Pulse Generator Research Articles

Research on the key techniques of composite processing of EDM and vibration ultrasonic drilling

PurposeUtilizing electrical discharge machining (EDM) to process micro-holes in superalloys may lead to the formation of remelting layers and micro-cracks on the machined surface. This work proposes a method of composite processing of EDM and ultrasonic vibration drilling for machining precision micro-holes in complex positions of superalloys.Design/methodology/approachA six-axis computer numerical control (CNC) machine tool was developed, whose software control system adopted a real-time control architecture that integrates electrical discharge and ultrasonic vibration drilling. Among them, the CNC system software was developed based on Windows + RTX architecture, which could process the real-time processing state received by the hardware terminal and adjust the processing state. Based on the SoC (System on Chip) technology, an architecture for a pulse generator was developed. The circuit of the pulse generator was designed and implemented. Additionally, a composite mechanical system was engineered for both drilling and EDM. Two sets of control boards were designed for the hardware terminal. One set was the EDM discharge control board, which detected the discharge state and provided the pulse waveform for turning on the transistor. The other was a relay control card based on STM32, which could meet the switch between EDM and ultrasonic vibration, and used the Modbus protocol to communicate with the machining control software. FindingsThe mechanical structure of the designed composite machine tool can effectively avoid interference between the EDM spindle and the drilling spindle. The removal rate of the remelting layer on 1.5 mm single crystal superalloys after composite processing can reach over 90%. The average processing time per millimeter was 55 s, and the measured inner surface roughness of the hole was less than 1.6 µm, which realized the micro-hole machining without remelting layer, heat affected zone and micro-cracks in the single crystal superalloy.Originality/valueThe test results proved that the key techniques developed in this paper were suite for micro-hole machining of special materials.

Isolated attosecond pulse generation in a semi-infinite gas cell driven by time-gated phase matching

Isolated attosecond pulse (IAP) generation usually involves the use of short-medium gas cells operated at high pressures. In contrast, long-medium schemes at low pressures are commonly perceived as inherently unsuitable for IAP generation due to the nonlinear phenomena that challenge favourable phase-matching conditions. Here we provide clear experimental evidence on the generation of isolated extreme-ultraviolet attosecond pulses in a semi-infinite gas cell, demonstrating the use of extended-medium geometries for effective production of IAPs. To gain a deeper understanding we develop a simulation method for high-order harmonic generation (HHG), which combines nonlinear propagation with macroscopic HHG solving the 3D time-dependent Schrödinger equation at the single-atom level. Our simulations reveal that the nonlinear spatio-temporal reshaping of the driving field, observed in the experiment as a bright plasma channel, acts as a self-regulating mechanism boosting the phase-matching conditions for the generation of IAPs.

All-optical generation of full-range symmetry-tunable triangular-shaped pulses via wavelength multiplexing

A novel, to the best of our knowledge, all-optical approach for generating full-range symmetry-tunable triangular-shaped pulses through wavelength multiplexing is proposed and experimentally demonstrated. Two light-waves with a specified wavelength interval are injected in parallel into two commercial push–pull Mach–Zehnder modulators (MZMs) to carry the baseband radio frequency input. A tunable optical delay line (ODL) followed by one MZM is utilized to introduce the desired phase shift. By multiplexing the modulated signals carried on two wavelengths, triangular-shaped pulses can be achieved by the opto-electronic conversion. In this approach, by simply adjusting the DC bias voltages and the delay time offered by ODL, the triangular-shaped pulse with any self-defined symmetrical coefficient can be obtained. A complete theoretical analysis on the operation principle is presented and verified. The triangular-shaped pulses with full-range tunable symmetrical coefficients at the repetition rate of 5 GHz are successfully generated. This approach features all-optical architecture, ultra-wide system bandwidth, full-range tunable symmetry (0%–100%) and excellent reconfigurability, which are highly desired for the high-performance triangular-shaped pulse generator.

