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Polarization induced non-reciprocal phase controlled all-fiber loop mirror based inclinometer
摘要： An optical fiber inclinometer based on non-reciprocal phase change effect in a single-mode fiber loop mirror (FLM) is proposed. The phase of light waves in FLM is controlled by two-phase shifters (PSs). The relationship between the inclination angles and phase differences of the two-PSs, and transmitted light power was derived by Jones calculus. The signature of the birefringence obtained through simulation on the output light has been confirmed by experimentation. From the results, it was found that when the birefringence of the two-PSs are different, two measurement sensitivities (17.07 × 10?3 deg?1 and 21.37 × 10?3 deg?1) can be realized with one angle measurement system. We also report a method for changing measurable ranges, and measurement sensitivity. Since the angle can be directly measured from the transmitted light power, the results of this work contribute to the realization of simple and low-loss inclinometers using standard single-mode fiber.
关键词： Optical fiber inclinometer,Tilt measurement,Fiber optics,Sagnac interferometer,Fiber loop mirror
更新于2025-11-28 14:24:03
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A single-longitudinal-mode narrow-linewidth dual-wavelength fiber laser using a microfiber knot resonator
摘要： A stable narrow-linewidth dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber laser is demonstrated using a microfiber knot resonator (MKR). A MKR made by the microfiber knotting method exhibits the characteristics of flexibility, high quality factor and broad free spectral range and can be used as a comb-like ultra-narrow band pass filter. SLM operation of the fiber laser can be generated as a function of the Vernier effect by cascading a 650 μm diameter MKR in the ring cavity. In combination with a common fiber Bragg grating, narrow linewidths (0.016 nm and 0.019 nm) of dual wavelength are generated. Finally, a SLM ring laser with narrow linewidth and low-frequency noise is achieved. Simultaneous generation of first- and second-order optical vortex beams in the dual-wavelength fiber laser using different mode-selective couplers is demonstrated.
关键词： fiber lasers,fiber optics,optical communication
更新于2025-11-28 14:24:03
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High-Resolution Temperature Sensor Based on Single-Frequency Ring Fiber Laser via Optical Heterodyne Spectroscopy Technology
摘要： We demonstrate a high-resolution temperature sensor based on optical heterodyne spectroscopy technology by virtue of the narrow linewidth characteristic of a single-frequency fiber laser. When the single-frequency ring fiber laser has a Lorentzian-linewidth <1 kHz and the temperature sensor operates in the range of 3?85 ?C, an average sensitivity of 14.74 pm/?C is obtained by an optical spectrum analyzer. Furthermore, a resolution as high as ~5 × 10?3 ?C is demonstrated through optical heterodyne spectroscopy technology by an electrical spectrum analyzer in the range of 18.26–18.71 ?C with the figure of merit up to 3.1 × 105 in the experiment.
关键词： fiber optics sensors,high resolution,heterodyne spectroscopy,single-frequency laser
更新于2025-11-28 14:24:03
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Temperature fiber sensor based on single longitudinal mode fiber laser in 2?μm band with Sagnac interferometer
摘要： A single longitudinal mode (SLM) ?ber laser with a ring cavity based on Sagnac interferometer (SI) for temperature sensing in the 2-μm band is proposed and demonstrated. The simulation and experimental results show that the transmission spectrum of the SI ?lter is sensitive to temperature change. Based on this distinguishing feature, the correlation between the laser wavelength drift and temperature variation can be established. Experimental results show that the proposed laser operates stably at the resonant wavelength of 1988.21 nm and the optical signal-to-noise ratio is approximately 55 dB at ambient temperature. Through continuous measurement for 100 min, the ?uctuation of the output laser power is lower than 0.74 dB, and the resonant wavelength shift is less than the minimum resolution of the spectrometer of 0.05 nm. This indicates that it has good stability for a certain period of time. At the same time, the laser operates stably in SLM state. A temperature sensitivity of 2.09 nm/°C is obtained in experiment. Notably, the proposed ?ber laser sensor possesses the merits including high sensitivity, low cost and simple structure, which are bene?cial to its practical application.
关键词： Fiber optics sensors,Temperature measurement,Sagnac interferometer,Fiber laser,2-μm band
更新于2025-11-28 14:23:57
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Long tapered fiber with array of FBG
摘要： A tapered optical fiber with an adiabatic transition from single-mode to a few-mode part has been fabricated with an array of fiber Bragg gratings being inscribed during the drawing process. We demonstrate that the propagating optical signal remains single-mode along the tapered fiber FBG array even in a multimode part of it. The spectral width of the reflected signal from the tapered optical fiber is 4 nm. The level of the reflected signal is up to 5% at some wavelengths.
关键词： Tapered optical fibers,Fiber optics sensors,Fiber Bragg gratings
更新于2025-11-28 14:23:57
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Arc-Induced Long Period Gratings in Erbium-Doped Fiber
摘要： In this paper, we report about the fabrication of long period gratings (LPGs) directly into an Erbium-doped fiber, by using the electric arc discharge technique. The attention is focused on the writing process and the resulting properties, by considering gratings with different periods and measuring their spectra over a wide wavelength range. The LPGs show high order attenuation bands with tunable resonance wavelengths and depths up to 30 dB, while the lengths of the final devices are in range 20–45 mm. The polarization-dependent loss of these LPGs is also measured, for the first time in this kind of fiber. As further novelty, the influence of surrounding refractive index, applied strain, and temperature is investigated and discussed in comparative manner. Based on the achieved results, this fabrication procedure can be adapted to a specific application, for example in optical communications, signal processing, and sensing fields.
