Double Pulse Research Articles

Design and characterization of cell topology effect on SiC VDMOSFETs for high power and frequency applications

In this paper, we present a comprehensive investigation of the impact of cell topology and pitch reduction on the DC and AC characteristics of 1200V-rated 4H-SiC planar VDMOSFETs. We have designed and fabricated four different cell topologies, namely linear, square, hexagonal, and staggered cell, in order to characterize their performance. Among the various cell types, the hexagonal cell exhibits the most favorable specific on-state resistance (Ron,sp) value. However, it is worth noting that the breakdown values of both the hexagonal and staggered square cells fall significantly below the simulated values. This is attributed to the interaction between the irregular cell boundaries and the edge cell termination region. Furthermore, we observed that the linear cell has the highest gate resistance compared to the other cell types. Additionally, the linear cell also demonstrates a lower input capacitance than the other cells. This can be attributed to its longer gate trasmission line and smaller area. Lastly, we performed dynamic double pulse tests on the fabricated VDMOSFETs to compare their switching characteristics. It was concluded that linear cell VDMOS is suitable for high switching applications, while square, hexagonal and S.S cell VDMOS are better suited for lower switching applications that require a high output current.

Plasma evolution in laser powder bed fusion using a double pulse format: Time-resolved measurements and physics-based modeling

A novel laser powder bed fusion (LPBF) process utilizing a special double-pulse format was previously proposed. In this process, typically two different types of laser pulses are fired alternatively in time: the low-intensity “sintering laser pulses” intended to melt and coalesce particles, followed by the high-intensity “pressing laser pulse(s)” intended to induce plasma to generate high pressure onto the powder bed to suppress balling and enhance the densification of the sintered material. Laser-induced plasma plays a key role in the novel double-pulse LPBF process, but has not been studied sufficiently. Some critical questions remain to be better answered, such as: what is the minimum plasma-induced pressure needed to effectively suppress balling and how do the “sintering pulses” influence the plasma evolution? This paper reports a model-experiment integrative study of the plasma in DP-LMS, which is seldom reported in a paper in literature to the authors’ knowledge. The plasma evolution is observed in-situ with a high temporal resolution using an intensified CCD (ICCD) camera. The optical emission spectrum (OES) of the plasma is measured and the plasma temperature is deduced from the OES. A physics-based model for the plasma is developed by combining multiple modules. Under the investigated conditions, the model predictions show acceptable agreements with the measured plasma temperature and top front propagation. Utilizing the model, it has been found that under the conditions studied, the minimum plasma-induced pressure required to effectively suppress balling is approximately the pressure making the Weber number exceed ∼1 for the approximately analogized process of a droplet impacting a solid surface. The effect of the “sintering pulses” also influences the evolution of the plasma and obviously increase the plasma-induced pressure on the powder bed surface.

A Systematic Methodology for Parasitic Capacitance Estimation and Validation of Multichip Modules

This paper proposes a method for extracting parasitic capacitances from die terminals to baseplate in a multi-chip-module (MCM). The parasitic capacitors constitute the common mode (CM) equivalent circuit model enabling filter design. While traditionally simple open module die area measurements are used to calculate capacitance from concerned nodes to baseplate, such methods result in breaking the module or contamination, rendering the module useless. This is especially concerning for high voltage (HV) rated modules (> 10 kV) where cost can be a deciding factor. Hence, a non-intrusive double pulse test method is developed to extract the parasitic capacitance from specific nodes to ground without physical damage to the module. Consequently, the proposed method is verified using a series of tests and open module measurements. The distributed capacitors can be transformed into lumped capacitors for electromagnetic compatibility (EMC) simulations and filter design. The proposed method is analyzed on a Three-Level Neutral Point Clamped (3L-NPC) phase leg module and compared against traditional method. Finally, the impact of estimation errors on the proposed method are discussed.

A multiphysics SET modeling method based on machine learning

AbstractWith continuous downscaling of transistor sizes, the sensitivity to single event effect (SET) has become one of the most important reliability issues for aerospace integrated circuits. Besides the SET, integrated circuits will be affected by multiphysics such as temperature and voltage when working in space. Currently, the commonly used modeling methods are based on physical mechanisms and the double exponential pulse current. However, both methods are hard to build an accurate SET current model when various variables are considered. In this article, a novel machine learning modeling method of multiphysics SET is proposed, using intelligent algorithms to optimize the network also. With this method, we can obtain a reasonable and accurate multiphysics SET model based on neural network with single hidden layer, and there is no need to consider complex physical mechanisms. The model data is collected from TCAD simulation. Ant colony algorithm was used to optimize the initial values of the network. The RMS (root mean square error) of modeling result is less than 2%.

