- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Nonlinear Fiber Optics || Polarization effects
摘要： A major simplification was made in Section 2.3 while deriving the nonlinear Schr?dinger (NLS) equation. It consisted of assuming that the polarization state of the incident light is preserved during its propagating inside an optical fiber. This is not really the case in practice. In this chapter we focus on the polarization effects and consider the coupling between the two orthogonally polarized components of an optical field induced by the nonlinear phenomenon known as cross-phase modulation (XPM). The XPM is always accompanied with self-phase modulation (SPM) and can also occur between two optical fields of different wavelengths, a situation covered in Chapter 7.
关键词： optical fibers,nonlinear Schr?dinger equation,polarization effects,self-phase modulation,cross-phase modulation
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Stimulated Raman scattering
摘要： Stimulated Raman scattering (SRS) is an important nonlinear process that can turn optical fibers into broadband Raman amplifiers and tunable Raman lasers. It can also severely limit the performance of multichannel lightwave systems by transferring energy from one channel to the neighboring channels. This chapter is devoted to a thorough study of SRS phenomenon in optical fibers. Section 8.1 presents the basic theory behind SRS with emphasis on the pump power required to reach the Raman threshold. SRS under continuous-wave (CW) and quasi-CW conditions is considered in Section 8.2, where we also discuss the performance of fiber-based Raman lasers and amplifiers. Ultrafast SRS occurring for pulses of 100-ps width or less is considered in Sections 8.3 and 8.4 for normal and anomalous group-velocity dispersion (GVD), respectively. In both cases, attention is paid to the walk-off effects together with those resulting from self-phase modulation (SPM) and cross-phase modulation (XPM). Section 8.5 focuses on the polarization effects.
关键词： Raman amplifiers,optical fibers,Stimulated Raman scattering,nonlinear processes,group-velocity dispersion,Raman lasers,polarization effects,self-phase modulation,cross-phase modulation
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Stimulated Brillouin scattering
摘要： Stimulated Brillouin scattering (SBS) is a nonlinear process that can occur in optical fibers at input power levels much lower than those needed for stimulated Raman scattering (SRS). It manifests through the generation of a backward-propagating Stokes wave that carries most of the input power, once the Brillouin threshold is reached. For this reason, SBS limits the channel power in optical communication systems. At the same time, it can be useful for making fiber-based Brillouin lasers and amplifiers. This chapter is devoted to the SBS phenomenon in optical fibers. Section 9.1 presents the basic concepts behind SBS with emphasis on the spectrum of Brillouin gain. Section 9.2 focuses on the Brillouin threshold in the case of a continuous-wave (CW) pump and the techniques used to control it. Fiber-Brillouin amplifiers and their properties are discussed in Section 9.3. The dynamic aspects of SBS are the focus of Section 9.4, where we discuss SBS for a pulsed pump together with phenomena such as SBS-induced modulation instability and optical chaos. Section 9.5 is devoted to Brillouin lasers operating continuously or pulsed.
关键词： Brillouin amplifiers,Brillouin threshold,Brillouin lasers,optical fibers,nonlinear process,Stimulated Brillouin scattering
更新于2025-09-12 10:27:22
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Application of Raman and Brillouin Scattering Phenomena in Distributed Optical Fiber Sensing
摘要： We present a review of the basic operating principles and measurement schemes of standalone and hybrid distributed optical fiber sensors based on Raman and Brillouin scattering phenomena. Such sensors have been attracting a great deal of attention due to the wide industrial applications they offer, ranging from energy to oil and gas, transportation and structural health monitoring. In distributed sensors, the optical fiber itself acts as a sensing element providing unique measurement capabilities in terms of sensing distance, spatial resolution and number of sensing points. The most common configuration exploits optical time domain reflectometry, in which optical pulses are sent along the sensing fiber and the backscattered light is detected and processed to extract physical parameters affecting its intensity, frequency, phase, polarization or spectral content. Raman and Brillouin scattering effects allow the distributed measurement of temperature and strain over tens of kilometers with meter-scale spatial resolution. The measurement is immune to electromagnetic interference, suitable for harsh environments and highly attractive whenever large industrial plants and infrastructures have to be continuously monitored to prevent critical events such as leakages in pipelines, fire in tunnels as well as structural problems in large infrastructures like bridges and rail tracks. We discuss the basic sensing mechanisms based on Raman and Brillouin scattering effects used in distributed measurements, followed by configurations commonly used in optical fiber sensors. Hybrid configurations which combine Raman and Brillouin-based sensing for simultaneous strain and temperature measurements over the same fiber using shared resources will also be addressed. We will also discuss advanced techniques based on pulse coding used to overcome the tradeoff between sensing distance and spatial resolution affecting both types of sensors, thereby allowing measurements over tens of kilometers with meter-scale spatial resolution, and address recent advances in measurement schemes employing the two scattering phenomena.
