Pulse Generator Research Articles

Low-voltage DC-DC off-grid PV system: various irradiance studies

The off-grid photovoltaic (OGPV) system, also referred to as a stand-alone power system, generates electricity from solar energy independently of the main electricity grid. However, photovoltaic (PV) modules face limitations in consistently providing the necessary voltage. Thus, a DC-DC converter is employed to adjust the voltage to match the requirements of the load. This paper proposes a detailed analysis of irradiance patterns resembling in-lab and real-world conditions to address the challenge of selecting the optimal DC-DC OGPV system capable of functioning effectively under standard test condition (STC) and dynamic test condition (DTC), respectively. Three proposed irradiance analyses, tailored to different environmental scenarios, aim to identify output performances for DC-DC OGPV system which are aligning with standards set by the International Electrotechnical Commission (IEC) 61727. The DC-DC OGPV system is simulated using MATLAB Simulink. Furthermore, comparative studies involving different PV module types and several switching techniques (pulse generator and maximum power point tracking or MPPT implementations), where findings are instrumental in advancing the development and projection planning for medium to high-voltage OGPV systems, contributing to the global initiative for accessible and sustainable energy solutions aligned with sustainable development goal (SDG 7).

Predictive Current Control and Current Balance Method for Interleaved Buck EDM Pulse Generator

Predictive Current Control and Current Balance Method for Interleaved Buck EDM Pulse Generator

Bismuth telluride as a passive Q-switcher for neodymium-doped fiber laser

The scene of fiber laser has progressed very rapidly with the demonstration of various materials as saturable absorbers in a near- and mid-infrared laser cavity. However, the researchers focused on erbium-, ytterbium-, and thulium-doped fiber as a gain medium. Here, we proposed a neodymium-doped fiber laser setup to generate a Q-switched laser in a 1-μm regime. The laser utilized bismuth telluride, a topological insulator as a Q-switcher for pulse generation. With a linear absorption of approximately 5 dB at 1089 nm, this SA can generate a stable Q-switched laser in a neodymium-doped fiber laser cavity. It generates a stable Q-switched laser at 1089 nm when the pump intensity is adjusted between 167 and 190 mW. The pulsed laser owns the shortest pulse width of 6.48 μs with a maximum repetition rate of 40 kHz. The stability of the laser is promising since it has a signal-to-noise ratio of 40 dB. In the authors’ knowledge, this is the first demonstration of bismuth telluride as a saturable absorber in an all-fiberized neodymium-doped fiber laser cavity.

Low cost pulsed electric field generator using DC-DC boost converter and capacitor diode voltage multiplier

Traditional high-voltage pulse generators, like Marx generators often face challenges related to efficiency and complexity. In this paper, a solid-state multi-module high-voltage pulse generator that integrates capacitor-diode voltage multipliers (CDVM) with DC-DC boost converters and closed-loop voltage control is proposed to overcome these challenges. The system achieves high output voltage by coupling the pulsed output voltages of individual low-voltage DC sources in series across each module. The proposed design was modeled using MATLAB, and experimental testing was conducted on a single stage. Comparative analyses between timedomain parameters, proportional-integral (PI), and fractional order proportional integral derivative (FOPID) controllers were performed. Both MATLAB simulations and experimental validations demonstrate the effectiveness of this approach. The rise time, peak time, settling time, and steady-state error are all improved using an FOPID controller, decreasing from 0.32 to 0.31 seconds, 0.42 to 0.35 seconds, and 3.15 to 2.20 seconds, respectively. These findings indicate that a closed-loop FOPID controller enhances time-domain performance parameters more effectively than a PI controller for a two-stage DC-DC voltage multiplier.