Polarization-diverse soliton transitions and deterministic switching dynamics in strongly-coupled and self-stabilized microresonator frequency combs

Dissipative Kerr soliton microcombs in microresonators have enabled fundamental advances in chip-scale precision metrology, communication, spectroscopy, and parallel signal processing. Here we demonstrate polarization-diverse soliton transitions and deterministic switching dynamics of a self-stabilized microcomb in a strongly-coupled dispersion-managed microresonator driven with a single pump laser. The switching dynamics are induced by the differential thermorefractivity between coupled transverse-magnetic and transverse-electric supermodes during the forward-backward pump detunings. The achieved large soliton existence range and deterministic transitions benefit from the switching dynamics, leading to the cross-polarized soliton microcomb formation when driven in the transverse-magnetic supermode of the single resonator. Secondly, we demonstrate two distinct polarization-diverse soliton formation routes – arising from chaotic or periodically-modulated waveforms via pump power selection. Thirdly, to observe the cross-polarized supermode transition dynamics, we develop a parametric temporal magnifier with picosecond resolution, MHz frame rate and sub-ns temporal windows. We construct picosecond temporal transition portraits in 100-ns recording length of the strongly-coupled solitons, mapping the transitions from multiple soliton molecular states to singlet solitons. This study underpins polarization-diverse soliton microcombs for chip-scale ultrashort pulse generation, supporting applications in frequency and precision metrology, communications, spectroscopy and information processing.

Dependence of Pressure Characteristics of Pressurized Pulse Water Jet Chamber on Nozzle Diameter

The nozzle is the key element of the water jet generator for energy conversion. In order to explore the influence of the nozzle diameter on the pressure characteristics of the supercharged pulsed water jet plenum chamber, a supercharged pulsed water jet pressure acquisition system was established, and the equations of motion and theoretical pressurization ratio equations of the supercharged pulsed water jet generator were established. The pressurization chamber pressure acquisition experiments under different nozzle diameters were carried out. The research results show that the pressurized pulsed water jet generator has a critical nozzle diameter of 0.6 mm. When the nozzle diameter is less than the critical diameter, the pressure in the boost chamber is equal to the product of the driving pressure and the boost ratio. As the nozzle changes, there is no significant change in the peak pressure and frequency of the boost chamber. When the nozzle diameter is greater than the critical diameter, there is a non-linear relationship between the boost chamber pressure and the driving pressure. As the nozzle diameter gradually increases, the actual boost ratio gradually decreases, and the peak pressure of the boost chamber further decreases. The nozzle diameter can no longer provide a load for the establishment of fluid pressure in the boost chamber. The results of this research provide a research basis for further controlling the pressure characteristics of the boost pulse water jet.

Successful spinal cord stimulation using fast-acting sub-perception therapy for postoperative neuropathic pain of syringomyelia with Chiari malformation type 1: a case report and literature review

BackgroundCentral neuropathic pain after foramen magnum decompression (FMD) for Chiari malformation type 1 (CM-1) with syringomyelia can be residual and refractory. Here we present a case of refractory central neuropathic pain after FMD in a CM-1 patient with syringomyelia who achieved improvements in pain following spinal cord stimulation (SCS) using fast-acting sub-perception therapy (FAST™).Case presentationA 76-year-old woman presented with a history of several years of bilateral upper extremity and chest-back pain. CM-1 and syringomyelia were diagnosed. The pain proved drug resistant, so FMD was performed for pain relief. After FMD, magnetic resonance imaging showed shrinkage of the syrinx. Pain was relieved, but bilateral finger, upper arm and thoracic back pain flared-up 10 months later. Due to pharmacotherapy resistance, SCS was planned for the purpose of improving pain. A percutaneous trial of SCS showed no improvement of pain with conventional SCS alone or in combination with Contour™, but the combination of FAST™ and Contour™ did improve pain. Three years after FMD, percutaneous leads and an implantable pulse generator were implanted. The program was set to FAST™ and Contour™. After implantation, pain as assessed using the McGill Pain Questionnaire and visual analog scale was relieved even after reducing dosages of analgesic. No adverse events were encountered.ConclusionPercutaneously implanted SCS using FAST™ may be effective for refractory pain after FMD for CM-1 with syringomyelia.

