Abstract
We report a framing imaging based on noncollinear optical parametric amplification (NCOPA), named FINCOPA, which applies NCOPA for the first time to single-shot ultrafast optical imaging. In an experiment targeting a laser-induced air plasma grating, FINCOPA achieved 50 fs-resolved optical imaging with a spatial resolution of ∼83 lp / mm and an effective frame rate of 10 trillion frames per second (Tfps). It has also successfully visualized an ultrafast rotating optical field with an effective frame rate of 15 Tfps. FINCOPA has simultaneously a femtosecond-level temporal resolution and frame interval and a micrometer-level spatial resolution. Combining outstanding spatial and temporal resolutions with an ultrahigh frame rate, FINCOPA will contribute to high-spatiotemporal resolution observations of ultrafast transient events, such as atomic or molecular dynamics in photonic materials, plasma physics, and laser inertial-confinement fusion.
Highlights
Compressed ultrafast photography (CUP)[16] can work at a frame rate of 0.1 trillion frames per second (Tfps) with a temporal resolution of ∼50 ps by applying a compressedsensing-based algorithm to the data acquired by a streak camera, and its spatial resolution can be scaled to 7 lp∕mm.[15]
The temporal resolution is about 50 fs, estimated using the idler pulse duration measured with our homemade SPIDER, whereas the spatial resolutions depend on the spatial bandwidth of the optical parametric amplifiers and the optical imaging system including OIS-1 to OIS-4 and L1 to L4
Comparing the blue marks with the red marks, we find that the evolution of the plasma grating from the two methods well coincides, which demonstrates the validity of FINCOPA
Summary
It is invaluable to discover and understand ultrafast dynamic processes, e.g., femtosecond laser ablation for precise machining and manufacturing,[1] fast ignition for inertial-confinement fusion,[2] laser filaments for atmospheric analysis,[3] shockwave interactions in living cells,[4] chemical reactions and soliton molecule dynamics,[5,6,7] semiconductor thermal dynamics, and photosynthetic light harvesting.[4,8] As a result, ultrafast optical imaging, which can realize blur-free visualization of transient dynamics, has attracted considerable attention for decades from researchers in many fields, such as physics, chemistry, optical engineering, industrial manufacturing, energy, materials science, and biomedicine.[9]. The successive images are sampled by a series of discrete daughter pulses with different spectral bands generated from a single broadband pulse, so some constraints exist among the temporal resolution, frame interval, and frame number.[4,22,23,24] By utilizing spectral filtering in STAMP, i.e., SF-STAMP,[24] the frame rate increases further to 7.5 Tfps with a frame number of 25, which results in a sacrifice of the temporal resolution, at 465 fs. All-optical coaxial framing photography (AOCFP)[26] can realize single-shot optical imaging for both phase and amplitude information with parallel coherence shutters It has a frame rate of 8 Tfps and a temporal resolution of about 40 fs, depending on the femtosecond pulse used.[27] A constraint exists in AOCFP, where increasing the frame number will result in degradation of the interference contrast. FINCOPA is a good candidate for single-shot imaging with high spatial and temporal resolutions, as it offers a high frame rate as well as a large frame number, simultaneously
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