Research On Advanced Terahertz Synchrotron Radiation Sources Based On Laser-electron Interaction

The generation and application of terahertz radiation are accelerating the development of scientific research in related areas.It provides a new tool for detecting and controlling quasi-particle and collective excitation in solids,driving the related changes of phase transition and material properties,and studying the rotation and vibration in molecular systems.Among them,the emergence of ultrafast strong-field terahertz pulse source opens the door to the control of reaction and process.This terahertz pulse can drive the new dynamic state of matter,showing a completely different nature from the equilibrium state.In the meanwhile,the coherent control of quantum systems and the study of magnetization material put forward new requirements for advanced terahertz radiation sources.The development of terahertz light sources with frequency chirp and orbital angular momentum will promote the development and innovation of related research.Terahertz synchrotron radiation source based on electron storage ring has the obvious advantages of high power,high repetition rate and full spectrum coverage,and it has great potential in developing into a comprehensive research platform of the terahertz photonics science for related disciplines.The manipulation technology based on laser-electron interaction in the community of free electron laser has brought new possibilities to the advanced terahertz synchrotron radiation source on the storage ring,and its high-precision synchronization performance with external laser has laid the foundation for the development of related experimental methodology.In this thesis,utilizing the laser-electron interaction,the radiation mechanism of advanced terahertz synchrotron radiation sources is explored.Combined with theoretical calculation and numerical simulation,three kinds of terahertz radiation sources with unique performance are proposed:controllable frequency chirp,ultrashort strong-field pulse radiation,and vortex light carrying orbital angular momentum.For frequency-chirped terahertz radiation,a laser shaping method is proposed in this thesis to control the chirp of the laser intensity envelope,and through the laserelectron interaction,the envelope is transferred to the longitudinal distribution of the electron beam to realize the frequency chirp control of terahertz synchrotron radiation.This thesis also analyzes and simulates the radiation process of this electron beam,and discusses how to maintain the chirped phase during the extraction process.For ultrashort strong-field terahertz pulse,this thesis firstly proposes a double energy modulation scheme with energy-chirped electron beams.By using two dispersion sections,the electron beam with chirped interval can be obtained by modulating the electron beam with two seed lasers sequentially,and the ultrashort terahertz radiation can be obtained under the slippage-boosted radiation mechanism.In order to improve the feasibility and the compatibility with the complex lattice of the electron storage ring,a direct single modulation scheme with an external shaped laser is further proposed.The design of a taper undulator with controllable polarization is also given,which is expected to realize the control of the spin angular momentum of ultrashort strong-field terahertz radiation.Besides,a numerical simulation method based on vector diffraction integral is developed to implement the complete spatio-temporal description of ultrashort terahertz pulses in focusing process.For terahertz vortex light with orbital angular momentum,a harmonic modulation method using helical undulator is firstly proposed.The electron beam with helical microbunching is generated by two laser harmonic modulations in succession.On this basis,a single modulation method through external shaped vortex laser is further proposed,which greatly expands the adjustment range of topological charge of orbital angular momentum.This thesis also analyzes and discusses the radiation performance of helically microbunched electron beam in bending radiation,transition radiation and undulator radiation.In fact,these advanced terahertz radiation schemes have similar characteristics.All of them can realize the manipulation of the electron beam by an external shaped laser under the laser-electron interaction.For chirped terahertz radiation and ultrashort strongfield terahertz radiation schemes,they both can be treated as a longitudinal manipulation on the electron beam;for terahertz vortex light scheme,it extends the manipulation from longitudinal dimension to transverse dimension.The modular implementation of these schemes can provide a reference for the related research on accelerator devices with laser modulation system.We expect that the practice of this terahertz radiation source based on the three-dimensional manipulation of the electron beam will provide a new tool and bring new opportunities for the development of terahertz photonic science.