Comparison of single and double pulse laser-induced breakdown spectroscopy for the detection of biomolecules tagged with photon-upconversion nanoparticles

BackgroundLaser-induced breakdown spectroscopy (LIBS) is a well-recognized analytical technique used for elemental analysis. This method is gaining considerable attention also in biological applications thanks to its ability for spatial mapping and elemental imaging. The implementation of LIBS in the biomedical field is based on the detection of metals or other elements that either naturally occur in the samples or are present artificially. The artificial implementation of nanoparticle labels (Tag-LIBS) enables the use of LIBS as a readout technique for immunochemical assays. However, one of the biggest challenges for LIBS to meet immunoassay readout standards is its sensitivity. ResultsThis paper focuses on the improvement of LIBS sensitivity for the readout of nanoparticle-based immunoassays. First, the LIBS setup was optimized on photon-upconversion nanoparticle (UCNP) droplets deposited on the microtiter plate wells. Two collection optics systems were compared, with single pulse (SP) and collinear double pulse (DP) LIBS arrangements. By deploying the second laser pulse, the sensitivity was improved up to 30 times. The optimized SP and DP setups were then employed for the indirect detection of human serum albumin based on immunoassay with UCNP-based labels. Compared to our previous LIBS study, the detection limit was enhanced by two orders of magnitude, from 10 ng mL−1 to 0.29 ng mL−1. In addition, two other immunochemical methods were used for reference, based on the readout of upconversion luminescence of UCNPs and absorbance measurement with enzyme labels. Finally, the selectivity of the assay was tested and the practical potential of Tag-LIBS was demonstrated by the successful analysis of urine samples. Significance and noveltyIn this work, we improved the sensitivity of the Tag-LIBS method by combining new labels based on UCNPs with the improved collection optics and collinear DP configuration. In the instrumental setup optimization, the DP LIBS showed better sensitivity and signal-to-noise ratio than SP. The optimizations allowed the LIBS readout to surpass the sensitivity of enzyme immunoassay, approaching the qualities of upconversion luminescence readout, which is nowadays a state-of-the-art readout technique.

Study of spectral lines behaviour with a double pulse 1064–1064 nm laser-induced breakdown spectroscopy system at the direct analysis of algae on the filter

The nickel and zinc contamination of algae on a cellulose filter was studied with double pulse 1064–1064 nm laser-induced breakdown spectroscopy (LIBS). Samples of the green alga Desmodesmus subspicatus were contaminated with zinc and nickel. The surface concentrations on the filter calculated from the reference Inductively Coupled Plasma Mass Spectrometry analysis were 25 and 64 ng cm−2 for nickel and zinc respectively. The algae are resting on the filter after drying and a double adhesive tape was used to fix the sample on the microscopic glass. During optimization method a compromise of 23–30 mJ pulse energies were set for maintaining a detectable or highest signal intensity of the analyte and not destroying the filter. Best conditions for maximum analyte signal and minimum deviation between the spectral behaviour of the analyte and the compared line of Na I, K I, Mg I, Mg II, Mn I, Mn II, Ca I, Ca II, and C I was 700 ns gate delay and 0 s interpulse delay. The deviation was rather more influenced with the signal-to-noise ratio of the analyte line than the closeness of the upper-level energies of the compared lines. The filter without algae showed systematically lower electron number density and total emissivity by units of percents than the filter with algae.

Passively mode-locked Er-doped fiber laser with single and double wavelength pulses based on germanene saturable absorber

In this paper, we focus on the single crystal material germanium (Ge), which is fabricated into saturable absorbers (SAs) employing liquid phase exfoliation, and validate it with an erbium-doped fiber laser (EDFL). The Ge SA was obtained with a modulation depth of 9.8% and a saturation intensity of 11.02 MW cm−2. The single-wavelength mode-locked pulse with a minimum pulse width of 847 fs was obtained at a cavity length of 10.5 m. In addition, at a cavity length of 106 m, a dual-wavelength mode-locked phenomenon was obtained in which the central wavelengths were located at 1559.20 nm and 1561.31 nm. The experimental results show that Ge nanosheets in an EDFL provide a strong basis for the development of nonlinear optics and have a wide range of applications in the field of pulsed fiber lasers.