关键词： distributed fiber optic sensing,Raman scattering,non-linear phenomena in optical fibers,Brillouin scattering,strain and temperature measurements
更新于2025-09-12 10:27:22
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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) - Fiber Fuse Effect in Hollow Core Optical Fibers
摘要： Fiber fuse effect (FFE) is one of phenomena restricting the high power/intensity/pulse energy laser radiation transport through optical fibers. FFE (alternatively, optical discharge (OD) propagation through fiber core) was initially observed in solid state silica fibers [1], and later in fibers of various materials and constructions, including microstructured fibers. Hollow core fibers developed in recent decades can transport high power laser radiation. However, it was recently discovered that FFE is present in such fibers as well [2]. In this work OD propagation through hollow-core revolver fibers (RFs) was investigated. Reflecting cladding of RFs consists of only one layer of capillaries [3]. The cross section pictures of two RFs used in experiments are shown in Fig.1(a,b: RF1 and RF2). All our RFs had transparency bands at laser radiation wavelength 1.06 m. The Q-switched mode-locked Nd:YAG solid state laser was used in our experiments to reach a high enough radiation intensity in the fiber core. The laser radiation consisted of nanosecond trains of picosecond pulses (PPs): the train duration was 130 ns, duration of PP was 100 ps at repetition rate 76 MHz. The average output power of the laser was 3 W. The laser radiation was launched into and passed the ~50 cm RF without any significant disturbances. However, touching of the output end of the fiber with a metal plate gave rise to OD propagation with an average velocity Vav of ~1m/s. In the case of RF1 the silica structure of the fiber was completely destroyed after the OD passage, and its fragments were held together only by the polymer cladding. In the case of RF2 having a twice as thick support tube the fiber can be inspected after OD passage as a whole. It turned out that Vav depends essentially on the fact whether RF was during the experiment covered by polymer or not. In the last case Vav was ~3 times higher (~3 m/s) than for coated fiber (Fig.1, e). Each PP left in the RF2 fingerprint in the form of capillary destruction region of ~100 m length, and these regions were separated from each other by ~100 m regions of undamaged capillaries (Fig.1,c). And in the case of uncoated RF2 (Fig.1,d) the fingerprints of PP trains are separated by ~1 mm from each other contributing to the Vav increase.
关键词： Fiber fuse effect,laser radiation,revolver fibers,optical discharge,hollow core optical fibers
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - A Materials Approach Toward the Mitigation of Nonlinearities in Glass Optical Fibers
摘要： Power scaling in high energy fiber-based laser systems is limited by optical nonlinearities. As opposed to the complex micro-structured large mode area (LMA) fibers typically developed to mitigate these parasitic nonlinear effects, the present work instead advocates another approach, a material approach, in which nonlinearities are mitigated through a judicious choice of dopants in the fiber core. To demonstrate the effectiveness of this approach, multicomponent core – silica glass cladding optical fibers are fabricated using the molten core method and the role played by the glass dopants in the mitigation of nonlinearities discussed. More specifically, highlights are made on multicomponent alkaline-earth (Sr, Ca) doped-silica fibers exhibiting concomitant reduction of > 6 dB in the Brillouin gain coefficient, 1 – 2 dB in the Raman gain coefficient, and 2 – 3 dB in the thermo-optic coefficient relative to conventional silica fibers.
关键词： Brillouin scattering,Raman scattering,optical nonlinearities,optical fibers,multicomponent silicates,glass
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Symposium on Measurements & Networking (M&N) - Catania, Italy (2019.7.8-2019.7.10)] 2019 IEEE International Symposium on Measurements & Networking (M&N) - Water monitoring in smart cities exploiting plastic optical fibers and molecularly imprinted polymers. The case of PFBS detection
摘要： The detection of perfluorobutanesulfonic acid (PFBS) in water is presented for the first time exploiting a low-cost optical chemical sensing strategy, based on plastic optical fibers and molecularly imprinted polymers (MIPs), able to detect pollutants in water. The sensor's response measured in this work for the detection of PFBS is similar to the one obtained with Perfluorooctanesulfonate and investigated. The detection limit of PFBS is considered of interest when compared to those obtained by using different expensive traditional approaches, e.g. high performance liquid chromatography-mass spectrometry (HPLC-MS). Moreover, the use of this sensing approach is a very attractive perspective for fast, in situ, and remote low-cost detection of pollutants in water for smart cities applications.