关键词： waveguide devices,Fiber gratings,fiber optics systems,sensors
更新于2025-11-28 14:23:57
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Tailoring Properties of Microcavity In-line Mach-Zehnder Interferometer by the Microcavity Enlargement using Femtosecond Laser
摘要： This work presents a theoretical analysis and experimental verification of fine-tuning of the spectral response and refractive index (RI) sensitivity of microcavity in-line Mach-Zehnder interferometer (μIMZI). The μIMZIs were fabricated using femtosecond (fs) laser micromachining in standard single-mode fibers as circular cavities with a diameter of 60 μm. Next, the structures underwent fs laser post-processing, which included fabrication of an additional cavity with the same diameter but shifted by 15 μm or 30 μm against the center of the initial microcavity. Different depths of the additional structures were investigated. The enlargement of the microcavity allows for tailoring the spectral response, i.e., it shifts the interference pattern by more than 200 nm, with no introduction of any additional losses and distortions in the spectrum. As the additional effect, regardless of the size of the extension, the sensitivity of the enlarged μIMZI was improved by 32%.
关键词： Fiber optics sensors,Laser materials processing,Interferometry,Microcavities,Microstructure fabrication
更新于2025-11-28 14:23:57
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In-fiber Mach-Zehnder Interferometer Exploiting a Micro-cavity For Strain and Temperature Simultaneous Measurement
摘要： An in-fiber Mach-Zehnder interferometer (MZI) with a micro-cavity (MC) exploited for strain and temperature simultaneous measurement. The research is carried out experimentally and simulatively. The MC fabricated by splicing a hollow quartz tube between two single mode fibers serves as a light splitter for the two arms of MZI beams and a Fabry–Pérot interferometer (FPI) component at the same time. Thus both functions of a Mach-Zehnder interferometer and a Fabry–Pérot interferometer were implemented in a single sensor. With aid of the different response of the MZI and FPI to the strain and temperature, this device can achieve a simultaneous measurement and the strain/temperature cross-sensitivity issue has been alleviated. Such a composite interference structure, possess with the characteristics of easy making, high performance-price ratio provides a promising approach to implement strain and high-temperature simultaneous measurement.
关键词： Fabry–Pérot interferometer,Fiber Optics Sensors,Mach-Zehnder interferometer
更新于2025-11-28 14:23:57
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Performance of Bandwidth Extension Techniques for High-Speed Short-Range IM/DD Links
摘要： In recent years, advanced modulation formats for short-range high-speed communications have been increasingly discussed to achieve the transmission rates needed to satisfy the future demand of broadband services. A key parameter in such applications is the use of low-cost optical components, which mainly means the use of intensity modulation (IM) and direct detection (DD) schemes. In order to exploit the available bandwidth offered by the latest optical components, high-speed data converters (DAC and ADC) are required. However, the available bandwidth of DACs and ADCs is generally smaller, than that of their optical counterparts, resulting in a capacity bottleneck. This issue can be addressed by bandwidth extension techniques, which enable the full use of the optical components. In this paper, two high-speed systems are presented and experimentally analyzed for an optical link based on IM/DD, utilizing a bandwidth extension technique based on electrical up/down-conversion and passive signal combining. The experiment for the first system uses two independent sub-signals, with a total bandwidth beyond 40 GHz and enables transmission rates up to 180 Gb/s. Different aspects of the system are highlighted including general performance, transmission distance, use of different modulation formats and the influence of important components. For the second system, the experiment consists of the generation of a spectrally continuous pulse amplitude modulation (PAM) signal with the help of two sub-signals and its transmission over an optical IM/DD link. The challenges and requirements for hardware and software are discussed and the impact of power and phase mismatches between both sub-signals are investigated as well.
关键词： Fiber optics and optical communications,Fiber optics links and subsystems
更新于2025-09-23 15:23:52
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[IEEE 2018 OCEANS - MTS/IEEE Kobe Techno-Ocean (OTO) - Kobe, Japan (2018.5.28-2018.5.31)] 2018 OCEANS - MTS/IEEE Kobe Techno-Oceans (OTO) - A High Dynamic Range in Situ Flow Sensor
摘要： High dynamic range and high accuracy flow sensor is a highly desirable device in quantifying mixing in the atmosphere and the ocean, which is critical in our understanding of energy dissipation and flux studies. We discuss a design that utilizes only a single point sensor in different angles, based on our novel oriented temperature Fabry-Perot using interferometry approach. We report the sensitivity of a high-dynamic range sensor head orientation in such configuration. We discuss initial configuration, data collection, processing, analysis and calibration including sensor orientation for future deployment.
关键词： Fabry-Perot interferometer,flow meter,turbulence,kinetic energy dissipation,fiber optics
更新于2025-09-23 15:23:52