Complex dynamics in nonlinear small time-delayed optoelectronic oscillator and application in fast reservoir computing and pulse generation

We investigated a time-delayed optoelectronic oscillator (OEO) that displays a wide range of complex dynamic behavior under small time delay. The phase-space trajectory distributions in different dynamic regimes were compared which brings a new perspective on the underlying mechanism of the transition process. It was found that bifurcation is always possible no matter how small the time delay is even if the universal adiabatic approximation model is invalid. Hereby we proposed a versatile simple oscillator which has a potential capacity as memory carrier and high-dimensional state spatial mapping ability that brings 1000 times computing-efficiency improvements of reservoir computing over the large time delay one. Furthermore, we demonstrated a new approach for a tunable optoelectronic pulse generator (repetition rate at 0.2 MHz and 0.25 GHz) which depends critically on time-delayed input electrical pulse. The proposed oscillator is also a promising system for the applications of fast chaos-based communication.

Harnessing tin phthalocyanine for ultrafast mode-locking in an erbium-doped fiber laser

We present the first demonstration, to the best of our knowledge, of a mode-locked erbium-doped fiber laser (EDFL) employing tin phthalocyanines (SnPc) as a saturable absorber (SA). The investigated SA exhibits a notable modulation depth of 18.6%, fabricated via a simple, cost-effective method, wherein the SnPc compound is embedded into a polyvinyl alcohol (PVA) film. Integration of this thin film into the EDFL cavity facilitates the generation of output pulses with a repetition rate of 0.96 MHz and a pulse duration of 2.68 ps. The frequency spectrum showcases a signal-to-noise ratio of up to 73.2 dB, affirming the stability of the mode-locking operation. Operating at a wavelength of 1531.7 nm, this picosecond pulse train holds significant promise for diverse applications, including high-precision optical metrology, frequency-comb generation, and broadband absorption spectroscopy.

Device-Related Reoperations 8 Years Following Sacral Neuromodulation Implantation in Older Women.

The objective was to describe long-term device-related reoperations at 8years following sacral neuromodulation (SNM) in women older than 65years for the indications of overactive bladder (OAB), fecal incontinence (FI), and/or idiopathic urinary retention (UR). The 2010-2019 Medicare 100% Outpatient Limited Dataset was used to identify women aged 65years and older who underwent SNM to treat OAB, FI, and/or UR. The primary study outcome was any device-related reoperation within 8years following initial implantable pulse generator (IPG) implantation defined as: IPG revision or removal; IPG replacement; or neuro-electrode revision or removal. Kaplan-Meier survival analysis was also performed to evaluate time to adverse event. The cohort included 32,454 women with a mean age of 74years. The most common indication for SNM was OAB (71%) followed by UI and FI (13%) and FI only (8%). Staged SNM procedures were performed more frequently (60%) than percutaneous nerve evaluation/full implants. The overall rate of device-related reoperations was 24% over 8years: 12% of patients underwent removal or revision of the neuro-electrode, 11% underwent removal or revision of the IPG, and 13% underwent replacement of the IPG. The mean follow-up was 3.9 ± 2.4years. The cumulative incidence of any device-related reoperations was 9.4% at 1year, 20% at 3years, and 43% at 8years. In the 8years following SNM implantation, the rate of device-related reoperation among female Medicare beneficiaries was 43%, and staged implants were associated with a 17% lower likelihood of undergoing any device-related reoperations.

