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Switchable, tunable and highly stable multi-wavelength fiber laser based on a spectral filter
摘要： In this work, a switchable and tunable multi-wavelength erbium-doped fiber laser based on a spectral filter is presented. Here, the filter is formed by polymer and silicon layers at the tip of an optical fiber. The laser emission wavelengths are mainly determined by the position where the most intense fringes of the reflectivity spectrum of the filter occurs. Moreover, the number of laser emissions are controlled and switched by using a variable optical attenuator inserted into the laser cavity. In this way, single-, dual-, triple-, and quadruple-laser emissions can be obtained within the long operating span from ~1526–~1565 nm. Additionally, the multi-wavelength laser emissions had a side mode suppression ratio ?36.48 dBm, a minimum wavelength spacing of ~3.6 nm, and the best peak power difference was 0.45 dB. Besides, the wavelength shift and peak power fluctuation were ?0.095 nm and ?3.14 dB, respectively, over half an hour. Finally, the emissions of the multi-wavelength laser can be tuned within a tunable range of 2.93 nm by taking advantage of some thermal properties of the Si and polymer layers.
关键词： multi-wavelength fiber laser,tunable,switchable
更新于2025-11-28 14:24:03
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Fiber-Optic Magnetic Field Sensing Based on Microfiber Knot Resonator with Magnetic Fluid Cladding
摘要： A kind of all-fiber magnetic field sensing structure is proposed and demonstrated here. The sensing element includes a microfiber knot resonator (MKR) cladded with magnetic fluid (MF). The low-index MgF2 slab is adopted as the substrate. The sensitivity increases with the decrease of the MKR ring diameter. The achieved maximum magnetic field sensitivity is 277 pm/mT. The results of this work have the potential to promote the development of magnetically controllable optical devices and the design of ultra-compact cost-effective magnetic field sensors.
关键词： quality factor,finesse,magnetic fluid,microfiber knot resonator
更新于2025-11-28 14:24:03
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Multi-parameter sensor based on single Long Period Grating in Panda fiber for the simultaneous measurement of SRI, temperature and strain
摘要： In this work, a three-parameter sensor for the simultaneous measurement of surrounding refractive index (SRI), temperature and strain is presented. It is based on a single Long Period Grating (LPG) written in a polarization-maintaining Panda fiber, by means of a simple technique based on Electric Arc Discharge. For the purpose, it is performed the monitoring of the wavelength shift of three different resonances, each one associated to a different cladding mode. Moreover, the set of resonances is acquired for two polarizations of the input light, i.e. aligned to the slow and fast axis of the fiber. The three-parameter sensing is promoted by the fact that the resonance dips show different sensitivities to SRI, temperature and strain, which change their magnitudes and signs when the polarization is switched. It was demonstrated that the sensor can be applied to simultaneously measure SRI in range 1.33–1.40, temperatures comprised in 20–60 °C, and strain of hundreds of με. This device could find application in the fields of materials science and structural health monitoring.
关键词： Refractive index sensor,Temperature sensor,Fiber grating sensor,Strain sensor,Multi-parametric sensor,Long period grating
更新于2025-11-28 14:24:03
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A fast interrogation system of FBG sensors based on low loss jammed-array wideband sawtooth filter
摘要： In this paper, a low loss jammed-array wideband sawtooth (JAWS) filter is built based on a finite reflection virtually imaged array (FRVIA) which has a lower reflectivity of the exit surface compared to a virtually imaged phased array (VIPA). This filter can be used as an edge filter to interrogate the fiber Bragg grating (FBG) sensors. A fast FBG sensing system is set up to detect the strain wave of iron pipe to demonstrate the use of this interrogator. The result shows that the JAWS based interrogation system has advantages of high speed, low loss and high sensitivity.
关键词： JAWS filter,Fiber Bragg grating (FBG) interrogator,Finite reflection virtually imaged array
更新于2025-11-28 14:24:03
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Mode-locked near-infrared thulium doped fibre laser using evanescent field effect with Bi <sub/>2</sub> O <sub/>3</sub> saturable absorber
摘要： Using the evanescent field effect, a high power passively mode-locked laser with a pulse duration of 1.85 ps and the pulse energy of 13.15 pJ is demonstrated. A Bi2O3 solution is used as a saturable absorber (SA) on a side polished fibre incorporated into a thulium doped fibre laser cavity for operation in the mid-infrared range. The 37.61% SA has a modulation depth and creates a highly stable mode-locked pulse output with a short pulse duration. The calculated net cavity dispersion at central wavelength is ?1.4 ps2, indicating operation is in the anomalous dispersion regime and confirmed by the presence of Kelly’s side-bands observed in the generated optical spectrum. Radio frequency analysis reveals a high signal to noise ratio, making this laser stable for use in telecommunication systems.
