- 标题
- 摘要
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- 实验方案
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How to unravel the chemical structure and component localization of individual drug-loaded polymeric nanoparticles by using tapping AFM-IR
摘要： AFM-IR is a photothermal technique that combines AFM and infrared (IR) spectroscopy to unambiguously identify the chemical composition of a sample with tens of nanometer spatial resolution. So far, it has been successfully used in contact mode in a variety of applications. However, the contact mode is unsuitable for soft or loosely adhesive samples such as polymeric nanoparticles (NPs) of less than 200 nm of wide interest for biomedical applications. We describe here the theoretical basis of the innovative tapping AFM-IR mode that can address novel challenges in imaging and chemical mapping. The new method enables gaining information not only on NP morphology and composition, but also reveals drug location and core–shell structures. Whereas up to now the locations of NP components could only be hypothesized, tapping AFM-IR allows accurately visualizing both the location of the NPs’ shells and that of the incorporated drug, pipemidic acid. The preferential accumulation of the drug in the NPs’ top layers was proved, despite its low concentration (<1 wt%). These studies pave the way towards the use of tapping AFM-IR as a powerful tool to control the quality of NP formulations based on individual NP detection and component quantification.
关键词： tapping mode,chemical mapping,core–shell structure,drug localization,polymeric nanoparticles,AFM-IR
更新于2025-11-14 15:18:02
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Broadband generation of the first-order OAM modes in two-mode fiber by offset splicing and fiber rotating technology
摘要： We demonstrate a simple, compact, and cost-effective all-fiber structure to generate the first-order orbital angular momentum (OAM) modes over a broad wavelength range. The offset splicing between a polarization-maintaining single mode fiber (PM-SMF) and a two-mode fiber (TMF) is adopted to excite LP11 mode in the TMF from LP01 mode in SMF. Then the OAM ± 1,1 modes are generated by rotating a customized fiber rotator, which can modulate the phase difference of the two degenerate LP11 modes (OAM ± 1,1 = LP11a ± i × LP11b). The interference phenomenon formed between OAM and Gaussian beams, which displays a fork-shape or spiral interference pattern, is used to confirm the generation of OAM modes. It should be noted that a PM fiber coupler and PM-SMFs are utilized in the experiment, which can avoid coupling of modes with orthogonal polarizations and then improves the OAM mode stability. Besides, the complexity of the OAM generation system is also reduced because the devices like polarization controller and half-wave plate are omitted by employing PM fibers. Based on this simple offset splicing and fiber rotating technology, the broadband generation of OAM ± 1,1 modes are experimentally demonstrated in wavelength range of 1530–1566 nm.
关键词： Fiber rotating,Polarization-maintaining single mode fiber,Two mode fiber,Offset-splicing,Orbital angular momentum mode
更新于2025-09-23 15:23:52
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Experimental and analytical investigation of LP01-LP11 mode interference
摘要： We introduce an analytical theory of LP01-LP11 mode interference and investigate its application in curvature measurement. Under the weakly guiding condition, an analytical formulation for predicting dip wavelength in the transmission spectrum is proposed. The applicability of the proposed formulation is further explored in terms of curvature measurement based on a few-mode multi-core fiber (FM-MCF). The mechanism of curvature response is analytically presented and verified through numerical simulation and experiments. The comparison of analytical and numerical results is found to be in good agreement when curvature varies from 0 to 1.8 m?1. Meanwhile, a good agreement between the experimental and theoretical values of dip wavelength shift is also observed. Moreover, we find that the temperature effect can be eliminated by using two cores of the FM-MCF during curvature measurement. Through experimental tests, the curvature values are accurately predicted under varying temperatures with maximum error controlled within 6.6%.
关键词： LP01-LP11 mode,Few-mode multi-core fiber (FM-MCF),Mode interference,Temperature,Curvatures sensor
更新于2025-09-23 15:23:52
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Comparative analysis of capacity oriented Integrated AMI modulation technique for the deployment of radio over fiber system
摘要： To improve the spectral efficiency and to reduce non-linear distortion in the optical system, various advanced modulation techniques have been investigated for radio over fiber (RoF) system. The investigation indicates the high data rate distortion less transmission for long-haul RoF system still further investigation is required to improve spectral efficiency and to get the reduction in signal degradation. In this paper, an advanced modulation technique referred as integrated alternate mark inversion modulation technique based upon external modulation (electro-absorption modulator) has been designed and simulated. The results show better performance in terms of performance metrics i.e. Q-factor (25.15) and BER (4e-140) and also enhance the data transmission capabilities up to 100 Gbps covering the long distance of 250 km resulting a reasonable reduction in signal degradation particularly chromatic dispersion effects for long-haul transmissions.
关键词： Single mode fiber—SMF,Carrier suppressed return to zero—CSRZ,Erbium doped fiber amplifier—EDFA,RoF,Dispersion compensating fiber—DCF,Multi-mode fiber—MMF
更新于2025-09-23 15:23:52
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[IEEE 2018 17th International Conference on Ground Penetrating Radar (GPR) - Rapperswil, Switzerland (2018.6.18-2018.6.21)] 2018 17th International Conference on Ground Penetrating Radar (GPR) - Noise suppression of GPR data using Variational Mode Decomposition
摘要： Ground penetrating radar (GPR) has been used in the many aspects, such as civil engineering and the earth sciences. And the analysis and noise suppression of GPR data have always been the research focus. In this study, a new self-adaptive time-frequency decomposition tool called the variational mode decomposition (VMD) is introduced. We use the VMD method to derive a set of stationary sub-components, and based on the decomposition, we separate the valid signals and the components which are corresponded to the noise. One trace of GPR data are given to test the effect of the VMD decomposition, and the empirical mode decomposition (EMD) is also employed as a comparison. And a primary noise-suppression method based on the VMD scheme is also proposed. The application of the field GPR data further demonstrates the better performance of the proposed method in both noise suppression and the retention of geophysical events.
