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- 2019
- higher- order modes
- few-mode regime
- on-board cable systems
- mode coupling
- laser-based multi-Gigabit data transmission
- large core multimode optical fiber
- industrial networks
- differential mode delay
- Optoelectronic Information Science and Engineering
- Povolzhskiy State University of Telecommunications and Informatics (PSUTI)
- Malaviya National Institute of Technology Jaipur
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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) - Spatial Kerr Beam Self-Cleaning in Yb-Doped Multimode Fiber Taper
摘要： Spatial Kerr beam self-cleaning (KBSC), which transforms an output speckled beam in a quasi-single mode beam in graded index (GRIN) multimode optical fibers (MMFs), has been reported recently [1,2]. GRIN MMFs are also interesting waveguides for supercontinuum (SC) generation in the visible and near infrared regions, as successfully demonstrated by launching femtosecond or subnanosecond pulses in the anomalous (1550 nm) or normal (1064 nm) dispersion regime, respectively [1,3]. The spectral broadening features were explained through the interplay between spatiotemporal multimode soliton oscillations and dispersive wave generation in fibers with parabolic index profile. On the other hand, tapered optical fibers are well known to provide a number of useful features, including strong mode confinement capability, small scale diameter and broad SC generation [4,5]. Herein, we report visible-short infrared SC generation in combination with KBSC in long (~10 m) tapered Yb-doped MMFs, with parabolic index profile and parabolic doping concentration.
关键词： supercontinuum generation,Spatial Kerr beam self-cleaning,graded index multimode optical fibers,Yb-doped multimode fiber taper
更新于2025-09-12 10:27:22
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A Resonant Gas Sensor Based on Multimode Excitation of a Buckled Microbeam
摘要： We report a new gas sensing technique based on the simultaneous tracking of multiple modes of vibration of an electrothermally heated bridge resonator operated near the buckling point. The proposed technique maximizes the sensitivity of the sensor to changes in gases concentrations. We demonstrate a 200% frequency shift in contrast to 0.5% resistance change using the conventional resistive technique. The method also demonstrates selective identification for some gases without the need for surface functionalization of the microstructure. The proposed method is simple in principle and design and is promising for achieving practical low-cost gas sensors.
关键词： buckling point,multimode,Gas sensor,heated microbeam
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) - Broadband Mid-Infrared Directional and Multimode Interference Couplers in GLS Glass Fabricated using Femtosecond Laser Direct-Writing
摘要： The first broadband directional and multimode interference couplers for the mid-infrared centred around 4 μm wavelength are demonstrated. The devices are inscribed into commercial chalcogenide glass (Gallium-Lanthanum-Sulfide, GLS) provided by the University of Southampton using a tightly focused 800 nm, 5.1 MHz repetition rate femtosecond laser. Low loss waveguides are formed by placing 3 individual laser written tracks next to each other, resulting in propagation losses as low as 0.22 dB/cm. These waveguides are used to create asymmetric directional couplers, where the propagation constant in one arm is tailored to flatten the chromatic response of the device. By locally changing the feedrate at which the sample is translated through the focus, a change in propagation constant is obtained in the coupling region of the device. This yields a 3 dB coupler with a wavelength flattened response over a 500 nm wavelength band for ±5% variation in the coupling ratio compared to < 200 nm for a symmetric directional coupler. Multimode interference couplers were created by placing 26 laser inscribed tracks next to each other to form a 140 μm wide multimode interference region with lengths ranging from 5 to 10 mm. Asymmetry inside the multimode interference regions induced by the sequential writing process results in port dependent cross coupling ratios. Yet, close to 3 dB coupling was found for an 8.1 mm long device when injecting into the left input. The device features nearly perfect achromaticity across 3.75 to 4.25 μm.
