Liu Yunquan's research group has made new progress in the generation and control of high-order harmonics with lateral angular momentum

Professor Liu Yunquan’s group from Peking University School of Physics and State Key Laboratory of Artificial Microstructures and Mesoscopic Physics proposed to obtain controllable lateral orbital angular momentum extreme ultraviolet high-order harmonics based on ultra-short high-intensity spatiotemporal optical vortex beams (Spatiotemporal Optical Vortex, STOV) The wave generation (High Harmonic Generation, HHG) method has discovered the characteristic spectral structure of the harmonics generated by the spatiotemporal vortex beam, revealing its internal physical mechanism

Orbital Angular Momentum (OAM) of photons is one of the important physical quantities that describe the quantum state of photons

Utilizing the vortex optical field carrying longitudinal orbital angular momentum to drive high-order harmonic generation (OAM-HHG for short) is an important means to prepare and control the extreme ultraviolet vortex beam

Professor Yunquan Liu’s group studied the physical process of ultra-short high-intensity space-time vortex beams driving high-order harmonic generation (STOV-HHG), and obtained the characteristic spectral structure of harmonic radiation [Figure 1(c)], and revealed Its inherent physical mechanism

Based on the precision time-frequency two-color light field synthesis technology developed in the early stage, the research group further proposed a new reverse spin-reverse vortex two-color space-time vortex beam , Found that the use of this beam can effectively control the space-time topological charge of the extreme ultraviolet beam, providing an important way for experimentally generating extreme ultraviolet beams with controllable lateral orbital angular momentum (Figure 2)

Figure 1.

Figure 2.

Fang Yiqi, a 2017 doctoral student in the School of Physics, Peking University, is the first author, and Liu Yunquan is the corresponding author

The above-mentioned research work was supported by the National Natural Science Foundation of China, Beijing Quantum Information Science Research Center, Extreme Optics Collaborative Innovation Center, and Yangtze Delta Optoelectronics Research Institute of Peking University