Generation and evolution dynamics of gain-guided dissipative solitons in a Tm-doped fiber laser

The generation of dissipative solitons from a mode-locked fiber laser can enhance emission energy, while the insertion of a bandwidth filter exposes the system to complexity. This study presents the first generation and evolution dynamics of gain-guided dissipative solitons (GGDSs) in Tm-doped fiber lasers exploiting the finite gain bandwidth. The results highlight the intricate interplay of finite gain bandwidth with dispersion and nonlinearity in governing the dynamics of GGDSs. An increase in pump power significantly broadens the emission spectrum, which in turn introduces the finite gain bandwidth to the generation of GGDSs. Consequently, linear chirp accumulates, promoting high-energy ultrashort pulse generation after external compression. However, an increase in round-trip group delay dispersion leads to a narrower spectral bandwidth, which can weaken the influence of the finite gain bandwidth, resulting in decreased soliton energy and broader pulse duration. The investigation of GGDS evolution dynamics within the cavity also provides us with a deeper insight into the characteristics of GGDS. Overall, this research offers important guidance for designing high-performance Tm-doped fiber lasers with simple structures that fully exploit the finite gain bandwidth.

Mo4/3B2T2/Co3O4 vdW heterostructure as saturable absorber for ultrafast pulse generation

VdW heterostructure have garnered significant interest in ultrafast laser generation because of their attractive saturable absorption properties, holding promise for applications in optics, medicine, and optoelectronics. In this study, the saturable absorption of Mo4/3B2T2/Co3O4 vdW is investigated for the first time. Mo4/3B2T2/Co3O4 vdW SA is successfully applied to passively mode-locked Er-doped fiber lasers. Due to the excellent saturable absorption properties of Mo4/3B2T2/Co3O4 vdW SA, stable mode-locked fiber lasers can be realized in the same cavity, including fundamentally conventional soliton, bound soliton, and harmonic soliton. Among them, the conventional soliton operates at a repetition rate of 11.16 MHz with a high SNR of 56.26 dB. Bound soliton is observed with a soliton pulse separation of 5.26 ps. Furthermore, 3rd-, 5th-, 8th-, 10th-, 12th-, 15th-, and 17th-order harmonic solitons are observed, corresponding to repetition rates of 33.48 MHz, 55.8 MHz, 89.28 MHz, 111.6 MHz, 133.92 MHz, 167.4 MHz and 189.72 MHz, respectively. For vdW heterostructure, the saturable absorption properties are strongly modulated by the interlayer coupling, which may be introduced by the Fermi level recombination and photogenerated carrier migration between the heterostructure. We established a model to understand the saturable absorption properties of the Mo4/3B2T2/Co3O4, which suggests the enhancements of the saturable absorption are attributed to the carrier migration between Mo4/3B2T2 and Co3O4. The results indicate that Mo4/3B2T2/Co3O4 vdW heterostructure can be used as an excellent nonlinear optical material, which can be used as SA in ultrafast pulse generation.

Dynamic analysis and manipulation of self-starting single-pulse mode-locking in a Yb-doped fiber laser with Figure-9 all-normal-dispersion

The self-starting single-pulse mode-locked mechanisms in an all-normal-dispersion (ANDi) Figure-9 fiber laser are portrayed via an integrated simulation approach, which combines rate equations with the General Nonlinear Schrödinger Equation (GNLSE). The simulation results indicate that the mode-locking performances and pulse characteristics are significantly influenced by the splitting ratio, linear phase shift, gain, and asymmetric placement of gain fiber positions within the loop directly, providing effective quantified guidance for self-starting high-quality pulse generation. An experimental oscillation based on a nonlinear amplifying loop mirror (NALM) was established, operating under different widths of bandpass filters. Combining simulation for parameter optimization, the introduced linear phase shift and the coupling ratio were adjusted by changing the rotation angle of the combination wave plate to determine the optimal mode-locked operating point. A spectral bandwidth of 10.4 nm and a pulse duration of 17.5 ps, delivering 0.67 nJ of pulse energy, have been achieved in a modified mode-locked Yb-doped fiber laser.

