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Stable and compact nanosecond pulse seed source with diode laser driven by a high-speed circuit and a temperature control circuit
摘要： We demonstrated a nanosecond pulse seed source with a diode laser (DL) of 1550 nm A short pulse generator and a short pulse driver came to form a high-speed circuit that drove the seed source. A temperature control circuit was employed to control the stability of the laser pulses. The experimental results provided that continuously adjustable 5 kHz to 25 MHz repetition frequency and 3.5 ns to 51 ns pulse duration were acquired. The ?ne tuning of pulse duration of seed signals was realized by adjusting the current of the laser in its operating current range. Stability of the output power over two hours was 0.13% at repetition frequency of 25 MHz and pulse duration of 3.5 ns, respectively.
关键词： Short pulse generator,Temperature control,Short pulse driver,Pulse seed source,Nanosecond pulse
更新于2025-11-28 14:24:03
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25 nJ, 634 ps and 1 MHz all-fiber passively mode-locked fiber laser based on a GaAs saturable absorber
摘要： We demonstrate an all-fiber passively mode-locked Tm-Ho co-doped fiber laser based on a GaAs saturable absorber (SA) fiber laser at 1875.2 nm. With a 10% output coupler, the fiber laser outputs 1.13 MHz, 634 ps and 25 nJ pulses at 1875.2 nm with a 3 dB-bandwidth of 18.4 nm. The Q-switched mode-locking (QML), the mode-locking at fundamental repetition rate (FRR) and the mode-locking at second harmonic of repetition rate (SHRR) are also observed with the increase of the pump power. The main reason of the SHRR is soliton pulse energy quantization effect.
关键词： Low repetition rate,Mode-locked fiber laser,Soliton pulse,Nanosecond pulse,Soliton pulse energy quantization effect
更新于2025-11-28 14:24:03
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Keyhole cutting of carbon fiber reinforced polymer using a long-duration nanosecond pulse laser
摘要： The machining performance of a high-energy nanosecond pulse laser with a near-infrared wavelength is investigated for carbon fiber-reinforced polymer (CFRP) with two different fiber arrangements. This research work demonstrates for the first time that a keyhole mode cutting can be achieved for CFRP materials using a high-energy nanosecond pulse laser of a Long Pulse mode (120 ns). Specifically, it is shown that the short-duration Q-Switch mode (8 ns) results in ineffective material removal for CFRP, despite much higher peak laser power intensity than the Long Pulse mode. In Long Pulse mode, multi-pass straight line and contour cutting experiments are further performed to investigate the effect of laser processing parameters and resultant machined surface integrity. Plasma absorption effects using both pulse modes are discussed. The results show that a 2.2 mm thick cross-ply CFRP panel can be cut through using as few as 6 laser passes, and a high-quality machined surface can be produced with a limited heat-affected zone and minimal fiber pull-out using Argon assist gas. The successful outcomes from this work provide the key to enable efficient CFRP laser machining using high-energy nanosecond pulse lasers, and offer insight into the unique energy absorption mechanisms for CFRP laser machining.
关键词： Laser cutting,Keyhole,Long pulse,Nanosecond pulse laser,Carbon fiber reinforced polymer
更新于2025-11-21 11:08:12
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A Compact Series-Connected SiC MOSFETs Module and Its Application in High Voltage Nanosecond Pulse Generator
摘要： Nanosecond pulse discharge plasma has many prospects in industrial applications, and high voltage repetitive nanosecond pulse generators with compact design and light weight have become one of the key issues limiting its development in some applications. This paper presents a high voltage series-connected SiC MOSFETs module which can be served as the main switch in a repetitive high voltage nanosecond pulse generator. This kind of series-connected MOSFETs module with only single external gate driver requiring very few components is very suitable for compact assembly. By analyzing the working principle, three topologies of series-connected MOSFETs module are proposed. The switching behaviors of the three different topologies with four SiC MOSFETs series-connected are compared experimentally. The variation of switching characteristics of series-connection SiC MOSFETs module with different numbers of devices are investigated. The layout is also optimized to shorten pulse front time and improve output pulse quality. Furthermore, a 10 kV SiC MOSFETs module with a turn-on transition time ~10 ns is developed. The double pulse test result demonstrates excellent switching performances. Finally, a compact and high voltage pulse generator composed of three 10 kV SiC MOSFETs module is tailored, with a typical rise time ~40 ns and peak voltage of ~30 kV.