An open-source, battery-powered, low-cost, and dual-channel pneumatic pulse generator for microfluidic cell-stretch assays

Cells in the body are regularly subjected to mechanical forces that influence their biological fate in terms of morphology, gene expression, and differentiation. The current gold standard method to replicate these effects in vitro is to culture cells on devices with elastic substrates and to impart mechanical stretch using mechanical or pneumatic pull–push methods. Microfluidic device designs offer several advantages in this context for general uniform and controlled stretching. However, the experimental setups are bulky, not user-friendly, and often involve several components that reside outside of the tissue culture incubator. Given the wide utility of mechanical stimulation in in-vitro research, our aim was to create a turn-key research tool that bioengineers can deploy in their cell-stretch assays, without having to deal with the complexity and nuances of ad hoc experimental setups. Here, we present an open-source, battery-powered, dual-channel cyclic pneumatic pulse generator box that can reside within an incubator and is compatible with custom microfluidic cell stretch devices. Our method depends on generating pressure-vacuum pulses simply using a linear miniature pneumatic air cylinder actuated using a continuous servo motor. To the best our knowledge, this is a first example of a completely battery-powered, standalone system that doesn’t have any peripherals residing out of the incubator. We provide a detailed list of different components as well as the step-by-step assembly process. We validate its performance in a cell stretch assay using a commercially available microfluidic chip. Our results show an acute stimulation of cyclic stretching over 8 h on human umbilical vein endothelial cells (HUVECs) resulted in preferential alignment of cells perpendicular to the axis of stretch.

Nanosecond Pulse Generator Based on Inductive Energy Storage Forming Line With Impedance Matching Modulation Capability

Nanosecond Pulse Generator Based on Inductive Energy Storage Forming Line With Impedance Matching Modulation Capability

Perioperative direct oral anticoagulant management during cardiac implantable electronic device surgery: an updated systematic review and meta-analysis.

Patients undergoing cardiovascular implantable electronic device (CIED) implantation are often on direct oral anticoagulation (DOAC). However, the evidence on whether to continue or temporarily discontinue DOAC therapy during the perioperative period in these patients is unclear. We conducted a comprehensive literature review using PubMed, Embase, and Cochrane databases through July 2024. We included studies comparing uninterrupted versus interrupted perioperative DOAC therapy in patients undergoing CIED procedure- primary implants, pulse generator replacement, and device upgrades. Primary outcomes were clinically significant device-pocket hematoma and thromboembolic events. Secondary outcomes included any device-pocket hematoma, all-cause mortality, major bleeding, and any bleeding. A total of 1,607 patients from 8 studies were included. The mean age was 73.2years, with atrial fibrillation as the indication for DOAC therapy in most patients. The mean CHA2DS2-VASc was 3.4. Among the included studies, 2 were randomized control trials (RCTs), while the others were observational cohort studies, including one that was propensity score matched. Our meta-analysis found both strategies to be similar in terms of clinically significant pocket hematoma (RR 1.70; 95%CI 0.84-3.45; p = 0.14; I2 = 0%), thromboembolic complications (RR 0.35; 95%CI 0.04-3.32; p = 0.36; I2 = 19%), any pocket hematoma, all-cause mortality and any bleeding with a higher risk of major bleeding with uninterrupted anticoagulation. This meta-analysis shows that uninterrupted DOAC therapy is comparable to interrupted therapy for CIED procedures, with a potential increase in major bleeding risk but low overall complication rates. Further research is needed to confirm the best approach of periprocedural anticoagulation in these patients.

Wavelength-tunable high-repetition-rate pulse generation in a SOA-based fiber laser with gain instability

Abstract Introducing negative optical feedback into a semiconductor optical amplifier-based laser presents a straightforward and effective approach for generating high-repetition-rate pulses through the mechanism of self-sustaining cross-gain modulation. In this work, we demonstrate, for the first time, the tunability of high-frequency pulse generation over a wide wavelength range by adjusting the central transmission wavelength of a tunable filter. Our laser system achieved a full tuning range from 1480 nm to 1556 nm (76 nm) while maintaining pulsed lasing. Remarkably, the laser exhibited a maximum pulse contrast exceeding 85% over a tuning range of 43 nm, from 1505.7 nm to 1548.7 nm. At any wavelength within this range, stable, self-starting pulse generation was consistently achieved, with a pulse repetition rate of 1.3 GHz.

Generation of dark pulses in mode-locked erbium-doped fiber ring laser using Ti2SnC absorber

Abstract We report the experimental observation of domain-wall type dark solitons in an all-fiber ring cavity erbium-doped fiber laser (EDFL) mode-locked with a Titanium Tin Carbide (Ti2SnC) saturable absorber (SA). The SA, featuring a modulation depth of 8.2%, was created by incorporating Ti2SnC particles into a polyvinyl film. Dark pulse formation is attributed to cross-phase coupling resulting from cavity birefringence. The mode-locked laser operates at 1559 nm with pump power ranging from 30.9 mW to 90.0 mW, achieving a maximum pulse energy of 1.73 nJ, a repetition rate of 1.78 MHz, and a pulse width of 261.2 ns.