High-Frequency Magnetic Pulse Generator for Low-Intensity Transcranial Magnetic Stimulation

This paper presents a high-frequency (HF) magnetic pulse generator designed for low-intensity transcranial magnetic stimulation (LI-TMS) applications. HF pulse stimulation can induce a strong electric field with minimal current and enhance the penetration depth of the electric field in human tissue. The HF magnetic pulse generator was designed and fabricated using a microcontroller unit, gate driver, full-bridge coil driver, and stimulation coil. Measurements with a full-bridge circuit supply voltage of 10 V demonstrated an electric field intensity of 6.8 Vpp/m at a frequency of 1 MHz with a power dissipation of 2.45 W. Achieving a similar electric field intensity at a frequency of 100 kHz required approximately ten times the coil current. Additionally, a quasi-resonant LC load was introduced by connecting a capacitor in series with the stimulation coil, which set the resonant frequency to approximately 10% higher than the frequency of 1 MHz. This approach reduced the coil impedance, achieving higher current with the same bias supply voltage. Experimental results showed an enhanced electric field intensity of 19.1 Vpp/m with a supply voltage of only 1.8 V and reduced power dissipation of 1.11 W. The proposed HF pulse train with quasi-resonant coil system is expected to enable a low-power LI-TMS system.

Patterns of persistence: Genetic and behavioral population complexity of winter flounder amid population declines.

Winter flounder Pseudopleuronectes americanus (Walbaum 1792) are a coastal flatfish species of economic and cultural importance that have dwindled to <15, % of their historic abundance in the southern New England/Mid-Atlantic region of the United States, with evidence indicating near-extirpation of certain local populations. This species exhibits intricate behaviors in spawning and migration that contribute to population complexity and resilience. These behaviors encompass full or partial philopatry to natal estuaries, the generation of multiple pulses of larval delivery, and partial migration. The patterns of genetic diversity within and among estuaries and cohorts presented here carry important implications in understanding the susceptibility to demographic shocks, even if the full extent of genetic diversity within and among winter flounder stocks on the US East Coast remains unresolved. Our findings reveal connectivity between estuaries in Long Island, New York, suggesting the potential for genetic rescue of depleted subpopulations. Family reconstruction and relatedness analysis indicate that split cohorts and migration contingents are not the result of genetically distinct lineages. We found no evidence for genetic structure separating these groups, and in some instances, we were able to detect closely related individuals that belonged to different migratory contingents or cohorts. Characterizing the spatial and behavioral organization of this species at the population level is crucial for comprehending its potential for recovery, not only in terms of biomass but also in reinstating the complex population structure that supports resilience. The search for generality in winter flounder spawning and migration behavior remains elusive, but perhaps the lack of generalities within this species is what has allowed it to persist in the face of decades of environmental and anthropogenic stressors.

Direct-modulation optoelectronic oscillator for optical pulse and frequency comb generation

We report the generation of an optical pulse train with a 10 GHz repetition rate in a dual loop direct-modulation optoelectronic oscillator (OEO). Pulse generation is achieved using nonlinear compression in the OEO 5-km-long optical delay line. 3 ps pulses with a timing jitter of 13 fs are reported, while the OEO maintains a phase noise of −133dBc/Hz at 10 kHz from the carrier. Two architectures are compared experimentally and theoretically. A frequency comb with a 1.2 THz linewidth at −30dB is generated.

Replication of Radial Pulses Using Magneto-Rheological Fluids.

The radial pulse is a critical health marker with expanding applications in wearable technology. To improve these applications, developing a pulse generator that consistently produces realistic pulses is crucial for validation and training. The goal of this study was to design and test a cost-effective pulse simulator that can accurately replicate a wide range of age-dependent radial pulses with simplicity and precision. To this end, this study incorporated a magneto-rheological (MR) fluid device into a cam-based pulse simulator. The MR device, as a key component, enables pulse shaping without the need for additional cams, substantially reducing the cost and complexity of control compared with existing pulse simulators. To evaluate the performance of the MR pulse simulator, the root-mean-square (RMS) error criterion (less than 5%) was used to compare the experimentally obtained pulse waveform with the in vivo pulse waveform for specific age groups. After demonstrating that the MR simulator could produce three representative in vivo pulses, a parametric study was conducted to show the feasibility of the slope-based pulse-shaping method for the MR pulse simulator to continuously generate a range of age-related pulses.

