Modulation Devices Research Articles

Nonlinear Optical Properties of the Topological Material Bi2Se3 Family for the Application of an Ultrafast Pulse Laser Based on the Occupied and Unoccupied Band Structures.

The Bi2Se3 family can exhibit many intriguing topological insulator properties, including a narrow bandgap and strong surface states, which show excellent nonlinear optical properties. Thinning bulk Bi2Se3 family materials to create a low-cost photoelectric modulation device and explaining the mechanisms of nonlinear optical differences in different types of materials remain challenges. Based on liquid-phase exfoliation technology and tapered fiber, this work prepared optoelectronic modulation devices for various samples within the Bi2Se3 family, quantitatively compared their nonlinear optical properties, and analyzed the sources of differentiation using the occupied and unoccupied multiband structure theory. The results correspond well to the phenomena observed in the ultrafast laser, which will provide strong support for the design of higher performance photoelectric devices based on topological insulators.

Innovative active terahertz modulator based on dynamic graphene-silicon arrays

This paper presents an innovative active terahertz (THz) modulator that utilizes dynamic graphene-silicon arrays (DGSAs) to overcome the challenges of dynamically manipulating THz waves. The DGSA combines the exceptional electrical properties of graphene with the enhanced optical absorption capabilities of silicon arrays, enabling dual-mode active control through optical pumping and electrical biasing. An 808 nm laser is used to photoexcite carriers in the silicon arrays for optical pumping while a bias voltage modulates the Fermi level of graphene, subsequently varying Si conductivity and influencing the transmission properties of THz waves. Simulations have demonstrated modulation depths of up to 94% at 2.5 THz in the transmission mode and 89% at 1 THz in the reflection mode. Furthermore, this study delves into a theoretical analysis and numerical simulations, exploring the modulation mechanisms, including the role of graphene’s Drude model and PN junction effects. These insights provide a robust theoretical framework for understanding the DGSA’s operation and lay a solid foundation for the design and optimization of high-performance THz modulation devices.

Nonlinear optical research on 2D NbSe2 nanosheets and their ultrafast photonics applications

Two-dimensional (2D) NbSe2 is a new material with a variety of excellent properties. In this article, 2D NbSe2 nanosheets are prepared using liquid phase exfoliation (LPE) and spin coating methods. At the same time, the properties of NbSe2 were calculated by using density functional theory (DFT), exploring the changes in the electronic band structure of NbSe2 with the number of layers, and studying the optical properties of NbSe2. The nonlinear optical properties caused by the Pauli blocking effect and the absorption spectra are studied through typical nonlinear testing techniques and an ultraviolet–visible-near-infrared (UV–VIS-IR) spectrophotometer. In addition, 2 µm solid-state pulse lasers have important applications in a variety of fields. For the first time, 2D NbSe2 nanosheets are prepared as saturable absorbers (SA) and applied them to solid-state lasers as nonlinear optical modulation devices, successfully achieving the generation of ultra-short pulse lasers with a pulse duration of 445.4 ps in 2 µm band. Our research results prove that 2D NbSe2 nanosheets is a promising nanomaterial, can be prepared into nonlinear optical modulation devices with excellent performance, and show great application potential as ultrafast photonic devices. It is beneficial to the miniaturization of solid-state pulse lasers in subsequent applications.

Multibarrier Collaborative Modulation Devices with Ultra-High Logic Operation Density.

The demands for highly miniaturized and multifunctional electronics are rapidly increasing. As scaling-down processes of transistors are restricted by physical limits, reconfigurable electronics with switchable operation functions for different tasks are developed for higher function integration based on split- or vertical-dual-gate structures. To promote the present reconfigurable electronics and exceed the function integration limit, the critical issue is to integrate complex operations into simple circuit forms by establishing more control dimensions. This work proposes a multibarrier collaborative (MBC) modulation architecture to increase the control dimension by multiple forms of potential barriers and achieves combinational and reconfigurable logic operations by a single MBC device. The MBC architecture exhibits ultrahigh logic operation density, including 58.8% area reduction for multiplexer operations and 71.4% area reduction for 4-logic reconfigurable operations. Besides, a hardware security module composed of 4 MBC devices implementing 8 types of logic operations is demonstrated. This work reveals an effective design of function integration for next-generation electronics.

