Physics and Applications of Superintense and Ultrafast Lasers

Significance The appearance and rapid development of superintense and ultrafast laser have opened up many frontier areas in subjects such as atomic and molecular physics, strong field physics, and plasma physics, and superintense and ultrafast laser itself has become a powerful tool in numerous applications. The extreme nonlinear interaction between superintense and ultrafast lasers and atomic or molecular systems induces strong field ionization, attosecond radiation, femtosecond laser filamentation, and air lasing. Attosecond physics may develop new technological means for the study of electronic dynamics in complex systems that are relevant to physics, chemistry, biomedicine and other subjects. Laser filamentation and air lasing have brought new opportunities for applications based on laser plasma associated radiation, laser atmospheric remote sensing and material analysis, weather modification, and laser material processing. With the increase of laser intensity, physical processes enter the relativistic plasma regime, where many applications have been developed in laser - driven particle acceleration, laser - driven high - energy radiation sources, ultrafast electronic dynamics, laser nuclear physics, and laboratory astrophysics. Laser - driven ultra - high - gradient particle accelerators and high - energy ultrafast radiation are advantageous in producing compact particle and radiation sources with ultra - high peak brightness and ultrafast time duration, thus are unique in several key applications. Especially, laser - driven plasma wakefield acceleration is promising in generating high energy electrons to develop table - top X - ray free electron lasers. On the other hand, laser - driven ion acceleration is believed to bring new opportunities in tumor therapy, proton imaging, and fast ignition fusion. As the laser intensity further increases, the extreme strong field effect gradually becomes apparent and it enters the strong field quantum electrodynamics (QED) regime, resulting in a series of new phenomena such as quantum gamma radiation, generation of electron - positron pairs, vacuum polarization, QED cascades and so on. These studies would extend boundaries of laser - matter interaction. New properties such as spin and orbital angular momentum also emerge as new degree of freedom in laser - plasma interaction. The interaction between superintense laser and plasma is an important means of generating radiation at different wavelengths. The study of terahertz radiation sources driven by superintense lasers can further improve the laser energy conversion efficiency. The free electron and quasi - particle radiation driven by superintense laser is of great significance for the development of miniaturized and integrated new coherent light sources and terahertz - driven electron sources. Ultrafast lasers provide processing accuracy beyond the limits of optical diffraction, enabling high - quality micro - nano processing. In addition, micro - nano lasers are important for promoting the miniaturization and integration of optoelectronic devices. Progress This review first introduces nonlinear atomic and molecular physics driven by ultrafast lasers, followed by superintense lasers and relativistic plasma physics at higher intensities, and finally reviews the cross - disciplinary frontier applications of superintense ultrafast laser. This review will highlight the progresses and achievements made by the State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, in the long - term dedicated research on superintense ultrafast laser physics and its frontier applications. The laboratory has made significant progresses in the generation and control of high - order harmonics and single attosecond pulse, high brightness high - order harmonic coherent light sources, water window or keV high - order harmonic generation driven by mid - infrared wavelength lasers, and high - order harmonic generation in condensed matter. Important progresses in femtosecond laser filamentation measurement and control, femtosecond laser weather modification, and air lasing are also elaborated. In recent years, the laboratory has developed stable and usable high - quality laser - driven electron sources. The laser energy conversion efficiency and beam quality of high - energy and ultrafast radiation sources have also been improved. Compact free electron laser in the extreme ultraviolet band has been demonstrated based on laser - driven wakefield electrons for the first time in the world. Laser - driven ion acceleration has seen rapid development in the past decades, where new acceleration mechanisms have been proposed, and the laser energy conversion efficiency and the cut- off energies of protons are now sitting in the first class in the world. In the strong field QED regime, the radiation- reaction trapping of electrons and the upper limit of laser intensity caused by non- ideal vacuum are discovered. The exploits of vortex laser on particle acceleration and secondary radiations are developed in the laboratory. The laboratory has also successfully generated positrons using superintense laser and proposed new schemes for the detection of dark matter particles such as axion. Significant progress in the generation of intense terahertz radiation has been made. The quasi- particle radiation amplification mechanism and electron acceleration driving the terahertz radiation have been explored, which provides a unique platform for surface light sources and applications. In addition, a number of research achievements have been made in ultrafast laser micro- nano processing and micro- nano lasers. Conclusions and Prospects The development and application of superintense ultrafast laser technology have significant impacts on disciplines such as physics, chemistry, and biology. It is a highly competitive area of research worldwide. The progresses highlighted in this review will further guide the development of advanced laser technology and light sources, compact particle accelerators, and extend our knowledge on light- matter interaction. It is now an important stage to bring the research in laboratories to real world applications, where key aspects of the interaction should be controllable and the whole system must be stable or even cost efficient. On the other hand, the extreme field provided by 10-100 PW lasers shows unparalleled capacities in fundamental research, such as strong field QED, high energy density physics or even dark matter search. It relies on joint efforts among multiple disciplines such as plasma physics, theoretical physics, particle and nuclear physics and so on.