关键词： thulium doped fibre laser,evanescent field effect,Bi2O3 saturable absorber
更新于2025-11-28 14:23:57
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L-band tunable and dual-wavelength mode locked fiber laser with NCF-GIMF based SA
摘要： A hybrid structure of no-core fiber and graded-index multimode fiber (NCF-GIMF) is demonstrated, which can be used as both the saturable absorber (SA) and the wavelength selective element. By employing such a device, an L-band wavelength tunable Er-doped mode-locked laser is realized and stable single solitons of ~1.7ps, with continuously tunable wavelengths from 1574 nm to 1601.1 nm, are generated. Moreover, dual-wavelength mode-locked laser operation at 1575.4 nm and 1603 nm is achieved, with pulse duration of 1.2 ps and 1.7 ps, respectively. The proposed device is simple and compact, and represents an effective approach for tunable and dual-wavelength mode-locked fiber laser operation.
关键词： Laser tuning,Optical fiber devices,Laser mode locking,Fiber-graded index multimode fiber,Fiber nonlinear optics
更新于2025-11-28 14:23:57
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Nanotube mode-locked, wavelength and pulsewidth tunable thulium fiber laser
摘要： Mode-locked oscillators with highly tunable output characteristics are desirable for a range of applications. Here, with a custom-made tunable filter, we demonstrate a carbon nanotube (CNT) mode-locked thulium fiber laser with widely tunable wavelength, spectral bandwidth, and pulse duration. The demonstrated laser’s wavelength tuning range reached 300 nm (from 1733 nm to 2033 nm), which is the widest-ever that was reported for rare-earth ion doped fiber oscillators in the near-infrared. At each wavelength, the pulse duration can be regulated by changing the filter’s bandwidth. For example, at ~1902 nm, the pulse duration can be adjusted from 0.9 ps to 6.4 ps (the corresponding output spectral bandwidth from 4.3 nm to 0.6 nm). Furthermore, we experimentally and numerically study the spectral evolution of the mode-locked laser in presence of a tunable filter, a topic that has not been thoroughly investigated for thulium-doped fiber lasers. The detailed dynamical change of the mode-locked spectra is presented and we observed gradual suppression of the Kelly sidebands as the filter’s bandwidth is reduced. Further, using the polarization-maintaiing (PM) cavity ensures that the laser is stable and the output laser’s polarization extinction ratio is measured to exceed 20 dB.
关键词： thulium fiber laser,spectral bandwidth,polarization-maintaiing cavity,Kelly sidebands,tunable wavelength,pulse duration,Mode-locked oscillators,carbon nanotube
更新于2025-11-28 14:23:57
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Self-wavelength-sweeping in a bi-directional thulium-doped fiber ring laser
摘要： We report for the first time the self-wavelength-sweeping phenomenon of a bi-directional thulium-doped fiber ring laser. The laser wavelength can spontaneously sweep in both lasing directions at a rate up to 0.2 nm s?1 over 15 nm sweeping range in the 1.95 μm wavelength region. The sweeping rate can be controlled by simply changing the state of polarization of the laser cavity. The laser can be tuned to generate a periodical wavelength-swept output with microsecond pulses in the time domain. The sweep rate can also be tuned to zero to give a static lasing wavelength.
关键词： self-wavelength-sweeping,thulium-doped fiber ring laser,polarization control,bi-directional
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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Passively Q-switched fiber laser utilizing new hafnium–bismuth–erbium co-doped fiber as saturable absorber
摘要： A stable all-fiber passively Q-switched erbium-doped fiber laser emitting at 1559 nm is proposed and demonstrated using an 8-cm-long hafnium–bismuth–erbium co-doped fiber (HBEDF) as a saturable absorber (SA). The HBEDF is fabricated in-house and has a linear absorption of around 5.2 dB at the laser operating wavelength of 1559 nm. The Q-switching pulses are obtained with an input pump power ranging from 50 to 121 mW. It has the pulse repetition rate of 81.57 kHz, the shortest pulse width of 3.31 ls, output power of 10 mW, pulse energy of 123 nJ and peak power of 37.3 mW at the maximum pump power of 121 mW. The corresponding signal-to-noise ratio of the electrical spectrum is measured to be around 70 dB, which indicates the stability of the laser. To the best of our knowledge, this is the first demonstration of the deployment of HBEDF SA in generating a robust and steady pulsed laser in 1.5-micron region.
关键词： Fiber saturable absorber,Q-switcher,Fiber laser
更新于2025-11-28 14:23:57