Recently, the State Key Laboratory of Strong-Field Laser Physics at the Shanghai Institute of Optics and Precision Machinery (SIPM) of the Chinese Academy of Sciences (CAS) has made new progress in terawatt cycle-scale short-wave infrared vortex pulse generation. The research team combined a novel optical field modulation technique with optical parametric chirped pulse amplification (OPCPA) to realize high-energy vortex laser output. Based on the cascaded thin-film nonlinear pulse post-compression technique, the output of short-wave infrared vortex pulses at the terawatt period scale was realized for the first time. The results were published in Ultrafast Science under the title "Terawatt-Class Few-Cycle Short-Wave Infrared Vortex Laser".
Vortex light is a spatially structured beam with a helical wavefront, which has been widely used in quantum information, super-resolution microscopy, and optical tweezers due to its toroidal spatial intensity distribution and its characteristic of carrying orbital angular momentum. In addition, coupling orbital angular momentum into ultra-intense ultrashort lasers can provide powerful technical support and brand-new experimental means for vortex strong-field physics and nonlinear vortex phenomena. Vortex lasers of high intensity period scale have a wide range of applications in driving vortex particle beams and secondary radiation (e.g., isolated attosecond optical vortices, terahertz vortices). However, the generation of high-intensity ultrashort vortex pulses is still in the exploratory stage due to the difficulty in maintaining the vortex phase structure for laser amplification and compression.
Fig. 1 Diagram of the experimental setup
Fig. 2 (a, c, e) First-, second-, and third-order vortex spot maps of the amplified output of OPCPA; (b, d, f) Column lens focal stripes of the vortex beam.
In this study, the researchers realized a high-energy vortex laser output of 1.45 μm by combining spatial phase modulation with OPCPA technique and verified the transmission stability of the output vortex laser in space. Based on the cascaded thin-film post-pulse compression technique, a terawatt-scale period-scale short-wave infrared vortex pulse output of 13.7 mJ/10.59 fs is realized for the first time without destroying the vortex phase structure. This scheme can provide technical support for nonlinear vortex phenomena and provide a basis for the study of ultrafast orbital angular momentum physics.
Fig. 3 Time-domain measurement of the compressed vortex pulse
