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Quasi single-shot two-pulse tilted pulse front autocorrelator coupled with spatial chirp and spectral divergence monitor for ultrashort pulsed laser beams
摘要： Simultaneous single-shot unambiguous detection and measurement of pulse front tilt, spatial chirp, spectral divergence and pulse width has been carried out using two-pulse tilted pulse-front autocorrelator (TP-TPFAC) coupled with spectral interferometry using small part of laser beam intercepted from Mach Zehnder delay unit of TP-TPFAC generating two delayed and spatially inverted pulses. Error in estimation of rotation angle of autocorrelation (AC) trace due to accidental improper positioning of CCD detector is avoided by measuring angle between AC traces corresponding to two delayed and spatially inverted pulses. Likewise, accuracy in estimation of spatial chirp is improved by using spatially resolved spectral trace of two spatially inverted pulses, as errors due to accidental improper positioning of either grating of spectrograph or CCD detector are avoided. Sensitivities and accuracies of the two methods are compared in different experimental situations. Estimated pulse parameters are found in close accordance with respective theoretical values.
关键词： Chirped pulse amplification,Ultrashort laser pulses,High energy high power lasers
更新于2025-09-19 17:13:59
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High Energy and Short Pulse Lasers || Phase Manipulation of Ultrashort Soft X-Ray Pulses by Reflective Gratings
摘要： In this chapter, we discuss the use of reflective diffraction gratings to manipulate the phase of ultrashort pulses in the extreme ultraviolet (XUV) and soft X-ray spectral regions. Gratings may be used to condition the spectral phase of ultrashort pulses, e.g., to compensate for the pulse chirp and compress the pulse, similarly to what is routinely realized for visible and infrared pulses. The chirped pulse amplification technique has been already proposed for soft X-ray free-electron laser radiation; however, it requires the use of a compressor to compensate for the pulse chirp and get closer to the Fourier limit. There are fundamental differences when operating the gratings at wavelengths shorter than ≈40 nm on a broad band: (a) the gratings are operated at grazing incidence; therefore, the optical design has to be consequently tailored to this peculiar geometry; (b) the grating efficiency is definitely lower; therefore, the number of diffractions has to be limited to two. We discuss the different configurations that can be applied to the realization of a grating stretcher/compressor.
关键词： extreme ultraviolet,soft X-ray optics,ultrafast optics,diffraction gratings,chirped pulse amplification
更新于2025-09-16 10:30:52
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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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Tapered erbium-doped fibre laser system delivering 10 MW of peak power
摘要： We consider a fibre laser system generating ~10-mJ, ~500-fs pulses with a peak power of ~10 MW at a repetition rate of 100 kHz and emission wavelength of 1.56 mm. The system is based on a master oscillator – power amplifier configuration. The amplifier ensures chirped-pulse amplification. The pulses are then compressed by a dispersive grating compressor. The output amplifier stage is based on a specially designed tapered large mode area erbium-doped fibre for suppressing nonlinear effects. The experimental data agree with numerical simulation results for the stretcher, amplifier and compressor. The stretcher and amplifier have been simulated using a generalised nonlinear Schr?dinger equation. In addition, numerical simulation results suggest that optimising the stretcher and compressor will potentially allow the peak power of the system to be scaled up to ~30 MW.
关键词： erbium-doped fibre amplifiers,tapered fibre,dispersive grating compressor,high peak power fibre laser systems,chirped-pulse amplification
更新于2025-09-12 10:27:22
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Frequency modulation, amplification and compression of microwave pulses in a system with helically corrugated waveguides as a dispersive elements
摘要： We consider the possible implementations of the Chirped Pulse Amplification (CPA) technique widely used in optics for the microwave frequency band. We propose using helically-corrugated waveguides for pulse stretching and compressing as their dispersion properties strongly depend on geometrical parameters. For stretched pulse amplification, a helical-waveguide gyro-TWT can be used as a broadband amplifier. Simulations with parameters of the experimentally realized 30 GHz gyro-TWT show that for a 300 W, 200 ps incident pulse, amplification up to 6 MW can be achieved in this system, while in the linear regime of the same gyro-TWT the output power is only about 250 kW.