关键词： molecularly imprinted polymers,pollutants,PFAs,Surface plasmon resonance,plastic optical fibers,optical fiber sensors,water quality,PFBS,Chemical sensors
更新于2025-09-11 14:15:04
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Space division multiplexing in standard multi-mode optical fibers based on speckle pattern classification
摘要： In optical communications the transmission bandwidth of single mode optical fibers is almost fully exploited. To further increase the capacity of a telecommunication link, multiplexing techniques can be applied across 5 physical dimensions: amplitude, quadrature, polarization, frequency and space, with all but the latter being nearly exhausted. We experimentally demonstrate the feasibility of an original space division multiplexing technique based on the classification of speckle patterns measured at the fiber’s output. By coupling multiple optical signals into a standard multimode optical fiber, speckle patterns arise at the fiber’s end facet. This is due to quasi-random interference between the excited modes of propagation. We show how these patterns depend on the parameters of the optical signal beams and the fiber length. Classification of the speckle patterns allows the detection of the independent signals: we can detect the state (i.e. on or off) of different beams that are multiplexed in the fiber. Our results show that the proposed space division multiplexing on standard multimode fibers is robust to mode-mixing and polarization scrambling effects.
关键词： space division multiplexing,mode-mixing,speckle patterns,polarization scrambling,optical communications,multimode optical fibers
更新于2025-09-11 14:15:04
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Hearing the Sounds of Aquatic Life Using Optical Fiber Micro-tip based Hydrophone
摘要： For marine bioacoustics applications, the sounds by aquatic animals must be recorded with high precision and minimal noise in order to extract valuable information. For such marine applications, we propose and demonstrate an optical fiber micro-tip based hydrophone. The hydrophone design consists of an extrinsic Fabry-Perot interferometer which utilizes fiber micro-tip and processed aluminium foil as two partially reflecting mirrors. The packaged optical fiber hydrophone of dimensions 1.4 cm x 1.4 cm x 2 cm, with a microtip diameter of 31.23 μm and natural rubber diaphragm of 6 mm diameter shows a high sensitivity of 8.94 nm/mPa or -41.42 dB re 1 nm/μPa at 1 KHz. The hydrophone shows an excellent signal to noise ratio and the noise-limited minimum detectable pressure is as low as 0.388 μPa/√Hz at 1 KHz. The linear working range of the hydrophone is 0-3950 Hz. The experimental results show that the proposed optical fiber hydrophone can very accurately detect the click trains produced by dolphins for echolocation. Further, depending on the applications, the performance parameters of the proposed hydrophone can be tailored by changing the diaphragm thickness and diameter, thus opening a new platform to study marine environment.
关键词： Optical fibers,Acoustic signal detection,Underwater Optical equipment,Underwater acoustics,fiber sensors
更新于2025-09-11 14:15:04
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Self‐Assembled Polyamidoamine Dendrimer on Poly (methyl meth‐ acrylate) for Plasmonic Fiber Optic Sensors
摘要： We report a novel one-step polyamidoamine (PAMAM) dendrimer based polymethyl methacrylate (PMMA) surface functionalization strategy for the development of polymeric optical (POF) based plasmonic sensors utilizing gold nanoparticles (AuNP). Simple contact angle measurements over PMMA sheets reveal the ability of the dendrimers to strongly bind to PMMA surface without additional acid/alkali pretreatment, unlike the conventional hexamethylene diamine (HMDA) based surface modification. Subsequently, U-bent POF probes with high evanescent wave absorbance sensitivity were exploited for relative quantification of the surface amine groups using fluorescein isothiocyanate (FITC) binding and efficient chemisorption of gold nanoparticles (AuNP) in order to identify the optimum conditions viz. dendrimer concentration, incubation time and dendrimer generation. While FITC binding showed a proportional increase in amine functional density with PAMAM concentration and time, interestingly the AuNP (40 nm) binding studies revealed the formation of loose PAMAM multilayers and their desorption. PAMAM (G4) concentration as low as 5 mM and incubation time of 24 h provide faster binding rate with densely packed AuNP and the RI sensitivity of ~ 15 (A546 nm/RIU). This simpler and inexpensive strategy could also be exploited for the development of functional PMMA substrates for various applications including nanotechnology, bio-imaging, drug delivery and analytical separations.
关键词： gold nanoparticles (AuNP),dendrimers,plasmonic sensors,polymethyl methacrylate (PMMA),polymeric optical fibers (POF),evanescent wave absorbance
更新于2025-09-11 14:15:04