关键词： high voltage nanosecond pulse generator,series-connection,SiC MOSFET
更新于2025-09-23 15:22:29
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Two-micron all-fiberized passively mode-locked fiber lasers with high-energy nanosecond pulse
摘要： We report on mode-locked thulium-doped ?ber lasers with high-energy nanosecond pulses, relying on the transmission in a semiconductor saturable absorber (SESA) and a carbon nanotube (CNTs-PVA) ?lm separately. A section of an SMF–MMF–SMF structure multimode interferometer with a transmission peak wavelength of ～2003 nm was used as a wavelength selector to ?x the laser wavelength. When the SESA acted as a saturable absorber (SA), the mode-locked ?ber laser had a maximum output power of ～461 mW with a pulse energy of ～0.14 μJ and a pulse duration of ～9.14 ns. In a CNT-?lm-based mode-locked ?ber laser, stable mode-locked pulses with the maximum output power of ～46 mW, pulse energy of ～26.8 nJ and pulse duration of ～9.3 ns were obtained. To the best of our knowledge, our experiments demonstrated the ?rst 2 μm region ‘real’ SA-based dissipative soliton resonance with the highest mode-locked pulse energy from a ‘real’ SA-based all-?berized resonator.
关键词： high pulse energy,nanosecond pulse,Tm-doped ?ber laser,mode-locking
更新于2025-09-23 15:21:01
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SBS pulse compression using bulk fused silica by diode-pumped solid-state lasers at 1??kHz repetition rate
摘要： This study is focused on constructing a highly stable diode-pumped solid-state laser system by conducting experiments on high-repetition-rate SBS pulse compression using bulk fused silica. A multi-rod serial-connection structure is adopted for SBS expriments by comparing K8 glass and fused silica medium at a 10 Hz repetition rate. The optimized structure is obtained according to variation of the pump power density. Based on the optimized structure, fused silica-based SBS pulse compression is carried out in the range of 100–1000 Hz and the parameter performance of laser system after compression is also evaluated by comparing a HT270 liquid medium. Experimental results indicate that the energy e?ciency of fused silica-based SBS is improved by approximately 40% compared with that of K8 glass. Further, the energy relative standard deviation of fused silica-based SBS is reduced by approximately 88% compared with HT270 medium, indicating that bulk fused silica is advantageous for high-repetition-rate SBS pulse compression because of its un-?uidity, high thermal conductivity and power-load ability. In addition, a 1 kHz highly-stable sub-nanosecond compressed pulse is achieved using bulk fused silica medium at a pump energy of 50 mJ. Furthermore, the SBS energy e?ciency can be further improved by increasing the input energy.
关键词： Pulse compression,High repetition rate,Solid-state lasers,Sub-nanosecond pulse,Stimulated Brillouin scattering (SBS)
更新于2025-09-23 15:21:01
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A digital controlled pulse generator for a novel tumor therapy combining irreversible electroporation with nanosecond pulse stimulation
摘要： The irreversible electroporation with microsecond electric pulses is a new ablation technique adopted in the tumor therapy worldwide. On the other hand, the nsPEF (nanosecond pulsed electric field) has been proved to provide a means to induce immunogenic cell death and elicits antitumor immunity, which is under intensive in-vitro and in-vivo studies and in clinical trials. Normally, one needs two different types of electric pulse generators for producing the pulses in the ranges of nanosecond and microsecond, respectively. In order to realize these two types of tumor treatments in complementary and optimize electrical pulse parameters, we have developed a compact high-voltage pulse generator with a wide pulse width tuning range, based on a capacitor discharging configuration digitally controlled by a silicon carbide MOSFET switching array through a pair of optic-coupler drivers. The developed digital pulse generator is capable of adjusting: pulse width over 100ns-100μs, voltage over 0-2kV and repetition rate up to 1.2 kHz. The pulse generator is designed in simulation, implemented and verified in experiments. The pulse generator is shown to deliver a complementary treatment on Murine melanoma B16 cell lines, i.e. triggering the cell early apoptosis under the 300ns pulse stimulation while a complete killing under the 100ns pulses. The pulse generator is further demonstrated to induce antitumor immunity in a preliminary in vivo study on the mice model.