Direct formation of pure copper layer on aluminum nitride by multibeam laser deposition with blue diode lasers

A demand of power module devices has been increasing for highly energy efficient social system. The insulated heat sink printed circuit board is the key component of power module devices, which is composed of copper and aluminum nitride (AlN) due to high thermal conductivity. The conventional method of the joining between copper and AlN is active metal brazing method, but there is an issue that the high heat treatment of this method generates thermal residual stress on the board and decrease the reliability. For that reason, the development of a direct bonding process between copper and AlN has been demanded. Therefore, we focused on the laser metal deposition (LMD) method, which is a selective heating and microfabrication process. The LMD method is a method in which a powder material is supplied to the processing point and irradiated with a laser to melt the powder and form layer on the surface of the substrate. Then, a blue diode laser with a wavelength of 450 nm, which has a high absorptivity of 60% for copper, is used as a heat source. In addition, the multibeam type LMD system has been installed for the uniform heating of powder. In this study, the laser power density, laser scanning speed, and powder feeding rate were changed to explore the conditions for forming a copper layer on the AlN substrate.

B-038 A Novel Ultrasensitive Single-Molecule Counting Technology for Quantitation of Low Abundance Biomarkers

Abstract Background There is a need for sensitive, robust, and scalable analytical methods for accurate, early detection of disease using less invasive sampling methods. Often, smaller volumes and low marker concentrations present challenges to achieving sufficient sensitivity and accuracy with traditional immunoassay methods. This is particularly the case for measuring markers for Alzheimer's and other neurological diseases in blood, where levels are typically at much lower concentrations than in CSF. Here we introduce a novel ultrasensitive technology for flow-based single molecule detection in an optofluidic chip. We have developed an Ultrasensitive Detection Module (UDM) device and optofluidic cartridge that enable easy integration of this technology into existing immunoassay systems. UDM sensitivity data is shown for three prototype biomarker assays in comparison to the Lumipulse G1200 (Fujirebio Inc., Japan). We also present analytical validation data for three Alzheimer’s Disease plasma biomarker assays developed on a fully automated benchtop analyzer with integrated UDM detector. Methods Ultrasensitive detection is achieved by integrated low-loss waveguide in an optofluidic chip that enables maximal excitation of fluorescent molecules traveling through a narrow fluidic channel. The resulting high-intensity emission is detected as a single digital event, enabling individual molecules to be counted without need for amplification. Fluorescence-based immunoassays were developed for detection with the UDM using high performance monoclonal antibodies and reagents (Fujirebio Inc., Japan). Capture antibodies were immobilized on magnetic particles and detection antibodies conjugated to a fluorescent reporter construct (“reporter-Ab”). Multiple incubation and wash steps were followed by dissociation of immune complexes and separation of reporter-Ab from magnetic particles. Released reporter-Ab molecules were injected into the UDM device for digital detection. Signal to noise performance was evaluated in the UDM using reporter construct alone (no assay), as well as for prototype PSA, IL-6, and TSH assays, to establish baseline performance for analytical sensitivity. Plasma assays for pTau181, Aβ1-40, and Aβ1-42 were developed and optimized for the automated benchtop analyzer and validated for analytical sensitivity (LOD/LOQ), linearity, parallelism, precision and repeatability using clinical samples. Results Detection signal-to-noise testing of the reporter construct alone (no immunoassay) demonstrated up to 1000-fold higher sensitivity than the Lumipulse G1200. Prototype assays for PSA, TSH, and IL-6 showed up to 118-fold, 36-fold, and 80-fold higher signal to noise ratio, respectively, when compared to the Lumipulse G1200. Plasma assays for pTau181, Aβ1-40, and Aβ1-42 showed preliminary LLOQs calculated at 0.03 pg/mL, 0.17 pg/mL and 0.37 pg/mL, respectively. Conclusions We have developed a new single molecule counting platform able to detect neurological biomarkers at sub-pg/ml levels in plasma, with the potential to provide sensitive and accurate diagnostic testing of low abundance biomarkers in blood. Such technologies can create new clinical value through higher detection sensitivity and accuracy in areas like Alzheimer’s and other neurological diseases, supporting clinical research and translation to clinical practice.

