- 标题
- 摘要
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- 实验方案
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All polarization-maintaining passively mode-locked Yb-doped fiber laser: pulse compression using an anomalous polarization-maintaining photonic crystal fiber
摘要： We report the generation of short pulses at 1 μm using an all-polarization-maintaining (PM) fiber configuration. The pulses are provided by an all normal-dispersion Fabry-Perot Yb-doped cavity and are compressed with an anomalous polarization-maintaining photonic crystal fiber (PM PCF). Opposed to standard configurations; here the filtering action is solely performed by the finite bandwidth of the gain medium. The laser generates 8 ps width sech2 profile pulses at 1046.8 nm with a -10 dB bandwidth of 5.9 nm. After compression using the PM PCF, pulses with an FWHM of 3 ps were obtained, limited by the actual value of the available anomalous dispersion. We also report the changes in the output light pulses when both the net-normal dispersion of the cavity and the medium gain length were varied. We found that the lack of a specific filter within the cavity does not deteriorate the performance as compared with previous works.
关键词： dissipative solitons,photonic crystal fibers,fiber laser,polarization maintaining
更新于2025-09-16 10:30:52
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Opto-Mechanical Interactions in Multi-Core Optical Fibers and their Applications
摘要： Optical fibers containing multiple cores are being developed towards capacity enhancement in space-division multiplexed optical communication networks. In many cases, the fibers are designed for negligible direct coupling of optical power among the cores. The cores remain, however, embedded in a single, mechanically-unified cladding. Elastic (or acoustic) modes supported by the fiber cladding geometry are in overlap with multiple cores. Acoustic waves may be stimulated by light in any core through electrostriction. Once excited, the acoustic waves may induce photo-elastic perturbations to optical waves in other cores as well. Such opto-mechanical coupling gives rise to inter-core cross-phase modulation effects, even when direct optical crosstalk is very weak. The cross-phase modulation spectrum reaches hundreds of megahertz frequencies. It may consist of discrete and narrow peaks, or may become quasi-continuous, depending on the geometric layout. The magnitude of the effect at the resonance frequencies is comparable with that of intra-core cross-phase modulation due to Kerr nonlinearity. Two potential applications are demonstrated: single-frequency opto-electronic oscillators that do not require radio-frequency electrical filters, and point-sensing of liquids outside the cladding of multi-core fibers, where light cannot reach.
关键词： opto-electronic oscillators,multi-core fibers,stimulated Brillouin scattering,optical fiber sensors,Opto-mechanics,nonlinear fiber-optics
更新于2025-09-16 10:30:52
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Buckled Conductive Polymer Ribbons in Elastomer Channels as Stretchable Fiber Conductor
摘要： Conductors that can sustain large strains without change in resistance are highly needed for wearable electronic systems. Here, the fabrication of highly stretchable coaxial fiber conductors through self-buckling of conductive polymer ribbons inside thermoplastic elastomer channels, using a “solution stretching–drying–buckling” process, is reported. The unique hierarchically buckled and conductive core in the axial direction makes the resistance of the fiber very stable, with less than 4% change when applying as much as 680% strain. These fibers can then be directly used as stretchable electrical interconnects or wearable heaters.
关键词： resistance change,conductive polymers,buckling,stretchable fiber conductors,coaxial fibers
更新于2025-09-16 10:30:52
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Intense red emission on dilute Mn-doped CaYAlO4-based ceramics obtained by laser floating zone
摘要： The laser floating zone (LFZ) technique was used to produce polycrystalline fibers composed by P21/c monoclinic Y4Al2O9 (YAM) and P?421m tetragonal CaYAl3O7 (CYAM) phases embedded into I4/mmm tetragonal CaYAlO4 matrix. The scanning electron microscopy and X-ray diffraction patterns put in evidence the strong effect of growth rate on the microstructural and phases’ evolution. Besides the microstructural and structural analysis, complementary optical techniques as photoluminescence (PL), PL excitation (PLE), and lifetime measurements were used to characterize the produced fibers. The nonintentionally doped fibers were shown to exhibit an intense deep red emission likely due to Mn4+ trace impurities. From the PLE measurements, average crystal field strength was estimated with Dq/B ~ 2.94. Temperature-dependent PL measurements revealed that the red luminescence is due to the overlap of transitions from the almost electronic degenerate 2E and 4T2 excited states to the 4A2 ground state. The emission from the two excited states arises due to the breakdown of the adiabatic approximation. The overall luminescence intensity of the red emission was found to decrease from 11 K to RT, and the internal quantum efficiency, estimated from the ratio of the integrated luminescence at high and low temperatures, was found to be 60%. Time-resolved spectroscopy indicates a single decay time of ca. 2.0 ms at room temperature, corresponding to the spin and parity forbidden 2E → 4A2 transition.
关键词： Laser floating zone,Crystal field strength,Polycrystalline fibers,Mn4+ trace impurities,Red emission
更新于2025-09-16 10:30:52
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Propagation Mode Retention Using Strongly Coupled Multi-Core Fiber
摘要： Strongly coupled MCF is studied in propagation mode retaining capability as regular multi-mode fiber has an issue of mode crosstalk. As a result, mode retention characteristics of 5dB at 80 mm bending radius has been confirmed successfully.
关键词： Fibers for space division multiplexing,Strongly coupled fiber,Mode crosstalk
更新于2025-09-16 10:30:52
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[IEEE 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Fukuoka, Japan (2019.7.7-2019.7.11)] 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) - Multi-core Fiber Fabrication in Over-Cladding Bundled Rods Method Applying Polygonal Rods
摘要： The implementation of multi-core fiber fabrication using the over-cladding bundled rods method results in large core deformation. We have achieved core deformation of approximately 1%, on average, through a method applying hexagonal rods.
