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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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Femtosecond Soliton Erbium-doped Fiber Laser with a Symmetrical GIMF-SIMF-GIMF Saturable Absorber
摘要： A femtosecond soliton erbium-doped fiber ring laser with the symmetrical saturable absorber (SA) of graded index multimode fiber-step index multimode fiber-graded index multimode fiber (GIMF-SIMF-GIMF) is proposed and proved. Based on the nonlinear multimode interference (NL-MMI) effect of SA, the fiber laser achieved femtosecond soliton mode-locking operation and repetition rate tuning. The duration of soliton was 364 fs at 1562.5 nm and repetition rate was tunable from 10.29 MHz to 763.36 MHz. In the structure of SA, a short step index multimode fiber (SIMF) was inserted between two graded index multimode fibers (GIMFs) to generate more high-order modes，adjust the self-focusing length, and improve operation stability of mode-locked fiber laser. The SA also has the advantages of immunity to the external environment variation, high damage threshold and inoxidizability, which make the laser operate stably for a long time.
关键词： Femtosecond soliton,ultrafast fiber lasers.,mode-locked fiber lasers,nonlinear multimode interference
更新于2025-09-11 14:15:04
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Ultra-Sharp Multimode Waveguide Bends with Subwavelength Gratings
摘要： Mode-division multiplexing (MDM) is attractive to enhance the link capacity of optical interconnects by using multiple mode-channels in multimode bus waveguides. As sharp waveguide bends are very important for realizing dense photonic integrated circuits, here ultra-sharp multimode waveguide bends for MDM systems are proposed and demonstrated by using subwavelength grating waveguide structures on silicon. An ultra-sharp S-bend with a radius of 10 μm is realized for the ?rst time to enable a low-loss and low-crosstalk MDM optical interconnect with three mode-channels. For this proposed ultra-sharp subwavelength grating multimode waveguide bend (SMWB) with a 90° bending angle, the theoretical excess losses for the TE0, TE1, and TE2 modes are 0.1–0.3 dB, 0.18–0.22 dB, and 0.3–0.5 dB, respectively, in a wavelength band of 1500–1600 nm. Meanwhile, inter-mode crosstalks are very low (less than ?30 dB) for all mode-channels. For the fabricated 90°-SMWB, the excess losses for the TE0, TE1, and TE2 modes are 0.1–0.3 dB, 0.2–0.4 dB, and 0.3–0.7 dB while the inter-mode crosstalk is approximately ?22 dB in a wavelength band of 1520–1600 nm. The proposed SMWB is also extended for more than three mode-channels.
关键词： bend,multimode,waveguide,silicon
更新于2025-09-11 14:15:04
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An Alcohol-Soluble Polymer Electron Transport Layer Based on Perylene Diimide Derivatives for Polymer Solar Cells
摘要： Modular multilevel converter with integrated battery energy storage system (MMC-BESS) has been proposed for energy storage requirements in high-voltage applications with large-scale renewable energy resources. The MMC-BESS is essentially a three-port converter which can transfer energy between any two of the ac port, dc port, and BESS, constituting multimode operation of the system. Different from conventional MMCs, the state-of-charge (SOC) inconsistency among batteries would magnify the submodule capacitor voltage unbalance issue in the MMC-BESS. In this study, an improved capacitor voltage balancing method applicable for multimode operation of MMC-BESS is proposed by adjusting ac and dc modulation indexes simultaneously. After that, the ratio of ac and dc modulation indexes is optimised to enhance the tolerance of unbalanced power among SMs within phase arm, greatly improving the SOC equalisation rate. Based on the proposed capacitor voltage balancing method, the control structure is given and the dynamic model is conducted for the analytic design of the closed-loop controller. Finally, the simulations and experimental results validate the effectiveness and feasibility of the proposed control strategy.
关键词： SOC equalisation,Multimode operation,Modular multilevel converter,Battery energy storage system,Capacitor voltage balancing
更新于2025-09-11 14:15:04
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Laser-Induced Deposition of Carbon Nanotubes in Fiber Optic Tips of MMI Devices
摘要： The integration of carbon nanotubes (CNTs) into optical fibers allows the application of their unique properties in robust and versatile devices. Here, we present a laser-induced technique to obtain the deposition of CNTs onto the fiber optics tips of multimode interference (MMI) devices. An MMI device is constructed by splicing a section of no-core fiber (NCF) to a single-mode fiber (SMF). The tip of the MMI device is immersed into a liquid solution of CNTs and laser light is launched into the MMI device. CNTs solutions using water and methanol as solvents were tested. In addition, the use of a polymer dispersant polyvinylpyrrolidone (PVP) in the CNTs solutions was also studied. We found that the laser-induced deposition of CNTs performed in water-based solutions generates non-uniform deposits. On the other hand, the laser-induced deposition performed with methanol solutions generates uniform deposits over the fiber tip when no PVP is used and deposition at the center of the fiber when PVP is present in the CNTs solution. The results show the crucial role of the solvent on the spatial features of the laser-induced deposition process. Finally, we register and study the reflection spectra of the as-fabricated CNTs deposited MMI devices.