Phase-coded coherent microwave pulse generation based on actively mode-locked optoelectronic parametric oscillator

Phase-coded coherent microwave pulse generation based on actively mode-locked optoelectronic parametric oscillator

Plasmonic gold-enhanced GaAs for femtosecond laser generation

Surface plasmon resonance (SPR) can significantly enhance the local electromagnetic fields, facilitating the interaction between light and matter at the nanoscale. However, its ultrafast photonics application in lasers remains unexplored, especially for femtosecond pulsed laser generation. In this work, we investigate the femtosecond pulse generation based on SPR-enhanced nonlinear absorption characteristics in GaAs for the first time, to the best of our knowledge. The gold nanoparticles (GNPs)+GaAs bilayer saturation absorber (SA) decorated on the tapered fiber generates a modulation depth of 2.02% and a saturable intensity of 3.13 MW/cm2. Stable mode-locked pulses can be obtained in an erbium-doped fiber cavity, as demonstrated here. The signal-to-noise ratio (SNR) of the pulses is 75 dB and the shortest pulse duration can reach 384 fs, highlighting the potential of the SPR effect in manufacturing ultrafast optical devices.

Generation and applications of high-order harmonics and attosecond pulses in solids

Generation and applications of high-order harmonics and attosecond pulses in solids

180 mW, 1 MHz, 15 fs carrier-envelope phase-stable pulse generation via polarization-optimized down-conversion from gas-filled hollow-core fiber

Gas-filled hollow core fibers allow the generation of single-cycle pulses at megahertz repetition rates. When coupled with difference frequency generation, they can be an ideal driver for generating carrier-envelope phase stable, octave-spanning pulses in the short-wavelength infrared. In this work, we investigate the dependence of the polarization state in gas-filled hollow-core fibers (HCF) on the subsequent difference frequency generation stage. We show that by adjusting the input polarization state of light in geometrically symmetric systems, such as hollow-core fibers, one can achieve precise control over the polarization state of the output pulses. This manipulation preserves the temporal characteristics of the generated ultrashort pulses, especially when operating at a near single-cycle regime. We leverage this property to boost the downconversion efficiency of the near single-cycle pulses in a type I difference frequency generation stage. Our technique overcomes the bandwidth and dispersion constraints of the previous methods that rely on broadband waveplates or adjustment of crystal axes relative to the laboratory frame. This advancement is crucial for experiments demanding pure polarization states in the eigenmodes of the laboratory frame.

Differential target multiplexed spinal cord stimulation in patients with Persistent Spinal Pain Syndrome Type II: a study protocol for a 12-month multicentre cohort study (DETECT)

IntroductionDifferential target multiplexed spinal cord stimulation (DTM SCS) is a new stimulation paradigm for chronic pain management with the aim of modulating glial cells and neurons in order to rebalance...

Biological and hardware-related spinal cord stimulation complications and their management: A single-center retrospective analysis of the implantation of nonrechargeable implantable pulse generators in different pain conditions

Biological and hardware-related spinal cord stimulation complications and their management: A single-center retrospective analysis of the implantation of nonrechargeable implantable pulse generators in different pain conditions

Generation of mode-locked pulses assisted by reduced graphene oxide/cerium oxide (rGO/CeO2) embedded in arc-shaped fiber

Abstract This study demonstrates the synthesis of a reduced graphene oxide/cerium oxide (rGO/CeO2) composite and its successful use as a saturable absorber (SA) in ultrafast photonics. The rGO/CeO2 composite was synthesized using a facile hydrothermal approach, and an arc-shaped fiber was fabricated using a polishing technique. The arc-shaped fiber employed indirect evanescent field coupling, allowing interaction between the composite material and the laser, which facilitated the generation of mode-locked pulses. An arc-shaped fiber drop-casted with rGO/CeO2 was connected to a 2.0 µm laser source, achieving a modulation depth of 50.16%. The emitted laser pulses have a duration of 1.776 ps, an operational wavelength of 1904 nm, and a spectral bandwidth (FWHM) of 2.76 nm. The pulse energy was 89.36 pJ with a high signal-to-noise ratio (SNR) of 63 dB. This study introduces rGO/CeO2 embedded in an arc-shaped fiber as an effective SA, exhibiting favorable nonlinear optical absorption in the near 2.0 µm wavelength region, making it suitable for applications in ultrafast photonics.

