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The laser beamline in SULF facility
摘要： In this paper, we report the recent progress on the 1 PW/0.1 Hz laser beamline of Shanghai Superintense Ultrafast Laser Facility (SULF). The SULF-1 PW laser beamline is based on the double chirped pulse ampli?cation (CPA) scheme, which can generate laser pulses of 50.8 J at 0.1 Hz after the ?nal ampli?er; the shot-to-shot energy ?uctuation of the ampli?ed pulse is as low as 1.2% (std). After compression, the pulse duration of 29.6 fs is achieved, which can support a maximal peak power of 1 PW. The contrast ratio at ?80 ps before main pulse is measured to be 2.5 × 10?11. The focused peak intensity is improved by optimizing the angular dispersion in the grating compressor. The maximal focused peak intensity can reach 2.7 × 1019 W/cm2 even with an f /26.5 off-axis parabolic mirror. The horizontal and vertical angular pointing ?uctuations in 1 h are measured to be 1.89 and 2.45 μrad, respectively. The moderate repetition rate and the good stability are desirable characteristics for laser–matter interactions. The SULF-1 PW laser beamline is now in the phase of commissioning, and preliminary experiments of particle acceleration and secondary radiation under 300–400 TW/0.1 Hz laser condition have been implemented. The progress on the experiments and the daily stable operation of the laser demonstrate the availability of the SULF-1 PW beamline.
关键词： lasers,ultrafast lasers,titanium,laser ampli?ers
更新于2025-09-23 15:21:01
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Tilted Snowplow Ponderomotive Electron Acceleration With Spatio-Temporally Shaped Ultrafast Laser Pulses
摘要： We propose a novel scheme for using the ponderomotive force of a tilted ultrafast laser pulse to accelerate electrons in free space. The tilt of the intensity envelope results from the angular dispersion of the pulse’s spectrum and slows down the interaction of the pulse with free electrons. The slower effective pulse velocity allows time for the electrons to accelerate from rest while remaining on the wave. We present both non-relativistic and relativistic analytic single-particle models in the adiabatic ponderomotive approximation, describing the process for an ideal infinite tilted pulse as well as a finite width beam. The analysis predicts the threshold intensity as a function of the pulse front tilt angle and shows that in the ideal case the output energy of the electrons is four times that of the ponderomotive potential at the capture threshold. Full-field simulations using the 2D OSIRIS 4.0 particle-in-cell code confirm the basic scheme. This tilted pulse acceleration scheme shows promise as a lab-scale method of accelerating electrons to the MeV level with good energy and angular resolution, to be used for ultrafast electron diffraction or injection into a second stage accelerator.
关键词： ponderomotive force,spatio-temporal pulse shaping,ultrafast lasers,laser electron accelerators,relativistic kinematics
更新于2025-09-23 15:19:57
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High-flux ultrafast extreme-ultraviolet photoemission spectroscopy at 18.4?MHz pulse repetition rate
摘要： Laser-dressed photoelectron spectroscopy, employing extreme-ultraviolet attosecond pulses obtained by femtosecond-laser-driven high-order harmonic generation, grants access to atomic-scale electron dynamics. Limited by space charge effects determining the admissible number of photoelectrons ejected during each laser pulse, multidimensional (i.e. spatially or angle-resolved) attosecond photoelectron spectroscopy of solids and nanostructures requires high-photon-energy, broadband high harmonic sources operating at high repetition rates. Here, we present a high-conversion-efficiency, 18.4-MHz-repetition-rate cavity-enhanced high harmonic source emitting 5 × 10^5 photons per pulse in the 25-to-60-eV range, releasing 1 × 10^10 photoelectrons per second from a 10-μm-diameter spot on tungsten, at space charge distortions of only a few tens of meV. Broadband, time-of-flight photoelectron detection with nearly 100% temporal duty cycle evidences a count rate improvement between two and three orders of magnitude over state-of-the-art attosecond photoelectron spectroscopy experiments under identical space charge conditions. The measurement time reduction and the photon energy scalability render this technology viable for next-generation, high-repetition-rate, multidimensional attosecond metrology.
关键词： attosecond science,photoelectron spectroscopy,high-harmonic generation,cavity enhancement,ultrafast lasers
更新于2025-09-19 17:15:36
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[OSA CLEO: Science and Innovations - San Jose, California (2014..-..)] CLEO: 2014 - Arbitrary Carrier-Envelope Phase Control in a 10 kHz, mJ-Class Amplifier
摘要： The carrier-envelope phase of every single shot emitted by a 10 kHz, mJ-class amplifier is measured with a fast spectrometer. A novel high-speed actuator allows arbitrary phase control, with closed-loop integrated phase noise on seed oscillator level (98 mrad, 5.10^5 shots, 50 s).