关键词： microwave pulses,gyro-TWT,Chirped Pulse Amplification,helically corrugated waveguides
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Numerical Investigation of Broadband OPCPA Configurations for Direct Amplification of TW-Level, Two-Cycle Pulses
摘要： Generation of intense, isolated attosecond pulses is the main motivation for the development of laser systems which are producing few-cycle, TW-level pulses. The ELI-ALPS Single Cycle Laser (SYLOS) aims to provide 20 TW single cycle pulses at 1 kHz repetition rate. Due to the requirements for stability and high average power the most promising approach for generating mJ-level, few-cycle pulses is noncollinear optical parametric chirped pulse amplification (NOPCPA). BBO and LBO are the two most favoured nonlinear materials in the visible and near-infrared spectral range, due to their broad gain bandwidth and high damage threshold. It was demonstrated that BBO and LBO can support 5.5 fs and 7 fs pulse durations respectively when 450 nm and 515 nm pumping was used. Even shorter, sub-5 fs pulse durations can be achieved by utilizing two-color pumping, that is, the second- and third-harmonic of a Nd:YAG pump laser in subsequent amplifier stages. The latter solution is the most promising, however at 1 kHz repetition rate there is a risk of optics degradation due to high average power UV light. In this work, two alternative solutions were examined numerically for few-cycle pulse amplification. In the first one, single LBO crystal is used in a phase-matching configuration when the gain bandwidth supports 5 fs pulse duration. In the other solution, spectral multiplexing was utilized in a so-called BBO-sandwich configuration. The principle of the BBO-sandwich is that two thin BBO crystals packed close to each other with slightly different phase-matching angles, but the non-collinear angle between the signal and pump beams is the same in both crystals. As a result, a broader gain bandwidth can be achieved which can support 5 fs pulse duration. These broadband phase-matching configurations were numerically examined using an advanced 3D, OPCPA modelling software. The results of these simulations were well applicable either to rule out or to confirm certain configurations during the experimental development of ELI-ALPS SYLOS laser system. In most cases, the predicted total bandwidths were matched well with the experimental results, even when the spectrum shapes showed difference due to the model approximations. Numerical simulations predicts that the amplified spectrum supports 5 fs Fourier-limited duration and the spectral phase does not contain any fast oscillations thus the pulses are compressible to 5.5 fs. The output pulse energy is 50 mJ before pulse compression and the calculated Strehl-ratio is 0.77. The theoretical findings are also proved by the experimental results, which indicates that these phase-matching configuration are viable candidates for the production of TW-level, few-cycle pulses.
关键词： TW-level pulses,few-cycle pulses,broadband OPCPA,noncollinear optical parametric chirped pulse amplification,LBO,BBO
更新于2025-09-12 10:27:22
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112-μJ 180-fs pulses at 1-kHz repetition rate from Yb-doped laser based on strictly all-fiber CPA structure
摘要： In this paper, we reported an Yb-doped, femtosecond, chirped pulse amplification laser based on strictly all-fiber structure. It operated at a low repetition rate of 1 kHz and adopted the synchronously pumping technology to suppress ASE and heat accumulation. A chirped fiber Bragg grating providing adjustable dispersion is used as the pulse stretcher. High order dispersion induced by fiber, grating pair in the system was compensated accurately. Laser pulse with duration of 180 fs and energy of 112 μJ has been obtained. In addition, it has a high long-term stability of energy and a good beam quality, corresponding to energy fluctuation of 0.62% in an hour and M2 factor of 1.15, respectively.
关键词： femtosecond fiber laser,high energy,Chirped pulse amplification,synchronously pumping technology
更新于2025-09-11 14:15:04
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Half of Nobel Prize in Physics honors the inventors of chirped pulse amplification
摘要： The laureates circumvented an intrinsic limitation in laser technology to develop an amplification protocol now found in nearly every high-power, ultrafast system.
关键词： Nobel Prize,Physics,laser technology,chirped pulse amplification
更新于2025-09-04 15:30:14