Generation of sub-30 fs pulses from an erbium-doped fiber amplifier at 203 MHz repetition rate

Generation of sub-30 fs pulses from an erbium-doped fiber amplifier at 203 MHz repetition rate

A Robust Low‐Power Power‐On‐Reset Circuit With Dual Threshold Method

ABSTRACTIn this paper, a robust low‐power power‐on‐reset (POR) circuit with dual threshold method is proposed. The current‐based circuit exhibits good robustness with respect to process, voltage, temperature, and supply ramp variations. In contrast to conventional delay‐based pulse generation approaches, a dual threshold method is introduced to generate POR and brown‐out‐reset (BOR) pulse signals, resulting in ultralow quiescent current and a compact area. Implemented in the 55‐nm CMOS process, the proposed circuit achieves an accurate trigger‐point voltage with a temperature coefficient of 90.4 ppm/°C and a deviation to the ramp time of 2.9% for a range from 100 μs to 1 s. Furthermore, the quiescent current and active area are 0.3 nA and 4834 μm2, respectively, making it particularly suitable for energy harvesting systems.

Optical pulse generation with programmable positions in an actively mode-locked optical cavity.

A novel, to our knowledge, approach for generating optical pulses with programmable positions in an actively mode-locked (AML) optical cavity is proposed and experimentally demonstrated. In the AML, active mode locking occurs when the cavity gain exceeds one, and the cavity round trip time equals integer multiples of the repetition period of the electrical driving signal. The generated optical pulses are present at the positions where the optical cavity operates at its maximum transmission points. By periodically controlling the cavity gain with the driving signal, the maximum transmission points can be manipulated using a periodic arbitrary waveform, allowing the positions of the generated optical pulses within one round trip time to be programmed. Thanks to the superposition of the circulating optical field within the optical cavity, the pulse width of the generated pulses can be greatly compressed. In a proof-of-concept experiment, optical pulses with programmable pulse numbers, pulse intervals, and pulse position distributions in one period are generated by programming the driving signals. Optical pulse compression is also successfully verified. Optical pulses with an approximate 34-ps pulse width, ultra-low pulse interval (about 200 ps), and linear positional distribution are achieved.

Long-term clinical outcomes of remote monitoring for implantable cardioverter-defibrillators in Singapore.

Remote monitoring (RM) for cardiac implantable electronic devices is on the rise and has been shown to reduce the burden of in-clinic follow-up visits. We aimed to investigate the long-term clinical outcomes of RM versus no RM. This was a prospective, single-centre cohort study of consecutive patients with an implantable cardioverter-defibrillator (ICD) or cardiac resynchronisation therapy-defibrillator (CRT-D) followed up from 2018 to 2023. Patients who received non-ICD devices were excluded. In general, RM was offered to all patients, but uptake depended on patient preference. For data analysis, patients were stratified according to whether RM was used. The primary outcome was all-cause mortality; secondary outcomes were hospitalisation for heart failure and device therapy (shocks and electrical storm). Of 551 patients, 284 (51.5%) received RM and 267 (49.5%) did not. Baseline demographics were similar between the two arms. All-cause mortality was significantly lower in RM versus non-RM patients (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.33-0.60, P <0.001), as was hospitalisation for heart failure (HR 0.39, 95% CI 0.25-0.59, P <0.001); these remained significant after adjustment for baseline covariates. More patients on RM received appropriate antitachycardia pacing (ATP) (17.6% vs. 10.7%, P = 0.035) and appropriate shocks (24.1% vs. 14.7%, P = 0.017). The incidences of inappropriate ATP, inappropriate shocks and electrical storm were similar. More patients on RM underwent pulse generator change (34.1% vs. 10.1%, P <0.001). Remote monitoring was associated with significantly lower mortality in both ICDs and CRT-Ds and in primary and secondary indications, as well as fewer heart failure hospitalisations. This supports current guidelines recommending the use of RM in all patients with ICD or CRT-D.