关键词： Laser amplifiers,Carrier-envelope phase,Ultrafast lasers,Phase control,Amplifier
更新于2025-09-19 17:15:36
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Recent progress in ultrafast lasers based on 2D materials as a saturable absorber
摘要： Two-dimensional (2D) materials are crystals with one to a few layers of atoms and are being used in many fields such as optical modulator, photodetector, optical switch, and ultrafast lasers. Their exceptional optoelectronic and nonlinear optical properties make them as a suitable saturable absorber for laser cavities. This review focuses on the recent progress in ultrafast laser use 2D materials as a saturable absorber. 2D materials traditionally include graphene, topological insulators, transition metal dichalcogenides, as well as new materials such as black phosphorus, bismuthene, antimonene, and MXene. Material characteristics, fabrication techniques, and nonlinear properties are also introduced. Finally, future perspectives of ultrafast lasers based on 2D materials are also addressed.
关键词： saturable absorber,MXene,antimonene,bismuthene,graphene,ultrafast lasers,transition metal dichalcogenides,black phosphorus,2D materials,topological insulators
更新于2025-09-19 17:13:59
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Advances in Ultrafast Optics || 1. Ultrafast ultrahigh-intensity laser pulses
摘要： Generation of high intensity laser pulses has been regarded as one of the most important research topics since the invention of lasers. High intensity lasers are normally constructed using the master oscillator power amplifier (MOPA) configuration to boost the energy of short laser pulses. This configuration has been used in various locations such as the Shenguang facilities in China and the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory (LLNL) in the USA; the latter is currently the largest laser facility in the world. This type of giant laser facility is usually employed for high-cost and large-scale scientific projects involving complex technology and only a few countries can perform this type of laser research. Because of the low repetition rate and long pulse duration of the achieved laser pulses, these laser facilities are not suitable for large-scale applied research. Furthermore, the output laser intensity is limited. For example NIF, constructed in 2009, includes 192 ultraviolet (UV) beams with the total energy up to 1.8 megajoules (MJ, 106 J). However, the peak power is only approximately 500 terawatts (TW; 1012 W) [1] because the pulse duration is at the nanosecond (ns; 10?9 s) level; the separation time between two pulses is as long as a few hours. At the other end of the scale, several research institutes have developed tabletop laser systems within regular-scale labs through the amplification of ultrashort-pulse lasers at the femtosecond (fs; 10?15 s) level. These lasers have peak powers at the petawatt (PW; 1015 W) level [2–4], a repetition rate of 1 hertz (Hz) [5], and a focus intensity reaching 1022 W/cm2 [6]. As a result of the 1991 discovery of the Kerr-lens mode-locking (KLM) phenomenon by the Sibbett group in the UK [7], along with the development of chirped pulse amplification (CPA) technology by the US-based Mourou group in 1985 [8], and research on ultrashort pulses, ultrahigh-intensity lasers have been advancing at an unprecedented pace since the late 1980s. New scientific records associated with significant breakthroughs have been made on a continuous basis. Ultrashort-pulse laser research has developed in two explorative directions. One path of development targets extremely short pulse duration promoted by mode-locking technology. Currently, laser pulse duration can reach the few-cycle level; in addition, attosecond (as; 10?18 s) laser pulses can be achieved using new physical mechanisms [9–11]. The second research trend is the ongoing extension of the laser peak power limit. An increasing number of femtosecond ultrahigh-intensity laser facilities with peak powers at the terawatt or even petawatt level have been developed [2–5], serving as powerful tools for in-depth research on ultrafast, ultrahigh-intensity laser pulses. Ultrashort pulses and ultrahigh-intensity laser technology are not only extensively employed in the fields of micromanufacturing [12–14] and medicine [15, 16] but have also been successfully and prominently implemented in various research areas, such as the exploration of atomic and molecular motion patterns [17, 18], laboratory simulations in astrophysics [19], and precision spectroscopy [20]. These applications have facilitated the emergence of many new subfields and groundbreaking scientific achievements. One of the two most representative events was the award of the 1999 Nobel Prize in Chemistry to the American researcher, Prof. A. H. Zewail. This prize was awarded for work on chemical kinetics using femtosecond laser pulses. The second representative achievement was the joint sharing of one half of the 2005 Nobel Prize in Physics by Profs. J. L. Hall and T. W. H?nsch; this prize was awarded for their achievements regarding the femtosecond laser frequency comb technique. With state-of-the-art features and innovative applications, ultrashort pulses, ultrahigh-intensity lasers have become crucial tools in the field of optical physics. Therefore, this chapter will first briefly review the essential technology and associated progress in research.