关键词： multimode interference,carbon nanotubes,laser-induced deposition,optical fibers
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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Four-Wave Mixing of a Laser and Its Frequency-Doubled Version in a Multimode Optical Fiber
摘要： It is shown that it is possible to couple a laser beam and its frequency-doubled daughter into a multimode optical ?ber through the four-wave mixing nonlinear process and generate a new wavelength. The frequency-doubled daughter can be generated in an external crystal with a large second order nonlinearity. It is argued that while this possibility is within the design parameter range of conventional multimode optical ?bers, it necessitates a lower-bound for the core-cladding refractive index contrast of the multimode optical ?ber.
关键词： Kerr optical ?ber,third harmonic generation,frequency-doubling,Four-wave mixing,new wavelength generation,multimode nonlinearity
更新于2025-09-11 14:15:04
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - On-Wafer CPW Standards for S-Parameter Measurements of Balanced Circuits Up to 40 GHz
摘要： The Multimode Thru-Reflect-Line (TRL) calibration technique is applied to perform mixed-mode scattering parameter measurements of on-wafer differential circuits. The paper describes the design and the realization of coupled coplanar waveguide (CCPW) standards on quartz (SiO2) substrate in the Ground-Signal-Ground-Signal-Ground (GSGSG) configuration. Simulation and measurement results for a mismatched transmission line demonstrate the validity of the method up to 40 GHz.
关键词： Coplanar waveguide,Multimode TRL calibration,vector network analyzer,mixed-mode Scattering parameters,differential circuits,microwave measurements
更新于2025-09-10 09:29:36
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Multi-mode photocatalytic performances of CdS QDs modified CdIn2S4/CdWO4 nanocomposites with high electron transfer ability
摘要： In general, quantum dots have the property of generating a plurality of charge carriers using hot electrons or using a single high-energy photon to improve the photocatalytic properties of the material. In this paper, CdS QDs@CdIn2S4/CdWO4 modified by CdS QDs was synthesized by the microwave-assisted hydrothermal method, and its composition, crystal structure, morphology, and surface physicochemical properties were well characterized. Electron microscopy results showed that CdS QDs@CdIn2S4/CdWO4 composite material exhibited a sheet structure with a length of ca. 350 nm and a width of ca. 50 nm, and CdS QDs uniformly distributes with a diameter of about 5 nm on the sheet structure. UV-visible diffuse reflectance tests showed that the combination of CdS QDs and CdIn2S4 can extend the light absorption range of CdWO4 to the visible region. Photoluminescence spectroscopy confirmed that CdS QDs had efficient electron transport capabilities. The multi-mode photocatalytic activity of CdS QDs@CdIn2S4/CdWO4 showed an excellent ability to degrade organic pollutants. Under the conditions of no co-catalyst and Na2S-Na2SO3 as the sacrificial agent, the hydrogen production of CdS QDs@CdIn2S4/CdWO4 can reach 221.3 μmol g?1 when exposed to visible light (λ > 420 nm) for 8 h.
关键词： CdS QDs,Quantum dots,Microwave-assisted hydrothermal method,CdWO4,Multimode photocatalysis,H2 evolution,CdIn2S4
更新于2025-09-10 09:29:36
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Shape-optimized multi-mode interference for a wideband visible light coupler
摘要： We developed a wideband visible light coupler based on multi-mode interference (MMI) using silica planar lightwave circuit (PLC) technology. The MMI shape was designed by using analytical and numerical optimization techniques to expand the transmission range around the target wavelength. We used this method for green (G) and blue (B) coupler to expand G and B transmission range. The transmittances of the fabricated coupler designed by the hybrid design method were ?1.5 to ?1.0 dB at wavelengths of 430 to 465 nm and ?0.5 to ?0.1 dB at wavelengths of 508 to 625 nm, respectively. The coupler length is about 1 mm without an input/output circuit. The coupler can be used for the whole wavelength range of G and B as a GB coupler.
关键词： Displays,Multimode interference,Wavelength division multiplexing,RGB coupler,Optical waveguides
更新于2025-09-10 09:29:36
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Statistical description of transport in multimode fibers with mode-dependent loss
摘要： We analyze coherent wave transport in a new physical setting associated with multimode wave systems where reflection is completely suppressed and mode-dependent losses together with mode mixing are dictating the wave propagation. An additional physical constraint is the fact that in realistic circumstances the access to the scattering (or transmission) matrix is incomplete. We have addressed all these challenges by providing a statistical description of wave transport which fuses together a free probability theory approach with a filtered random matrix ensemble. Our theoretical predictions have been tested successfully against experimental data of light transport in multimode fibers.
关键词： statistics,multimode fiber,random matrix theory
更新于2025-09-09 09:28:46