关键词： GLS glass,mid-infrared,multimode interference couplers,femtosecond laser direct-writing,directional couplers
更新于2025-09-12 10:27:22
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The Critical Adiabatic Linear Tapered Waveguide Combined with a Multimode Waveguide Coupler on an SOI Chip
摘要： A multimode waveguide interference (MMI) coupler is combined with a critical linear tapered waveguide on a silicon-on-insulator (SOI) chip. When the TE0 mode is a critical adiabatic mode conversion from a single-mode waveguide to an extreme linear tapered waveguide combined with an MMI, this linear tapered waveguide is achieved to the maximum divergence angle (i.e., the shortest length). The maximum divergence angle is expressed by θ ≤ 2 tan? 1[(0.35Wmmi ? Ws)/(0.172Lmmi)] under a 1 × 1 MMI combined with this critical linear tapered waveguide. The expression formula is demonstrated by three di?erent widths of a 1 × 1 MMI of 4 μm/8 μm/12 μm combined with the critical linear tapered waveguide. So, the maximum divergence angle is obtained at θ ? 16°/14°/8°, with respect to this linear tapered waveguide loss of 0.022 dB/0.172 dB/0.158 dB, and this linear tapper length is reduced by 93.7%/92.9%/87.5% than the divergence angle θ ? 1°. The output power of a 1 × 1 MMI combined with a critical linear tapered waveguide is enhanced at least 1.5 times under 0.95 above condition.
关键词： multimode waveguide interference (MMI) coupler,TE0 mode,linear tapered waveguide,silicon-on-insulator (SOI) chip,adiabatic mode conversion
更新于2025-09-12 10:27:22
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Nonlinear Fiber Optics || Multimode fibers
摘要： Multimode fibers were first used for nonlinear optics during the 1970s because most optical fibers available at that time supported multiple modes. The situation changed in the 1980s when single-mode fibers were commercialized in view of their telecommunication applications. The interest in multimode fibers re-surfaced after 2005, partly motivated by their use for space-division multiplexing in optical communication systems. As a byproduct of this interest, the nonlinear effects in multimode fibers have been studied extensively since 2010. This chapter covers recent advances in a systematic fashion. Three types of multimode fibers are introduced in Section 14.1, where we also discuss modes supported by them. Section 14.2 extends theory of Section 2.3 to obtain a set of coupled nonlinear equations for various fiber modes. These equations are used in Sections 14.3 to discuss modulation instability and soliton formation in multimode fibers. The focus of Section 14.4 is on the intermodal nonlinear effects that transfer energy among the modes. The spatio-temporal effects are discussed in Section 14.5 with emphasis on spatial beam cleanup and supercontinuum generation through multimode fibers. Section 14.6 is devoted to the nonlinear phenomena in multicore fibers.
关键词： modulation instability,spatio-temporal effects,spatial beam cleanup,soliton formation,multimode fibers,multicore fibers,supercontinuum generation,nonlinear optics,space-division multiplexing,intermodal nonlinear effects
更新于2025-09-12 10:27:22
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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) - Development of 850 nm and 910 nm Vertical-Cavity Surface-Emitting Lasers for 50-100 Gb/s Applications
摘要： New generation of datacom standards require vertical cavity surface emitting lasers (VCSELs) operating at data rates beyond 50 Gbaud in on-off-keying (NRZ) and pulse amplitude modulation (PAM4) formats. New applications in Ethernet also demand extended wavelength range of the devices to enable wavelength division multiplexing (WDM) in multimode fiber. We report on 850 nm and 910 nm single mode industrial technology VCSELs capable for error free NRZ data transmission at 60 Gb/s over 800 m and 400 m of OM5 multimode fiber (MMF), respectively. Both types of VCSELs are also suitable for PAM4 transmission up to 60 Gbaud.
关键词： data transmission,multimode fiber,vertical cavity surface–emitting laser,oxide aperture,wavelength division multiplexing
更新于2025-09-12 10:27:22
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Random mode coupling assists Kerr beam self-cleaning in a graded-index multimode optical fiber
摘要： In this paper, we numerically investigate the process of beam self-cleaning in a graded-index multimode optical ?ber, by using the coupled-mode model. We introduce various models of random linear coupling between spatial modes, including coupling between all modes, or only between degenerate ones, and investigate the e?ects of random mode coupling on the beam self-cleaning process. The results of numerical investigations are in complete agreement with our experimental data.