关键词： apoptosis,Silicon Carbide MOSFET array,irreversible electroporation,nanosecond pulse stimulation
更新于2025-09-23 15:21:01
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Slab RF-discharge carbon dioxide laser with active mode-locking
摘要： Mode-locking with an acousto-optic modulator was for the first time demonstrated for a repetitively pulsed (150 Hz) slab RF discharge CO2 laser. The mode-locked CO2 laser emitted trains of 5.5 ns pulses following with 27.25 MHz repetition rate. Mode-locking also affected the laser pulses envelope in respect to free-runing mode. The numerical estimation of the laser system scalability indicated an opportunity to develop a very compact CO2 laser emitting sub-nanosecond pulses.
关键词： slab design,mode-locking,RF discharge,CO2 laser,nanosecond pulse
更新于2025-09-23 15:19:57
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Imitating the effect of amplified spontaneous emission pedestal at relativistically intense laser interaction with nanostructured solid targets
摘要： We investigated the effect of focusing sub-nanosecond laser radiation with varied fluence onto the surface of different flat and nanostructured targets utilized in ultra-high intensity laser-plasma experiments. Thus, we modeled the action of the prepulse, referred to as an amplified spontaneous emission pedestal, typically present for a relativistic (with peak intensity over 1018 W cm?2) laser pulse with naturally limited contrast. The suppressed melting threshold was detected for the sub-wavelength scale structured material. Local melting leading to distortion of initial structures was detected at a fluence of ~0.2 J cm?2 and below, or 3–5 times lower compared to the flat substrate melting threshold. It is also demonstrated that the threshold lowering is dependent on the production method of the structures, which may be attributed to increased absorption and suppressed heat transfer into the bulk.
关键词： high intensity laser interaction,amplified spontaneous emission pedestal,laser melting,sub-nanosecond pulse,nanostructures
更新于2025-09-19 17:13:59
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Effect of laser texturing on the performance of ultra-hard single-point cutting tools
摘要： This paper investigates the cutting performance and anti-adhesive properties of textured single-point polycrystalline diamond (PCD) cutting tools in machining Aluminium 6082 alloys. The micro/nano textures were first milled using a fibre laser (1064-nm wavelength) at different power intensities, feed speeds and pulse durations, and finally characterised using scanning electron microscopy, white light interferometry and energy dispersive X-ray spectroscopy. The effect of different textures on the cutting performance was investigated in turning tests under dry cutting conditions. The test was stopped at regular lengths of cut to allow analysis of height of adhesion through 3D white light interferometry. The data processing of the cutting forces and the microscopical characterisation of the tested cutting tools enabled the evaluation of the effects of texture design, friction coefficient and adhesive properties. The results indicated that feed force in tools with grooves perpendicular to the chip flow direction (CFD) was more stable (20–40 N) than the benchmark (6–41 N). Similarly, the thrust force for tools with grooves parallel to CFD and grooves perpendicular to CFD showed a homogeneous trend fluctuating between 60 and 75 N as compared with the benchmark (ranging between 73 and 90 N). For texture depth in the order of 260 nm and post process roughness in the order of tens of nanometers, a reduction of average friction coefficient (0.28 ± 0.14) was reported when using lasered inserts with grooves parallel to the chip flow direction compared with the benchmark tools (0.34 ± 0.26) corroborated by reduced stiction of workpiece material on the rake face. In machining via textured tools with grooves perpendicular to CFD, the cutting forces were reduced by 23%, and the surface quality of the machined workpiece was improved by 11.8%, making this geometry the preferred choice for finishing applications. Using grooves parallel to CFD reduced the cutting forces by 11.76%, adhesion by 59.36% and friction coefficient by 14.28%; however, it increased the surface roughness of the machined workpiece, making this geometry suitable for roughing operations. For the first time, laser manufacturing is proposed as a flexible technique to functionalise the geometrical and wear properties of PCD cutting tools to the specific applications (i.e. roughing, finishing) as opposed to the standard industrial approach to use microstructurally different PCDs (i.e. grain size and binder %) based on the type of operation.
关键词： Adhesion,Dry cutting,Nanosecond pulse,Laser milling,Polycrystalline diamond insert,Laser surface texturing,Cutting forces
更新于2025-09-16 10:30:52