Graphene modulator and 2-bit encoder based on plasma induced transparency effect

Within this study, a periodic metasurface structure made up of two graphene strips, two fan-shaped graphene and a square ring graphene with notches is introduced to achieve plasma-induced transparency (PIT). The PIT effect is analyzed utilizing the Lorentz oscillatory coupling model, and it has been discovered that the theoretical values closely match the simulated values. The role of the Fermi level adjustments in graphene on the PIT effect was examined, and the PIT window was dynamically modified as the Fermi level changed, which was used to realize a 2-bit graphene encoder at 5.78 THz and 7.18 THz. The encoder boasts a greatest modulation depth of 80.9 % and exhibits a minimal insertion loss of 0.17 dB. By controlling the polarization direction of the incident photoelectric field, a high performance dual-channel switching modulator is successfully realized. Moreover, by increasing carrier mobility, the depth of modulation for the modulator at 11.22 THz is increased from 97.5 % to 99.5 %, and the insertion loss has dropped from 0.075 dB to 0.06 dB. In addition, the structure has superior sensing properties and slow light properties, featuring a sensitivity reaching up to 1.07 THz/RIU and a maximum group index of 293. The outcomes of our study contribute novel insights for the advancement of modulator, encoder, sensor technology and slow-light devices.

Design of a Simulation and Evaluation System for Athlete Technical and Tactical Training Based on Virtual Reality Technology

In order to avoid the influence of external environmental factors on athletes’ physical fitness and technical tactics, the author proposes the design and research of an integrated simulation training system for athletes’ physical fitness and technical tactics based on virtual reality. The hardware unit of the design system includes a 3D scanner module, VR glasses module, locator module, tracker module, and wireless transceiver device. The software module introduces virtual reality technology and designs a visual simulation module, trained object detection module, trained object tracking module, and overall control module. The simulation experiment results show that compared with existing systems, the training scene output clarity and frame rate of the designed system are better, and the thread switching time and signal mixing time are shorter, which fully proves that the designed system has higher operating efficiency and better application performance.

ID: 335853 Initial Clinical Safety and Feasibility from RESET-RA Study: Novel Neuroimmune Modulation Device for Rheumatoid Arthritis

ID: 335853 Initial Clinical Safety and Feasibility from RESET-RA Study: Novel Neuroimmune Modulation Device for Rheumatoid Arthritis

Multifaceted Analysis of L-Alanine-Doped Creatininium Benzene Sulphonate Single Crystals for Optical Modulation Application