Using double pulse laser ablation in air to enhance the strength of laser-driven shocks

In the process of multi-pulse laser ablation, inter-pulse delay time, Δt, is known to be an important parameter for maximizing ablation efficiency as well as impulse imparted to the target. In this work, using photon Doppler velocimetry, we show that for single pairs of colinear pulses (1064 nm, 8 ns, ∼ 60 J cm-2 per pulse) in air, the peak free surface velocity of the back surface of an aluminum target (125 µm thick) is increased, by a factor of nearly 3, when Δt = 10 microseconds, compared with both pulses arriving simultaneously (Δt = 0). Fast imaging of the ablation process suggests this enhancement is due to rarefaction of the contiguous air in the passage of the leading shock produced by ablation, which then in turn allows a larger fraction of the energy of the second pulse to reach the target surface. This interpretation is strengthened by additional experiments in which the two pulses do not overlap on the target surface, but the shock strength is nevertheless enhanced. Given a fixed energy budget this work suggests a prescription for maximizing laser-driven shock strength by judicious choice of inter-pulse delay.

The effect of heat input on weld-bead geometry, mechanical, phase transformation temperature, and corrosion properties of autogenous double pulse TIG welded nitinol sheets

This research aims to analyze the welding of 1 mm thick NiTinol sheets using an autogenous double pulse tungsten inert gas (DPTIG) welding process. The effect of heat input (HI) on bead geometry, microstructure, hardness, tensile strength, phase transformation temperature (PTT), and corrosion behavior was studied. The lower (111.25 J/mm), and higher (120.14 J/mm) HI produced an average grain size of 26 μm and 36 μm, respectively. The microstructure of the fusion zone (FZ) had coarser columnar grains with intermetallic phases such as Ni3Ti, and TiO2. The grain size in the FZ increased with the increase in HI. Sample P (111.25 J/mm) showed a higher hardness of 280.54 HV and tensile strength of 566 MPa due to a higher proportion of austenite phase (99.4%), the smaller grain size of 26 µm, a larger fraction of high angle grain boundary (HAGB) of 75.8%, and higher kernel average misorientation (KAM) value of 4.93. Compared to base metal (BM), sample P (111.25 J/mm), and sample S (120.14 J/mm) exhibited a reduction in tensile strength of 19.14% and 32.29%, respectively. The decline in hardness and tensile strength was attributed to the formation of intermetallic phases, a decrease in the Ti/Ni ratio, coarser grain formation, and a decrease in HAGB fraction and KAM values. The fractured tensile samples showed a mixed mode of fracture with dimples and cleavage facets. Compared to BM, Sample Q (118.05 J/mm) exhibited lesser variation in temperature hysteresis values for austenite and martensite temperatures, with a deviation of 0.4°C and 3.1°C, respectively. All the welded samples had better corrosion behavior than the BM due to a higher Ti/Ni ratio.

An innovative pulsed current arc welding technology for armor steel: Processes, microstructure, and mechanical properties

This study presents a novel pulsed current arc welding technology, specifically pulsed current gas tungsten arc welding (PC-GTAW), single and double pulse gas metal arc welding (SP/DP-GMAW), and dual process welding (D-process). This study aims to investigate the effectiveness of these welding techniques for armor steel weldments. This research focused on investigating the welding processes, resulting microstructures, and mechanical properties of welded joints. Based on the macrography analysis, it was determined that the weldments exhibit no signs of porosity, inclusions, or inadequate penetration. This finding substantiates the optimum settings for the weldment production process. The weldment optical microstructure, fusion, and heat-affected zone were examined in the weld interface. The microstructural properties of the FZ include δ-ferrite, austenite, bainite, and acicular martensite. The HAZ has a bainite-untempered martensite microstructure. The chemical composition and variations across the weldment (base, weld and HAZ) were identified. The grain borders contained greater quantities of Cr, Ni, Mn, Si, and Mo than those of the grain cores. EBSD revealed average weld zone grain sizes of 17.7 µm, 32.6 µm, 30.8 µm, and 24.6 µm for PC-GTAW, SP-GMAW, DP-GMAW, and D-Process, respectively.Furthermore, the hardness measurements showed a progressive transition across different regions. Additionally, the D-Process-fabricated material exhibited a maximum ultimate tensile strength of 872 MPa and an elongation of 4%. The mechanical properties exhibited by this new process variant exceed those of other weldments, indicating its potential for fabricating armor steel. The impact toughness demonstrated superior performance in all the weldments. Within this context, the new use of pulsed current advanced welding methods has shown the ability to generate welded parts of exceptional quality.

