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1. Sub-picosecond timing jitter between optically synchronized femtosecond and picosecond laser systems

   https://doi.org/10.1088/1361-6501/acc41b  

   Jiang, Zhenfei; Strycker, Benjamin; Hand, Lucian; Adamonis, Jonas; Yi, Zhenhuan; Sokolov, Alexei; Scully, Marlan (March 2023, Measurement Science and Technology)

   Abstract Synchronized optical pulses are widely used. We report here characterization and measurement of synchronized femtosecond and picosecond pulses from a Ti:Sapphire laser (nominally 800 nm) and a Nd:YAG laser (1064 nm), respectively. Synchronization is achieved by utilizing soliton self-frequency shift in a photonic-crystal fiber that allows the 800 nm femtosecond oscillator to seed the third-harmonic generation (355 nm) of picosecond regenerative amplifier. The relative timing jitter between the amplified femtosecond and the third-harmonic generation of picosecond pulses is (710 ± 160) fs, which is only (1.17 ± 0.26)% of the picosecond pulse duration. This work paves way for applications in stimulated Raman scattering spectroscopy and amplification. 

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2. Picosecond laser electronic excitation tagging velocimetry using a picosecond burst-mode laser

   https://doi.org/10.1364/AO.419491  

   Zhang, Zhili; Jiang, Naibo; Slipchenko, Mikhail_N; Mance, Jason_G; Roy, Sukesh (April 2021, Applied Optics)

   Detailed characterizations of picosecond laser electronic excitation tagging (PLEET) in pure nitrogen ( ${\mathrm{N}}_2$) and air with a 24 ps burst-mode laser system have been conducted. The burst-mode laser system is seeded with a 200 fs broadband seeding laser to achieve short pulse duration. As a non-intrusive molecular tagging velocimetry (MTV) technique, PLEET achieves “writing” via photo-dissociating nitrogen molecules and “tracking” by imaging the molecular nitrogen emissions. Key characteristics and performance of utilization of a 24 ps pulse-burst laser for MTV were obtained, including lifetime of the nitrogen emissions, power dependence, pressure dependence, and local flow heating by the laser pulses. Based on the experimental results and physical mechanisms of PLEET, 24 ps PLEET can produce similar 100 kHz molecular nitrogen emissions by photodissociation, while generating less flow disturbance by reducing laser joule heating than 100 ps PLEET. 

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3. Picosecond Fresnel transmission electron microscopy

   https://doi.org/10.1063/1.4984586  

   Schliep, Karl B.; Quarterman, P.; Wang, Jian-Ping; Flannigan, David J. (May 2017, Applied Physics Letters)
4. Advanced picosecond precision Radio Frequency Timer

   https://doi.org/10.1088/1748-0221/19/02/C02014  

   Zhamkochyan, S.; Kakoyan, V.; Abrahamyan, S.; Elbakyan, H.; Ayvazyan, G.; Ayvazyan, R.; Ghalumyan, A.; Kakoyan, A.; Mayilyan, S.; Papyan, A.; et al (February 2024, Journal of Instrumentation)

   Abstract A new type of radio frequency (RF) timing technique is presented. It is based on a helical deflector, which performs circular or elliptical sweeps of photo- or secondary electrons, accelerated to keV energies, by means of RF fields in the 500–1000 MHz range. By converting a time distribution of the electrons to a hit position distribution on a circle or ellipse, this device achieves extremely precise timing, similar to streak cameras. Detection of the scanned electrons, using a position sensitive detector based on microchannel plates and a delay line anode, resulted in a timing resolution of 10 ps, which can be potentially improved to 1 ps. RF-Timer-based single photon and heavy ion detectors have potential applications in different fields of science and industry, which include high energy nuclear physics and imaging technologies. This technique could play a crucial role in developing of sub 10 ps Time-of-Flight Positron Emission Tomography. 

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5. Nonlinear Shaping in the Picosecond Gap

   https://doi.org/10.34133/ultrafastscience.0112  

   Lemons, Randy; Hirschman, Jack; Zhang, Hao; Durfee, Charles; Carbajo, Sergio (January 2025, Ultrafast Science)

   Lightwave pulse shaping in the picosecond regime has remained unaddressed because it resides beyond the limits of state-of-the-art techniques, due to either its inherently narrow spectral content or fundamental speed limitations in electronic devices. The so-called picosecond shaping gap hampers progress in all areas correlated with time-modulated light–matter interactions, such as photoelectronics, health and medical technologies, and energy and materials sciences. We report on a novel nonlinear method to simultaneously frequency-convert and adaptably shape the envelope of light wave packets in the picosecond regime by balancing spectral engineering and nonlinear conversion in solid-state nonlinear media, without requiring active devices. We capture computationally the versatility of this methodology across a diverse set of nonlinear conversion chains and initial conditions. We also provide experimental evidence of this framework producing picosecond-shaped, ultranarrowband, near-transform-limited light pulses from broadband, femtosecond input pulses, paving the way toward programmable lightwave shaping at gigahertz-to-terahertz frequencies. 

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