Recently, the Joint Laboratory of High Power Laser Physics, Shanghai Institute of Optical Mechanics, Chinese Academy of Sciences (SIOM), has made research progress in single-shot ultrafast kinetic diagnosis, and the related research results are summarized as "Single-shot spatiotemporal plasma density diagnosis using an arbitrary time-wavelength-encencoder". The research results were published in Optics and Lasers in Engineering under the title of "Single-shot spatiotemporal plasma density diagnosis using an arbitrary time-wavelength-encoded biprism interferometer".
Ultrafast dynamics phenomena exist widely in the fields of photochemistry, spintronics, plasma physics, laser processing, etc. Ultrafast dynamics diagnostics is an important tool to visualize the evolution process of ultrafast dynamics phenomena, which can be used to quantitatively study the mechanism of the ultrafast evolution process, reveal the principle of the ultrafast evolution process, and realize the role of quantitative feedback in the regulation of the ultrafast evolution process. However, it is difficult for the current single ultrafast dynamics diagnostic techniques to simultaneously combine the advantages of high spatiotemporal resolution, high sequence depth, independently adjustable time window, and no need for a reference arm.
In this work, the researchers propose the temporal wavelength-encoded biprism interferometer (TWEBI), which is based on the principle of generating wavelength-encoded probe light by cascading nonlinear crystals with different phase-matching angles, realizing wavelength spatial multiplexing by using two-dimensional diffractive optics elements (DOEs) and narrow-bandpass interferometric filters (IBPFs), and utilizing plug-and-play biprism interferometers to realize the shadowing recording mode and the phase On-demand switching of shadow recording mode and phase measurement mode is realized using a plug-and-play biprism interferometer. The experiments were carried out on the front-end of the optical parametric chirped pulse amplification of the Shenlight II femtosecond digital tiles, in which the TWEBI device achieved a spatial resolution of 4 um, a temporal resolution of 200 fs, a sequence depth of 12, an effective frame rate of up to 5 Tfps, and an arbitrarily adjustable time window from sub-picoseconds to 1.86 ns. Shadow recordings and densitometric measurements of the dynamics of laser-induced air filamentation were performed with the TWEBI device, and the related experimental results demonstrated the feasibility of the method. This work provides a potential solution for diagnosing complex transient dynamics, which will help us further understand, regulate, and apply these ultrafast phenomena.
The related work was supported by the National Natural Science Foundation of China (NSFC), the Foundation of Chinese Academy of Sciences (CAS), the Foundation of Shanghai Science and Technology Commission (SSTC), and the Foundation of the Ministry of Science and Technology.
Figure 1 (a) TWEBI experimental setup; (b) probe light spectra; (c) probe light time-domain amplitude and phase maps; (d) spatial resolution of the imaging system
Fig. 2 (a) Shadow map of laser-induced air filamentation; (b) wavelength map of the center of the subluminous spot; (c) phase and amplitude map of laser-induced filamentation; (d) reconstructed plasma density distribution