Optimisation and study of a welding process for aluminium and galvanised steel based on resistance welding

In this study, taking six-series aluminium alloy and DC06 galvanised steel resistance spot welding as the object of study, the impacts of the electrode cap shape and process parameters on the joint welding performance were analysed, and the electrode cap was optimised. The optimised process parameters involved the use of spherical asymmetric electrodes and a pre-welding preheating step for zinc extrusion treatment, followed by a double pulse for welding. The optimal parameters resulted in an aluminium/steel spot welding head average pull shear failure load of 2858.7 N and aluminium/aluminium spot welding head failure force of 2436 N, reaching 117.3% of its original value. The minimum force value (2253.4 N) was greater than 92.5%, and the failure section was all from the aluminium side in parent material button failure, achieving good final results.

Targeting Transcutaneous Spinal Cord Stimulation Using a Supervised Machine Learning Approach Based on Mechanomyography.

Transcutaneous spinal cord stimulation (tSCS) provides a promising therapy option for individuals with injured spinal cords and multiple sclerosis patients with spasticity and gait deficits. Before the therapy, the examiner determines a suitable electrode position and stimulation current for a controlled application. For that, amplitude characteristics of posterior root muscle (PRM) responses in the electromyography (EMG) of the legs to double pulses are examined. This laborious procedure holds potential for simplification due to time-consuming skin preparation, sensor placement, and required expert knowledge. Here, we investigate mechanomyography (MMG) that employs accelerometers instead of EMGs to assess muscle activity. A supervised machine-learning classification approach was implemented to classify the acceleration data into no activity and muscular/reflex responses, considering the EMG responses as ground truth. The acceleration-based calibration procedure achieved a mean accuracy of up to 87% relative to the classical EMG approach as ground truth on a combined cohort of 11 healthy subjects and 11 patients. Based on this classification, the identified current amplitude for the tSCS therapy was in 85%, comparable to the EMG-based ground truth. In healthy subjects, where both therapy current and position have been identified, 91% of the outcome matched well with the EMG approach. We conclude that MMG has the potential to make the tuning of tSCS feasible in clinical practice and even in home use.

Flow Visualisation by Laser Sheet in a Smoke-Tunnel

The application of wind tunnel for visualizing flow over any bluff or streamline body plays an indispensable role in concepting various aerodynamical phenomenon such as formation of vortices, generating lift and drag, calculation of velocity vector and pressure profiles etc. Flow visualization through smoke and laser optics in a subsonic wind tunnel to capture vortex formation over airfoils, cylindrical and conical bodies is the experimental approach which has been studied and manifested elaborately in the article. Using smoke as a seeding material, the flow of the same is allowed to pass over the model which is illuminated via a double pulse laser beam to visualize the formation of vortex and capture the same for future references. The experimentation of the above models is carried out in a Honeycomb subsonic wind tunnel in the Aerodynamics Lab of Aerospace Engineering in the university. The article will cover Computational Fluid Dynamics (CFD) performed on ANSYS for the particular NACA series, Cross correlation PIV for plotting velocity vector for the captured images of the seed particles and the respective images of the entire experimental set-up. The images captured during this experiment can be later used by the aerodynamicists for optimizing aerodynamic efficiency of the experimented models depending on the vortex formation and flow pattern. The images can also be used for advance calculations required in Particle Image Velocimetry (PIV) for calculating velocity of every speed particle.

Using single and double laser pulses on the molecular Ni4@C48H36 system to design integrated nanospintronic units.

