Recently, the State Key Laboratory of Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Xu Zhizhan, Li Ruxin and Liu Jiansheng made great progress in the research of the new concept of miniaturized free electron laser driven by ultra-short ultra-short laser. A miniature and instantaneous State undulator program. Researchers use the ultra-short and ultra-short laser to interact with the metal wire to produce a high-energy electron beam while utilizing the charge separation effect to construct a miniature and transient electronic undulator. Based on this new undulator scheme, the nonlinearity Magnified strong THz radiation output. The latest research was published online Feb. 27 in Nature Photonics.
Known as the fourth generation of light source, free electron laser can provide high brightness coherent radiation from the far infrared to the X-ray band. It has unprecedented revolutionary application value in physics, chemistry, materials science and life science. The traditional free electron laser generates a high-energy electron beam based on a radio-frequency accelerator, and then uses an undulator made of periodically arranged magnets to wiggle and modulate the electron beam and finally radiate high-intensity coherent radiation. Both radio frequency electronic accelerators or electronic oscillators composed of periodic magnets are bulky and expensive. The development of miniaturized, low-cost, next-generation free-electron lasers, including desktop-based electron accelerators and wavers, is a major goal that the scientific community has long been dreamed of chasing.
The State Key Laboratory of Laser Physics, Shanghai Institute of Optics and Fine Mechanics conducted a long-term and unremitting exploration in the research of new principles and new concepts of ultra-short laser-driven desktop high energy electron accelerator and undulator. Following the major achievement of record-high-brightness, high-quality electron beam electron acceleration in the super-short-laser-driven laser tail wave field in 2016, the team returned to the new ultra-short and ultra-short laser driven miniature, transient undulator Conceptual research has made major breakthroughs in the original, the first successful construction of a fully light-driven wire waveguide spiral undulator and achieve amplification of the strong THz radiation output. In this work, researchers use a super-short ultra-short laser beam to irradiate a metal target and produce targeted high-energy electron emission through laser-plasma interaction. At the same time, an extremely strong A radial transient electric field; the electric field directing a large number of high-energy electrons emitted in the vicinity of the wire to propagate along the wire and perform periodic helical motion equivalent to helical motion of the electron beam in a micro-undulator. This movement produces strong THz radiation with conversion efficiencies above 1%. In the experiment, the energy of electron beam is ~ 100 keV and the period of transient undulator is about 650 μm. By changing the diameter of wire, the radial electric field can be changed to change the undulator period, and the frequency tunable near single period broadband THz radiation ; By changing the length of the wire, the nonlinear amplification effect of THz radiation intensity with the transmission distance was first observed, and the magnification is more than 10 times. This strong THz radiation source is expected to have important applications in the exploration of materials. In this study, both the electron beam and the undulator are generated simultaneously by the same laser. The new concept of the undulator is expected to be further expanded and has been applied in fields such as short-wavelength and even X-ray free electron lasers.
The reviewers spoke highly of this result, stating "This paper describes a new approach to generate high-energy quasi-single-cycle THz pulses, a stunning concept that is an important and efficient new method of generating THz." "This paper not only clarifies the experimental dependence of the THz emission spectrum on the diameter of the wire but also explains the causes of THz radiation. This paper will attract a wide range of applications including lasers, electrodynamics (THz waves), electron beams, undulator Free electron laser and other fields of interest. "
It is reported that in this study, Nankai University, such as Weiwei Liu THz radiation measurement provides advanced testing equipment and cooperate to carry out the relevant experiments.
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