关键词： ground penetrating radar (GPR),mode decomposition,variational mode decomposition (VMD),noise reduction or suppression
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - Chengdu, China (2018.5.7-2018.5.11)] 2018 International Conference on Microwave and Millimeter Wave Technology (ICMMT) - A High Efficiency TE<inf>01</inf>- TE<inf>11</inf> Mode Converter
摘要： A high efficiency TE01-TE11 mode converter is designed and analyzed based on coupled wave theory. The optimal configurations of a three-period converter is obtained to realize the optimal conversion at 30.5 GHz. The simulation results show that a conversion efficiency of up to 99.85% is got with a bandwidth of 4.4% over a converting efficiency of 95%, and the TE11 mode purity is also up to 99.9% at the output port.
关键词： high mode purity,TE01-TE11,mode converter,high conversion efficiency
更新于2025-09-23 15:23:52
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Performance evaluation of mode group power coupling for short reach SDM
摘要： The profound understanding of mode coupling in spatial multiplexed optical systems is required for performance optimization purposes. In this contribution different optical coupler technologies are compared with respect to their bit-error rate (BER) performance as multiplex devices in a (2 × 2) multiple-input multiple-output (MIMO) environment. Therefore, the power coupling coefficients between mode groups for all testbed components are determined at 1327 nm with a method based on impulse response measurements. This method and its refinements are presented in this work. By taking the obtained power coupling coefficients, the MIMO impulse responses are simulated and the corresponding BER performance for different launch parameters is studied. The simulation setup includes single-mode fiber (SMF) to multi-mode fiber (MMF) splices aligned with different radial eccentricities for mode group specific excitation, different multi-mode couplers for mode multiplexing, a 1 km OM4 grade MMF and a multi-mode fusion coupler for demultiplexing. Here, the setup with the customized fusion coupler shows the best BER results in comparison to other coupler technologies. In addition, the optimal choice of the SMF to MMF launch eccentricity highly depends on the implemented coupler technology. Particularly, deviations of 2 μm from the optimal launch setup can lead to a tenfold increase in the BER. It is noteworthy, that the optimal setup does not always include the center launch condition.
关键词： Multi-Mode MIMO,Mode Group Power Coupling,Coupler Technology
更新于2025-09-23 15:23:52
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Total Ionizing Dose Effects of 55-nm Silicon-Oxide-Nitride-Oxide-Silicon Charge Trapping Memory in Pulse and DC Modes
摘要： The 60Co-γ ray total ionizing dose radiation responses of 55-nm silicon-oxide-nitride-oxide-silicon (SONOS) memory cells in pulse mode (programmed/erased with pulse voltage) and dc mode (programmed/erased with direct voltage sweeping) are investigated. The threshold voltage and off-state current of memory cells before and after radiation are measured. The experimental results show that the memory cells in pulse mode have a better radiation-hard capability. The normalized memory window still remains at 60% for cells in dc mode and 76% for cells in pulse mode after 300 krad(Si) radiation. The charge loss process physical mechanisms of programmed SONOS devices during radiation are analyzed.
关键词： dc mode,pulse mode,total ionizing dose,radiation effects,SONOS memory
更新于2025-09-23 15:23:52
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[IEEE 2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) - Amsterdam (2018.8.27-2018.8.30)] 2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) - Investigation on Degradation of Common Mode Noise Suppression with Electrostatic Discharge Protection Array
摘要： In this paper, it is proposed that the electrostatic discharge protection devices may degrade the common-mode noise suppression. The mode conversion of ESD protection devices for single and multiple differential transmission lines are investigated. Experiments are set up to measure the scattering parameters and common-mode current of common-mode filter cascading different ESD protection devices. From the experimental results, the cases with four-line ESD protection array perform worse mode conversion and common-mode noise suppression.
关键词： mode conversion,common-mode noise suppression,high-speed input/output interface,electrostatic discharge
更新于2025-09-23 15:23:52
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Polarization-Independent, Narrowband, Near-IR Spectral Filters via Guided Mode Resonances in Ultrathin a-Si Nanopillar Arrays
摘要： We report the optical properties obtained through experiments, simulation, and theory, of ultra-thin (<0.1λ), amorphous Si nanopillar arrays embedded in a thin film of SiO2 designed for narrowband filtering for multi- and hyper-spectral imaging in the near-infrared. The fabricated nanopillar arrays are square-packed with subwavelength periodicity, heights of ~100 nm, and a radius-to-spacing ratio, r/a, of ~0.2. Specular reflection measurements at normal incidence demonstrate that these arrays behave as narrow stopband filters in the near-infrared (λ = 1300-1700 nm) and attain ~90% reflectivity in band and a full width at half maximum as low as 20 nm. Using a combination of full wave simulations and theory, we demonstrate that these narrowband filtering properties arise from efficient grating coupling of light into guided modes of the array because the nanopillar arrays serve as photonic crystal slabs. This phenomenon is known as a guided mode resonance. We discover that the spectral location of these resonances is passively tunable by modifying array geometry and is most sensitive to nanopillar spacing. Theoretical photonic crystal slab band diagrams accurately predict the spectral locations of the observed resonance and provide physical insights into and support the guided mode resonance formulation. This work demonstrates that these ultra-thin all-dielectric nanopillar arrays have advantages over existing hyperspectral filter designs because they are polarization independent and do not suffer from material absorption loss and have significant implications for minimizing imaging device size.
关键词： guided mode resonance,nanopillar array,hyperspectral
更新于2025-09-23 15:23:52