关键词： Nonlinear optics,Kerr e?ect,Multimode ?bers,Beam self-cleaning
更新于2025-09-12 10:27:22
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Lossy Mode Resonance Generation on Sputtered Aluminum-Doped Zinc Oxide Thin Films Deposited on Multimode Optical Fiber Structures for Sensing Applications in the 1.55 μm Wavelength Range
摘要： In this work, we demonstrated lossy mode resonance (LMR) generation in optical fiber structures based on multimode fibers coated with aluminum-doped zinc oxide (AZO) films. AZO thin films were deposited by using radio frequency magnetron sputtering. In order to exhibit the usefulness of the LMR effect for sensing applications in optical fiber based systems, the deposition conditions of the AZO film coatings were set to obtain the second LMR order within the 1.55 μm wavelength range. An optical transmission configuration setup was used to investigate the LMR effect on fiber structures based on the use of no-core and cladding-removed multimode fibers coated with AZO films synthesized from metallic sputtering targets with different proportions of Zn:Al, 92:8% and 98:2%, at atomic concentrations. The optical and electrical/chemical features of the AZO films were characterized with UV–vis and XPS spectroscopy, respectively. The optical response of the proposed sensing configuration to refractive index (RI) variations was experimentally demonstrated. For the best approach, the sensitivity of wavelength displacement to RI variations on the liquid surrounding media was found to be 1214.7 nm/RIU.
关键词： multimode fiber,lossy mode resonance,optical fiber sensors,reactive RF magnetron sputtering,aluminum-doped zinc oxide
更新于2025-09-12 10:27:22
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Applications of Silicon Photonics in Sensors and Waveguides || New Approach to Mach-Zehnder Interferometer (MZI) Cell Based on Silicon Waveguides for Nanophotonic Circuits
摘要： In this chapter, we present a new scheme for Mach-Zehnder Interferometer (MZI) structure based on only one 4×4 multimode interference (MMI) coupler. We design the new MZI cell on the silicon on insulator (SOI) platform. The MZI based on directional coupler and 2×2 MMI coupler is also investigated in detail. The new MZI cell is a basic building block for photonic applications such as optical quantum gate, optical computing and reconfigurable processors. The numerical simulations show that our approach has advantages of compact size, ease of fabrication with the current complementary metal oxide semiconductor (CMOS) circuitry.
关键词： multimode interference,finite difference time difference,directional coupler,modified effective index method,multimode waveguide,finite difference method,silicon on insulator
更新于2025-09-11 14:15:04
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[IEEE 2019 Systems of Signals Generating and Processing in the Field of on Board Communications - Moscow, Russia (2019.3.20-2019.3.21)] 2019 Systems of Signals Generating and Processing in the Field of on Board Communications - Simulation-Based Prediction of 100-μm-Core Multimode Optical Fiber Bandwidth for 10GBase-LX Systems
摘要： This work is concerned with application of earlier on developed an alternative method for simulation of piecewise regular multimode fiber optic links operating in a few-mode regime for computation of laser-excited optical pulse dynamics during its propagation over irregular silica graded- index multimode optical fibers (MMFs) with extremely large core diameter. Proposed model is based on the piecewise regular representation, and it takes into account launching conditions, differential mode delay, both lower- and higher- order mode chromatic dispersion, differential mode attenuation, mode mixing and power diffusion occurring due to real fiber irregularity and micro- and macro-bends. We present some results of simulation 10GBase-LX optical signal transmission over 100-μm-core MMFs graded-index refractive index profile corresponding to the typical laser-optimized MMFs 50/125 of ISO/IEC Cat. OM2+/OM3 scaled up to 100 μm core.
关键词： higher- order modes,few-mode regime,on-board cable systems,mode coupling,laser-based multi-Gigabit data transmission,large core multimode optical fiber,industrial networks,differential mode delay
更新于2025-09-11 14:15:04