Creatininium Benzene Sulphonate (CBS) and L-Alanine-doped Creatininium Benzene Sulphonate (ACBS) single crystals were grown using the slow evaporation technique. Xpert HighScore software was utilized to determine lattice parameters including Full Width at Half Maximum (FWHM), crystallite size, and lattice strain. Fourier transform infrared spectroscopy was used to identify the functional groups present in the samples. The thermal properties of CBS and ACBS crystals were analyzed using Thermogravimetric and Differential Thermal Analysis. Optical properties including optical conductivity, extinction coefficient, and refractive index were measured using UV-Vis spectroscopy. The mechanical characteristics of both samples were studied using Vicker’s microhardness testing, and the dielectric response was recorded for various frequencies. The second harmonic generation values of samples were compared to those of potassium dihydrogen phosphate. Overall, CBS and ACBS crystals demonstrate promising characteristics as sustainable materials for optical modulation. Incorporating amino acids, such as L-Alanine, enhances the photoconductive properties of the crystals by improving charge carrier mobility and reducing recombination rates, resulting in more efficient optical modulation. This study explores the impact of doping single crystals with amino acids on their optoelectronic and dielectric properties for potential applications in optical modulation devices. Specifically, this research investigates the role of L-Alanine, a zwitterionic amino acid, in enhancing the performance of CBS single crystals, with the aim of optimizing their structural, thermal, optical, and mechanical properties for optical modulation. These findings highlight the potential of amino acid-doped single crystals in advancing optical devices, driving innovations in optoelectronics and photonics.

Perovskite polycrystal for optically tuning terahertz interference fringes

We optically tuned the terahertz interference fringe using a perovskite polycrystal. Specifically, we used CH3NH3PbI3 polycrystals with different morphologies that were annealed at different temperatures. The largest modulations depth (23 %) was obtained for the CH3NH3PbI3 polycrystal drop-coated at 130 °C; this was also greater than that of a spin-coated CH3NH3PbI3 thin film. We demonstrated that the combination of a drop-coated CH3NH3PbI3 polycrystal with a metasurface allows modulation of terahertz waves. Using the interference formed by partial-through measurement and the shift of the periodic peak in the terahertz time-domain spectroscopy system, we experimentally verified that the perovskite polycrystal can redshift the terahertz-band interference fringes by 50 GHz by changing the optical power density of the external excitation light source. This provides a new idea and possibility for the development of novel terahertz modulation devices.

Four-frame pixel super-resolution method for lensless imaging systems

Lensless imaging systems have gained significant attention recently due to their advantages in terms of reduced size and weight compared to traditional lens-based systems. However, like other imaging methods, lensless imaging encounters challenges in resolving scenes with more details. In this article, we propose a novel four-frame super-resolution method specifically tailored for lensless imaging systems. Our approach shares similarities with previous lensless imaging systems, involving a sensor and a modulation device placed in front of the image sensor. We develop an explicit degradation downsampling model with sub-pixel shifts and provide the solution to corresponding inverse problem, may offering valuable guidance for other super-resolution imaging algorithms based on spatial displacements. By applying random lateral sub-pixel shifts, acquiring four low-resolution (LR) images, and fusing their spatial information, we achieve high-resolution (HR) sensor recordings, enabling super-resolution reconstruction of the imaging scene. Numerical simulations demonstrate approximately an improvement in spatial resolution compared to single-measurement methods. Furthermore, we evaluate the performance of our method across various lensless imaging systems utilizing different masks, validating its versatility and effectiveness in achieving higher resolution outcomes. Experimental results also support our proposed scheme's ability to achieve higher spatial resolution reconstruction in a real system.

Achieving a comparable transverse magneto-optical Kerr effect by spin–orbit field driven magnetoplasmonic

In this study, we propose and simulate a magnetoplasmonics heterostructure that utilizes spin–orbit fields to generate an internal magnetic field and create a significant magneto-optical effect. Our approach offers a new way to overcome the challenges of using permanent magnets or magnetic coils in conventional magnetoplasmonics, such as high-power consumption and non-scalability. We demonstrate that it is possible to create an appropriate amount of magnetic field using spin–orbit fields induced by the spin-Hall effect, such that the consumption power becomes reasonable and the dimensions could be miniaturized. This approach will be an important development in the field of magneto-optics, as it can lead to enhanced transverse magneto-optical Kerr effect in the present of surface plasmon polaritons. The proposed nanostructure consists of a ferromagnetic film adjacent to a heavy metal layer, both sandwiched between two noble metal films, and deposited on a dielectric prism. The strength of the Kerr signal strongly depends on the thickness of the ferromagnetic layer, with the maximum effect observed at a thickness of 5nm. This concept has potential for various nanophotonic and spintronic applications, particularly for developing high-speed active plasmonic devices for ultrafast light modulation.