Lightwave-controlled relativistic plasma mirrors.

We report on attosecond-scale control of high-harmonic and fast electron emission from plasma mirrors driven by relativistic-intensity near-single-cycle light waves at a kHz repetition rate. By controlling the waveform of the intense light transient, we reproducibly form a sub-cycle temporal intensity gate at the plasma mirror surface, leading to the observation of extreme ultraviolet spectral continua, characteristic of isolated attosecond pulse (IAP) generation. We also observe the correlated emission of a waveform-dependent relativistic electron beam, paving the way toward fully lightwave-controlled dynamics of relativistic plasma mirrors.

Gain-switched pulse generation of 5.3 ps from 30 GHz-modulation-bandwidth 1270 nm DFB laser diode: erratum.

We present an erratum to our Letter [Opt. Lett.48, 6344 (2023)10.1364/OL.510237]. This erratum corrects the error of Figs.3(b) and 4(b) made via incorrect scaling in the horizontal axes. The corrections have no influence on the main text and conclusions of the original Letter.

Antibiotic-impregnated envelopes reduce the rate of surgical site infection in deep brain stimulation pulse generators: a comparative study.

Deep brain stimulation (DBS) is a surgical procedure that has been used to treat a variety of neurological disorders including Parkinson's disease, essential tremor, and dystonia. While DBS is generally considered safe and effective, surgical site infections (SSIs) are a potential complication that can lead to significant morbidity and mortality. Our objective was to investigate the use of antibiotic-impregnated envelopes (AIEs) encasing implantable pulse generators (IPGs) to reduce the rate of infection at IPG sites and the costs. We conducted a retrospective analysis at a single center encompassing all procedures involving the placement of Implantable Pulse Generators (IPG), including both initial insertions and replacement surgeries. The study period spanned from January 2017 to May 2024. Starting in 2020, the routine utilization of AIE became standard practice at our institute for both primary DBS implantation and IPG replacements. Surgical techniques remained consistent, pre- and post-operative antibiotic protocols were standardized throughout the study period and all cases were undertaken by a single surgeon. 178 patients were included and the overall incidence of IPG SSIs was found to be 1.7% (1 infection in 58 patients; 20 primary IPG/38 IPG replacements) among those who received an AIE compared to 5% (6 infections in 120 patients; 36 primary IPG/84 replacement IPG) in patients where no AIE was utilized. This resulted in an odds ratio for infection that was 2.9 times higher in the absence of AIE. The decrease in infection rates was observed in both primary and replacement IPG implants. Notably, over 80% of patients with IPG infection required surgical intervention. The use of AIE further resulted in significant cost savings. To our knowledge, this is the largest series reporting the efficacy of Antibiotic impregnated envelope (AIE) in modifying infection rates associated with both initial and replacement Deep Brain Stimulation (DBS) Implantable Pulse Generators (IPGs). The implementation of AIEs led to a decrease in the occurrence of IPG-related infections, observed across both primary implantations and replacement surgeries, with associated economic benefits.

Readout studies for the HIKE main electromagnetic calorimeter

The High-Intensity Kaon Experiment (HIKE) is a proposed future kaon experiment designed for the CERN SPS accelerator. To cope with a planned increase of beam intensity by a factor of 4 with respect to the current NA62 experiment, the new Main Electromagnetic Calorimeter (MEC) has to provide a similar improvement in time resolution over the current Liquid Krypton calorimeter, down to ≈100ps for a 40GeV photon, while maintaining a comparable energy and spatial resolution. To achieve these goals, the planned detector consists of a shashlik calorimeter paired with high-resolution analog to digital converter for both energy deposit and arrival time estimates, operating at fast sample rates (∼1GHz).This contribution describes a prototype of the readout system using commercial “off-the-shelf” boards. In particular, we focused on feature extraction and tested it using a pulse generator. We included a data readout logic based on the TCP/IP protocol allows for easy deployment in beam tests.