关键词： ultrahigh-intensity lasers,femtosecond lasers,laser technology,Kerr-lens mode-locking,petawatt lasers,optical physics,chirped pulse amplification,ultrafast lasers
更新于2025-09-16 10:30:52
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All-Fiber Bidirectional Mode-Locked Ultrafast Fiber Laser at 2? <i>μ</i> m
摘要： In this paper, we demonstrated an all-?ber bidirectional ultrafast thulium-doped ?ber laser at 2 μm with a single-wall carbon nanotube presented as saturable absorber. We successfully obtained bidirectional mode-locking operations with pulse repetition frequency adjustable from 35 to 122 MHz by shortening the cavity length. Meanwhile, with the reduction of the intracavity dispersion, the number of Kelly sidebands was signi?cantly decreased and the output energy was more concentrated on the soliton pulse. Besides, by manipulating the pump power and polarization controller, the two results of bidirectional mode-locked pulses with the same repetition frequency and differential repetition frequency were observed. We found that the repetition rate difference between the clockwise and counterclockwise pulse trains was adjustable by changing the pump power or controlling the intracavity polarization. When the pulse repetition frequency was 35 MHz and 122 MHz, the adjustment range of repetition rate difference was 764–922 Hz and 540–2000 Hz, respectively. It is believed that this novel laser source can support free-running dual optical comb spectroscopy to detect important air gases like H2O or CO2 in the future.
关键词： infrared and far-infrared lasers,thulium-doped ?ber,?ber optics and oscillators,Ultrafast lasers
更新于2025-09-16 10:30:52
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Visualizing the a??Invisiblea?? Soliton Pulsation in an Ultrafast Laser
摘要： Pulsation is a universal phenomenon that exists in diverse fields. For nonlinear optics, the soliton pulsating behavior can be meaningful for fundamental physics and industrial purpose owing to its fruitful nonlinear dynamics and the possible detrimental effect of instability (or even route to chaos) during pulsating process. Herein, a novel type of soliton pulsation in an ultrafast laser is unveiled. The pulsating behavior features that the soliton experiences periodic peak power variation but with almost invariable pulse energy. This phenomenon is denoted as “invisible soliton pulsation” when referring to the routine diagnostic methods. However, the invisible soliton pulsation can be distinguished by recording the shot-to-shot spectra with real-time spectroscopy technique. It is found that the appearance of the invisible soliton pulsation is sensitive to the pump power level. Moreover, the phenomenon of invisible soliton pulsation is further revealed by numerical simulations. These findings can shed new insights into the complex nonlinear behavior of solitons in dissipative optical systems, and also enrich the performance diagnostic of ultrafast lasers for practical applications.
关键词： soliton dynamics,ultrafast lasers,soliton pulsation
更新于2025-09-16 10:30:52
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High-resolution material structuring using ultrafast laser non-diffractive beams
摘要： Scales in the 100 nm range represent a generic cornerstone for laser material processing, enabling novel size-dependent functions on surfaces and in the bulk and thus a new range of technological applications. On these scales, the processed material acquires optical, transport or contact properties that do not only rely on local e?ects on singular topographic features but involve increasingly collective behaviors. Rapid access to sub-100 nm features with intense coherent light represents nevertheless a challenge in laser structuring in view of the optical di?raction limit. Ultrafast non-di?ractive beams with controllable time envelopes can overcome this limit and achieve super-resolved processing, a prerequisite for the next generation of ?exible and precise material processing tools. They show a remarkable capacity of structuring transparent materials with high degree of accuracy and exceptional aspect ratio. This capacity relies on triggering fast hydrodynamic and material fracture e?ects with characteristic spatial scales in the nm range. Reviewing the present achievements and technical potential, we discuss from a dynamic viewpoint the physical mechanisms enabling structural features beyond di?raction limit achieved using ultrafast Bessel beams and indicate applications of high technical relevance.
关键词： nanotechnology,non-di?ractive beams,Ultrafast lasers,laser processing
更新于2025-09-12 10:27:22
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Novel strategy for ultrafast pulsed laser micromachining of rotational symmetric metallic parts
摘要： Ultra-fast lasers have already been used to machine rotational symmetric metallic parts for several years but did not prevail against much cheaper fiber lasers. The limiting factor up to now is the dynamics of the rotary and linear axes, that are used to move the part underneath the stationary laser beam. Although the quality of the surface machined with ultrafast pulsed laser radiation is better than that machined with fiber laser radiation, an overall economic consideration mostly did not justify the utilization of ultrafast pulse lasers for this kind of application. Therefore, new and innovative concepts are needed to exploit the potential of ultrafast pulse lasers, in particular high repetition rate and the steadily increasing average power. The realization that will be presented uses a high-end galvanometric scanner to move the laser beam at speeds of several ten meters per second across the constantly rotating part. The most important part is the synchronization of the laser, the scanner and the axes.
关键词： efficiency,ultrafast lasers,laser micro machining,synchronization,galvanometric scanner
更新于2025-09-12 10:27:22