关键词： Fiber design and fabrication,Fibers for space division multiplexing
更新于2025-09-16 10:30:52
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Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy
摘要： Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO2) and is doped with Gd3+ ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2–62.9 MeV protons and 2–6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce3+ and Cu+. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd3+-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce3+ and Cu+ fibers with a Birks’ constant, kB, of (0.0162 ± 0.0003) cm/MeV in comparison to (0.0333 ± 0.0006) cm/MeV and (0.0352 ± 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting kB for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.
关键词： Bragg peak,dosimetry,Gd3+-doped silica,optical fibers,quenching,sol-gel technique,proton therapy
更新于2025-09-16 10:30:52
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Distributed Fiberoptic Sensor for Simultaneous Humidity and Temperature Monitoring Based on Polyimide-Coated Optical Fibers
摘要： Along temperature, humidity is one of the principal environmental factors that plays an important role in various application areas. Presented work investigates possibility of distributed fiberoptic humidity monitoring based on humidity-induced strain measurement in polyimide (PI)-coated optical fibers. Characterization of relative humidity (RH) and temperature response of four different commercial PI- and one acrylate-coated fiber was performed using optical backscattering reflectometry (OBR). The study addresses issues of temperature-humidity cross-sensitivity, fiber response stability, repeatability, and the influence of annealing. Acrylate-coated fiber exhibited rather unfavorable nonlinear RH response with strong temperature dependence, which makes it unsuitable for humidity sensing applications. On the other hand, humidity response of PI-coated fibers showed good linearity with fiber sensitivity slightly decreasing at rising temperatures. In the tested range, temperature sensitivity of the fibers remained humidity independent. Thermal annealing was shown to considerably improve and stabilize fiber RH response. Based on performed analysis, a 20 m sensor using the optimal PI-coated fibers was proposed and constructed. The sensor uses dual sensing fiber configuration for mutual decoupling and simultaneous measurement of temperature and RH variations. Using OBR, distributed dual temperature-RH monitoring with cm spatial resolution was demonstrated for the first time.
关键词： fiberoptic sensors,distributed humidity sensing,polyimide-coated optical fibers,optical frequency-domain reflectometry,dual sensing
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Tailorable Supercontinuumc Generation in Liquid-Composite-Core Fibers
摘要： Nonlinear light generation in optical fibers is an indispensable tool for generating light to access wavelengths away of the fundamental laser lines broadening the field of applications in biophotonics, metrology, and communications. However, most multi-wavelength sources rely on glass fibers which are static in their material properties after fabrication, thus post-tuning their properties is impossible. Complementary to the pressure-adjustable gas-filled hollow-core fibers in the high power laser regime, liquid-core fibers (LCF) offer a versatile platform for tunable nonlinear light generation and pulse control in the low- to medium-power regime. Recently, we demonstrated accurate control of the soliton fission process via temperature due to the large thermo-optical coefficient of the core liquid. However, those experiments were performed with rather cost-intensive thulium laser technology. Here, we present the composition of the liquid core as further degree of control to switch the operation regime of a simple step-index LCF from normal to anomalous dispersion, thus, opening the soliton regime for the inexpensive and technology-rich telecom SCL bands. We show the design and applicability limits (e.g., guidance and absorption limits) of multiple liquid-composite-core fibers with focus on broadband supercontinuum generation. Fig. 1b exemplarily shows the zero-dispersion at pump wavelength (ZDPW) and two isolines of the V-parameter over varying core diameter and amount of the admixture C2Cl4 in CCl4, clearly revealing a favorable parameter domain for soliton fission close to the zero-dispersion (colored in green). We confirm the design maps experimentally by investigating the nonlinear spectral broadening of a 30 fs pump pulse at 1.56 μm center wavelength launched into multiple LCFs with varying core composition and diameter (see Fig. 1a). The LCFs are fabricated by capillary force-assisted filling of capillaries safely mounted in sealed opto-fluidic mounts. The core diameter of each sample is chosen such that the V-parameter is well above the empirically found limit of V = 1.6 (see Fig. 1b). Output spectra are measured for increasing input power. The measured output spectra in Fig. 1e show clean soliton fission exemplarily for a LCF infiltrated with 20 vol% C2Cl4 in CCl4, indicated by efficient generation of non-solitonic radiation at around 1.3 μm and a soliton red-shifting towards 1.7 μm. This is in distinct contrast to the unaltered output spectrum of a normal dispersive CCl4-core fiber in Fig. 1c. Nonlinear pulse propagation simulations match the experiments well (see Fig. 1d,f). Similar experiments have been conducted using deuterated toluene and nitrobenzene as admixture to CCl4 significantly increasing the bandwidth of the output spectrum. In conclusion, we unambiguously show dispersion tuning of LCFs to a great extent by small changes in the core composition directly offering unexplored ways of online tailorable nonlinear light generation and control in the telecom regime.
关键词： liquid-composite-core fibers,soliton fission,nonlinear light generation,supercontinuum generation,telecom SCL bands
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Continuum Generation in Higher-Order Modes of Photonic Crystal Fibers
摘要： Low-noise supercontinuum (SC) generation in photonic crystal ?bers (PCFs) can be achieved by using pump pulses of femtosecond (fs) duration and low soliton numbers [1]. The small cores sizes needed to obtain anomalous dispersion for pump wavelengths in the Yb gain band (typically 1030-1070 nm) implies a severe restriction on power for such pump pulses. One possible strategy for power scaling is to pump in higher-order ?ber modes, which can attain the desired dispersion properties in larger cores. This contribution aims to explore the properties of such continua, in particular the conditions necessary to retain a single-mode character of the output.
关键词： nonlinear mode coupling,photonic crystal fibers,higher-order modes,supercontinuum generation
更新于2025-09-16 10:30:52