The accomplishment of long-distance spin transfer scenarios between several magnetic centers is a big challenge for building and supporting spin-logic units for developing future all-optical magnetic unit operations. Using high-level quantum chemistry theory CCSD and EOM-CCSD, we systematically study the ultrafast laser-induced spin-dynamics process on a carbon-based material, to which four magnetic centers are attached. We show that the CCSD method with the 6-31G basis set calculation is sensitive to the C-Ni bond length. The spin density distribution, which is computed using EOM-CCSD with LanL2DZ+ECP calculations, Mulliken population analysis, including spin-orbit-coupling (SOC) and a magnetic field, fulfills the requirements for achieving spin dynamics processes. Different local spin-flip and spin-transfer processes are accomplished within the subpicosecond regime. The impact of the propagation direction of the laser pulse by switching their polar and the azimuthal angles in spherical coordinates on the spin dynamics processes is analyzed. Double laser pulses with time delay δt ≥ 200 × FWHM yield in a realistic magnetic field gradient selectively a lateral resolution, which corresponds to distances smaller than the CMOS scale (2 nm in 2024) while our system size is comparable to the CMOS scale. Here Λ and V processes with two quasi-degenerate intermediate levels are used. We propose a model of an integrated spin-logic processor created from an array of individual spin-logic blocks, which are realized by four magnetic centers Ni. The findings of this study demonstrate the enormous potential of using laser-induced spin dynamics as the fundamental mechanism for future molecular magnetic technology.

Enhancement of dynamic strain range based on phase-sensitive OTDR with time-delay double probe pulses

Enhancement of dynamic strain range based on phase-sensitive OTDR with time-delay double probe pulses

Response Characteristics of a ZnO Arrester Under Nanosecond Electromagnetic Pulse

Zinc oxide arresters, a major type of overvoltage protection equipment in power systems, can suppress transient lightning overvoltage, operation overvoltage, and other types of power surges. However, the response characteristics and protection effects under nanosecond pulses, such as those in a high-altitude electromagnetic pulse conduction region, remain unclear. Therefore, the surge protection performance of arresters should be properly understood, and high-performance arresters should be developed. In this study, critical parameters, including overshoot peak voltage, residual voltage, response time, and voltammetry characteristics of a representative 10 kV ZnO arrester under nanosecond pulses, were obtained using a double exponential pulse current injection source. The overshoot peak voltage of this arrester under a nanosecond pulse is 2.19 times of lightning impulse residual voltage, and the residual voltage ratio under a nanosecond pulse is 4.31. The average response time is approximately 45 ns, and the response time is independent of the nanosecond pulse amplitude. Furthermore, an electromagnetic transient model of this type of lightning arrester is established based on the CIGRE guidelines, as well as a method to determine the key parameters. The model can simultaneously account for the response characteristics of the small current region and the conduction region of the arrester, which properly agrees with the experimental results.

Achieving excellent properties of resistance spot welded 2GPa-grade press hardened steel and galvanized DP980 steel via double-pulse

Obtaining the excellent resistance spot welding (RSW) properties of press hardened steel is a challenge due to the high strength with 2GPa-grade. In this study, the microstructure, mechanical properties of the RSW weld in 2GPa-grade PHS and galvanized DP980 steel were investigated. During the single pulse welding, the coarse columnar martensite is generated in the fusion zone (FZ). The low peak load is 13.2 kN for tensile-shear (TS) loading and 3.4 kN for cross-tension (CT) loading and the corresponding failure energy is 6.5 J and 16.7 J, respectively. The fracture mode under two loading conditions is partial thickness-partial pullout (PT-PP) mode. To enhance mechanical properties, the suitable double pulse welding was applied. Compared with that of the single pulse weld, double pulse weld has three special zones in FZ: the Re-melted FZ with columnar martensite, the recrystallization zone (RX-zone) with equiaxed martensite and the tempering zone (T-zone) with tempered columnar martensite. The peak load under the TS and CT loading is significantly improved by 39 pct and 44 pct and the failure energy for TS loading is enhanced by 38 pct and 186 pct for CT loading, respectively. The failure mode changes from the PT-PP mode to the pullout failure (PF) mode for CT loading in double pulse welds.

Atomistic-Continuum Study of an Ultrafast Melting Process Controlled by a Femtosecond Laser-Pulse Train.

