymer fiber optic sensor
更新于2025-09-23 15:21:01
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Integrated Optical Add-Drop Multiplexer in SOI Based on Mode Selection and Bragg Reflection
摘要： We present a compact optical add-drop multiplexer in silicon-on-insulator based on combining mode selection with Bragg reflection. The add-drop channel has a 3-dB bandwidth of 2 nm, an extinction ratio of 30 dB, and an interferometric crosstalk of less than –42 dB. We characterize the inter-channel and interferometric crosstalk performance using BER measurements for 10-Gb/s NRZ data and obtain crosstalk induced power penalties less than 3.5 dB.
关键词： silicon-on-insulator,Bragg gratings,multi-mode waveguides,Optical add-drop multiplexer
更新于2025-09-23 15:21:01
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Design for Hybrid Circular Bragg Gratings for a Highly Efficient Quantum-Dot Single-Photon Source
摘要： We present a design for hybrid circular Bragg gratings (hCBGs) for efficiently extracting single-photons emitted by InAs quantum dots (QDs) embedded in GaAs. Finite-difference time-domain simulations show that a very high photon collection efficiency (PCE) up to 96% over a 50 nm bandwidth and pronounced Purcell factors up to 19 at cavity resonance are obtained. We also systematically investigate the geometry parameters, including the SiO2 thickness, grating period, gap width and the central disk radius, to improve the device performances. Finally, the PCEs and the Purcell factors of QDs located at different positions of the hCBG are studied, and the results show great robustness against uncertainties in the location of the QD.
关键词： Semiconductor quantum dots,Circular Bragg gratings,Single-photon source
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Environmentally Friendly Method for Synthesizing Reduced Graphene Oxide (rGO) for Transparent Conductive Electrode (TCE) in Solar Cells
摘要： We present a phase mask inscription technique with two beam interferometry using a lateral nonhomogeneous beam splitter to create gratings with nonhomogeneous periods, the so-called chirped fiber Bragg gratings. Inscription experiments with deep ultraviolet excimer and femtosecond laser sources reveal how this inscription method depends on the coherence properties of the inscription laser. Nonhomogeneous beam splitters are shown to provide a method to generate chirped fiber Bragg gratings with great wavelength versatility, even with the ultraviolet femtosecond laser.
关键词： Femtosecond laser,optical fiber filters,two-beam interferometry,fiber Bragg gratings
更新于2025-09-23 15:19:57
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Femtosecond laser direct written off-axis fiber Bragg gratings for sensing applications
摘要： First order off-axis fiber Bragg gratings (FBGs) were fabricated in a standard single mode fiber (SMF-28e) through femtosecond laser direct writing. A minimum offset distance between the grating and core center of 2.5 μm was found to create a multimode section, which supports two separate fiber modes (LP0,1 and LP1,1), each split into two degenerate polarization modes. The resulting structure breaks the cylindrical symmetry of the fiber, introducing birefringence (≈10?4) resulting in a polarization dependent Bragg wavelength for each mode. Based on the modal and birefringence behavior, three off-axis FBGs were fabricated with 3.0, 4.5 and 6.0 μm offsets from the core center, and then characterized in strain, temperature, and curvature. The tested off-axis FBGs exhibited a similar strain sensitivity of ~1.14 pm/μ? and a temperature sensitivity of ~12 pm/C. The curvature and orientation angle were simultaneously monitored by analyzing the intensity fluctuation and the wavelength shift of the LP1,1 Bragg resonance. A maximum curvature sensitivity of 0.53 dB/m?1 was obtained for the off-axis FBG with a 3.0 μm offset.
关键词： optical fiber sensors,femtosecond laser direct writing,single mode fiber,off-axis fiber Bragg gratings,Birefringence
更新于2025-09-23 15:19:57
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Fiber Bragg Grating-Based Oil-Film Pressure Measurement in Journal Bearings
摘要： The on-line measurement of oil-film pressure inside a journal bearing based on an optical fiber Bragg grating (FBG) is proposed and described for the first time. Two methods are described, one includes inserting the packaged FBG into the bearing using rubber and the other is involved the packaged FBG being directly embedded on the bearing surface. The inserted method has a higher sensitivity than the embedded version, while the embedded method incurs less damage to the bearing being small in size. Experiments to verify the feasibility of both methods are described with parameters being measured over the full motor operating range. Experimental results of the oil film pressure measured by these two methods agree well with simulated values, demonstrating excellent prospects for using the sensing schemes described in this paper as the basis for real industrial measurement systems. Furthermore, due to its small size and high sensitivity, coupled with excellent immunity to external electromagnetic interference the FBG sensor is an ideal candidate for measurement in which a strong electromagnetic field exists, e.g., in the case of electrical motors and generators.
关键词： temperature compensation,optical fiber sensors,oil film,pressure measurement,Fiber Bragg gratings (FBGs)
更新于2025-09-19 17:15:36