Terahertz Modulation Properties Based on ReS2/Si Heterojunction Films

Low cost, low power consumption and high performance are urgent needs for the application of terahertz modulation devices in the 6G field. Rhenium disulfide (ReS2) is one of the ideal candidate materials due to its unique direct band gap, but it lacks in-depth research. In this work, a highly stable ReS2 nanodispersion was prepared by liquid-phase exfoliation, and a uniform, dense and well-crystallized ReS2 film was prepared on high-resistivity silicon by drop casting. The morphological, optical and structural properties of the ReS2/Si heterojunction film were characterized by OM, SEM, AFM, XRD, RS and PL. The terahertz performance was tested by using a homemade THz-TDS instrument, and the influence of different laser wavelengths and powers on the terahertz modulation performance of the sample was analyzed. The modulation depth of the sample was calculated based on the transmission curve, and the changes in the refractive index and conductivity of the sample with frequency at the corresponding laser power were calculated. The results show that the fabricated ReS2/Si heterojunction terahertz modulator can stably achieve 30% broadband modulation in the range of 0.3~1.5 THz under the low-power pumping of 1555 mW/cm2, and the maximum conductivity is 3.8 Ω−1m−1.

Design terahertz polarizers and vector polarized vortex terahertz wave generators based on the effective dielectric constant of metal gratings

Polarization and phase devices for terahertz waves have important applications in terahertz detection, imaging, communication, etc. Spatially variable metal gratings can be used for broad-spectrum, miniaturized, and low-cost terahertz polarization and phase modulation devices. Based on the effective dielectric constant and the theory of light propagation in multilayer media, we obtain the relationship between the transmittance and extinction ratio and the parameters such as the duty cycle of the metal grating, the frequency of the incident terahertz wave, the angle of incidence, the thickness of the metal grating, the refractive index of the substrate, and the thickness of the substrate. We propose a method of designing a spatially variable metal grating located on a transparent substrate. The designed spatially variable metal grating is also used to modulate the terahertz spatial polarization and phase to generate terahertz optical fields whose polarization and phase change simultaneously in space, such as azimuthally vector vortex terahertz optical fields, radially vector vortex terahertz optical fields, and so on. This will have important applications in terahertz time-domain spectroscopic detection, terahertz time-domain spectroscopic imaging, terahertz time-domain near-field microscopic imaging, terahertz communication, and so on.

Reliability of SiC MOSFETs in the High Cycle Fatigue Regime under Fast Power Pulses

Device reliability is an important factor in application, especially in the field of electric mobility. In this paper high cycle fatigue power cycling results of SiC devices in baseplate free modules are presented. To minimize testing time, the devices were stressed with load pulses corresponding to a 50 Hz load. The reliability results are the first fatigue results for temperature swings below 30 K for SiC devices. The lifetime in the high cycle fatigue area is limited by solder fatigue for high virtual junction temperatures of 150 °C. In theory, the reliability should increase exponential since the elastic-plastic transition area is reached. The experiment revealed that the lifetime can still be described by the Coffin-Manson approach also in the high cycle fatigue area. It can be observed that the high junction temperatures weaken the stability of the solder layer, so no major lifetime increase can develop. The measured temperature data are additionally corrected by a three-dimensional (3D) simulation to ensure a validity of the results.

