Great progress has been made in the measurement of ultrashire laser pulse field in Xi 'an Institute of Optics and Machinery

Recently, the attosecond Science and Technology Research Center of Xi 'an Institute of Optics and Machinery has made important progress in ultrashort laser pulse field measurement. The research team innovatively proposed a third-order nonlinear process all-optical sampling method based on perturbation. The measured pulse width of this method is as short as subperiodic, the band covers deep ultraviolet to far infrared, and it has the advantages of simple and stable system structure and simple data processing. The two studies were published in Optics Letters. The first authors are Pei Huang, a special research assistant, and Hao Yuan, a doctoral student. The corresponding authors are Huabao Cao and Yuxi Fu.

Ultrashort laser pulse is an important tool to explore the microcosmic world of matter and generate attosecond pulse. Generally speaking, the commonly used characterization techniques can be divided into frequency domain measurement and time domain measurement. In the frequency domain, the main methods include frequency resolved optical gating (FROG), spectral phase interferometry (SPIDER) and dispersion scanning (D-SCAN). By measuring the spectral information generated by the nonlinear process, the pulse width and phase of the ultra-short pulse can be obtained indirectly. This kind of method is widely used because the device is simple and easy to build, but usually requires complex inversion iterative algorithm, and it is difficult to obtain the photoelectric field information, and limited by the phase matching mechanism, it is difficult to apply to the laser pulse measurement above frequency range. However, the measurement method based on time-domain sampling is usually not restricted by the strict phase matching, and is sensitive to the electric field waveform, which can be used to directly measure the photoelectric field, and has a good development momentum in recent years. The research team proposes that the all-optical sampling method based on perturbation third-order nonlinear process is a time-domain sampling method. In the experiment, the transient grating effect (TGP) and the Air tripling effect (Air-ThG) are used respectively to accurately measure the output multi-period pulses (750-850nm, 25fs), based on the low-period pulse generated by the aerated hollow fiber post-compression technology (600-1000nm, 7.2fs) and the dual-chirped optical parametric amplification system (1300-2200nm, 15fs), the ultra-short pulse measurement covering the visible, near infrared to mid-infrared bands is realized, which can meet the requirements of ultra-short pulse measurement in different bands.

FIG. 1 Schematic diagram of experimental device

FIG. 2 Measurement results of periodic pulse in visible band

FIG. 3 Measurement results of periodic pulse in mid-infrared band

Source: Xi 'an Institute of Optics and Fine Mechanics, CAS