In femtosecond laser fabrication, the laser-pulse train shows great promise in improving processing efficiency, quality, and precision. This research investigates the influence of pulse number, pulse interval, and pulse energy ratio on the lateral and longitudinal ultrafast melting process using an experiment and the molecular dynamics coupling two-temperature model (MD-TTM model), which incorporates temperature-dependent thermophysical parameters. The comparison of experimental and simulation results under single and double pulses proves the reliability of the MD-TTM model and indicates that as the pulse number increases, the melting threshold at the edge region of the laser spot decreases, resulting in a larger diameter of the melting region in the 2D lateral melting results. Using the same model, the lateral melting results of five pulses are simulated. Moreover, the longitudinal melting results are also predicted, and an increasing pulse number leads to a greater early-stage melting depth in the melting process. In the case of double femtosecond laser pulses, the pulse interval and pulse energy ratio also affect the early-stage melting depth, with the best enhancement observed with a 2 ps interval and a 3:7 energy ratio. However, pulse number, pulse energy ratio, and pulse interval do not affect the final melting depth with the same total energies. The findings mean that the phenomena of melting region can be flexibly manipulated through the laser-pulse train, which is expected to be applied to improve the structural precision and boundary quality.

Fast Estimation of Entropy Profiles for Lithium-Ion Batteries

The operating temperature of a lithium-ion battery (LIB) has strong effects on its electrochemical performance, safety, and lifetime. Reliable predictions of cell temperature and heat generation are required for the design and thermal management of battery systems. During the normal operation of LIBs, heat sources can be classified into irreversible heat from resistive losses such as ohmic resistance, charge-transfer overpotentials, and mass-transfer limitations; and reversible heat from entropy change . The irreversible heat generation is related to the cell's internal resistance and the applied current. The reversible heat depends on the entropy variation of electrode materials, the state of charge (SoC), and the temperature. An accurate measurement of entropy-variation will not only help to improve the battery operation under optimal thermal conditions but can also be used to diagnose the battery aging since it can reveal crystal structure changes in the electrodes [1, 2].Techniques for measuring the entropy of a battery can mainly be classified into potentiometric [3] and calorimetric methods. The potentiometric method measures the open circuit voltage (OCV) changes while the cell temperature is varied at different SoCs. This method requires a long relaxation time to obtain the OCV equilibrium state following each SoC point and temperature step. The calorimetric method [4-6] is based on measuring the heat generation during charge and discharge, and various models are applied to differentiate between and quantify the reversible and irreversible heat sources. The entropy variation with SOC is obtained via the reversible heat rate.Recent improved methods include e.g., Schmidt et al. [4] who proposed a reversible heat extraction method based on electrothermal impedance spectroscopy (ETIS) and Damay et al. [5] proposing a fast calorimetric method to obtain a continuous entropy profile. The cell surface temperature is monitored while the battery is charged and discharged continuously. A thermal balance is used to estimate the heat generation from the monitored cell temperature changes during charge and discharge. The benefit of this method can be low cost, fast and high resolution. Bedürftig et al. [6] proposed a calorimetric method named ‘Double Pulse Method’ to measure reversible heat in lithium-ion battery cells by exciting the cell with charge and discharge current pulses.Here we present a new entropy characterization method via charge and discharge cycles of a LIB at low constant C-rates using simple insulating condition. Through monitoring the variations of cell surface temperature and voltage with the state of charge, the continuous variation of entropy with the state of charge can be extracted. These results were compared to classical entropy measurements obtained through the potentiometric method as shown in Figure 1. In addition, the extracted entropy variation data is input into a LIB modelling approach, combining a P2D-electrochemical sub-model for battery operation and a 3D-finite-element sub-model for thermal behavior while battery charge and discharge. The model predictions on the cell outer surface temperature variation while charge and discharge under different C-rates are compared with the data obtained in the battery characterization tests as shown in Figure 2. Good agreements between the model predictions and tests are achieved.

Multi-pulse random fiber laser with wide tuning range in L-band based on tunable band-pass filter and electro-optic modulator

In this paper, a L-band random fiber laser (RFL) with wide tuning range based on tunable band-pass filter (TBF) and electro-optic modulator (EOM) is proposed and studied. The L-band erbium-doped fiber amplifier (L-EDFA) is added to output L-band laser, and a wavelength tunable band-pass filter is used to generate tunable wavelength output. When the pump power is increased from 50mW to 350mW, the output spectra are all chaotic multi-wavelengths. After the filter being added, a stable narrow-band single-wavelength laser can be output in the range of 1564–1618 nm. An EOM is added to introduce actively Q-switched. When the pump power is 50mW, a stable single pulse output can be observed on the oscilloscope. When the pump power is 100mW, the output pulse is double pulse. When the pump power exceeds 100mW, three pulses or four pulses phenomenon appears. The adjustable multi-pulse laser has a wide application prospect in pulse coding, secure communication and other fields.