Integrated device for polarization-independent electro-optic modulation using a splitter-rotator structure

Integrated device for polarization-independent electro-optic modulation using a splitter-rotator structure

Efficient and stable perovskite mini-module via high-quality homogeneous perovskite crystallization and improved interconnect

The efficiency and stability of perovskite module devices are mainly limited by the quality of scalable perovskite films and sub-cells’ lateral contact. Here, firstly, we report constant low temperature substrate to regulate the growth of perovskite intermediate films to slow down the crystallization for obtaining high-quality homogeneous perovskite films in large scale size, which avoid the effect of the ambient temperature on the film quality. Secondly, a scribing step named P1.5 was added before the top function layers deposition, the diffusion barrier layer can be formed “naturally” at the interconnection interface without introducing any additional materials, which well alleviates the diffusion degradation process. As a result, our inverted perovskite devices exhibit a very small efficiency loss with area expansion comparable to other photovoltaic devices (for example, Cadmium Telluride), the perovskite module (aperture area 14.61 cm2) shows a certified quasi-steady-state power conversion efficiency of 22.73%, and the module maintaining over 90% of its initial efficiency after 1000 hours of continuous operation under illumination.

Comprehensive two-dimensional gas chromatography using a miniaturized multiloop splitter-based non-cryogenic artificial trapping (M-SNAT) modulation device for analysis of cannabis samples

Multiloop splitter-based non-cryogenic artificial trapping (M-SNAT) modulation technique was developed, miniaturized and applied in comprehensive two-dimensional gas chromatography (GC×GC) for analysis of cannabis samples. The approach employed deactivated fuse silica (DFS) columns configured into multiple loop splitter system halving the perimeters of the progressively upstream loops. This splitter device was located between the first (1D) semi-nonpolar column outlet and a microfluidic Deans switch (DS). Each splitter loop splits a peak into two subpeaks having the same area with different void times. Three loops were then applied resulting in the number of the split subpeaks (nsplit) of 8 for each peak, and retention time differences between any two adjacent subpeaks (∆tR,split) were the same. By applying periodic heartcut event (H/C) within every artificial modulation period (PAM) of nsplit×∆tR,split, comprehensive split-and-trapped modulation profiles of analytes could be selectively transferred onto the second (2D) polar column (30 m) without cryogen consumption. This artificial modulation system was applied for analysis of cannabis samples with enhanced 2D peak capacity (2nc∼15). The established method was applied to analyse cannabis extracts using vegetable oils with or without frying process. This reveals 454 different peaks with 76, 92, 35 and 70 specific components specifically observed by using olive oil extraction (OE), fried OE, coconut oil extraction (CE) and fried CE, respectively.

Improvement of the technique of positioning the endocardial electrodes of the cardiac contractility modulation device in patients with CHF with reduced ejection fraction and atrial fibrillation

To evaluate the efficacy and safety of the advanced technique for positioning the endocardial electrodes of a cardiac contractility modulation (CCM) device. The CCM system was implanted in 100 patients, of which 60 CCM electrodes were positioned in the most optimal zones of myocardial perfusion, in particular, in the zone of the minor focal-scar/fibrotic lesion (the Summed Rest Score of 0 to 1-2, the intensity of the radiopharmaceutical at least 30%), and in 40 patients according to the standard procedure. Before the implantation of the CCM system, 60 patients underwent tomography (S-SPECT) of the myocardium with 99mTc-methoxy-isobutyl-isonitrile at rest to determine the most optimal electrode positioning zones and 100 patients underwent transthoracic echocardiography at baseline and after 12 months to assess the effectiveness of surgical treatment. Improved ventricular electrode positioning technique is associated with the best reverse remodeling of the left ventricular myocardium, especially in patients with ischemic chronic heart failure, with less radiation exposure to the surgeon and the patient, and without electrode-related complications. At the preoperative stage, it is recommended to perform a synchronized single-photon emission computed tomography of the myocardium with 99mTc-methoxy-isobutyl-isonitrile at rest before implantation of the CCM device to assess the presence of scar zones/myocardial fibrosis in the anterior and inferior septal regions of the interventricular septum of the left ventricle, followed by implantation of ventricular electrodes in the zone of the minor scar/fibrous lesion, which will allow to achieve optimal stimulation parameters, increase the effectiveness of CCM therapy, reduce the radiation exposure on medical personnel and the patient during surgery.