Haitao Fan

Note: A new angle-resolved proton energy spectrometer

In typical laser-driven proton acceleration experiments Thomson parabola proton spectrometers are used to measure the proton spectra with very small acceptance angle in specific directions. Stacks composed of CR-39 nuclear track detectors, imaging plates, or radiochromic films are used to measure the angular distributions of the proton beams, respectively. In this paper, a new proton spectrometer, which can measure the spectra and angular distributions simultaneously, has been designed. Proton acceleration experiments performed on the Xtreme light III laser system demonstrates that the spectrometer can give angle-resolved spectra with a large acceptance angle. This will be conductive to revealing the acceleration mechanisms, optimization, and applications of laser-driven proton beams.

Generation of broadband 17-μJ mid-infrared femtosecond pulses at 3.75 μm by silicon carbide crystal

In this contribution, we report the generation of 17-μJ mid-infrared (MIR) pulses with duration of 70 fs and bandwidth of 550 nm centered at 3.75 μm at 1-kHz repetition rate, by a two-stage femtosecond optical parametric amplifier utilizing 4H-silicon carbide crystal as the nonlinear medium. The crystal is selected as it processes orders of magnitude higher damage threshold than traditional MIR nonlinear crystals, and it supports extreme broad parametric bandwidth. With its distinguished features such as MIR central wavelength, ultra-broad bandwidth, self-stable carrier-envelope phase, and potential for energy scaling, this kind of MIR source holds promise for new approaches to extreme short isolated attosecond pulse generation as well as MIR spectroscopy applications.

Angle-dependent modulated spectral peaks of proton beams generated in ultrashort intense laser-solid interactions

Proton acceleration from 4 μm thick aluminum foils irradiated by 30-TW Ti:sapphire laser pulses is investigated using an angle-resolved proton energy spectrometer. We find that a modulated spectral peak at ∼0.82 MeV is presented at 2.5° off the target normal direction. The divergence angle of the modulated zone is 3.8°. Two-dimensional particle-in-cell simulations reveal that self-generated toroidal magnetic field at the rear surface of the target foil is responsible for the modulated spectral feature. The field deflects the low energy protons, resulting in the modulated energy spectrum with certain peaks.

Generation of 17-μJ mid-infrared ultrafast laser pulses by SiC crystal based noncollinear optical parametric amplifier

A femtosecond OPA system for mid-infrared ultrafast laser is established. Pulse energy of 17-μJ is obtained from SiC crystal at central wavelength of 3.75-μm, which proves SiC an ideal nonlinear crystal for mid-infrared pulse generation.

High-contrast PW Ti:Sapphire laser system with a combined scheme of doubled CPA and NOPA

We generated laser power of 1.16PW from a Ti:sapphire laser facility by using a combined scheme of doubled chirped-pulse amplifier (DCPA) and non-collinear optical parametrical amplifier (NOPA). Laser energy up to 32.3J was obtained with the pulse duration was 27.9fs. By clean high-energy seeding pulse injection from the NOPA stage, contrast ratio of the main amplified laser pulse was improved to around 109 within the time scale of 400 picoseconds.

Generation of femtosecond laser pulse at 1053 nm with contrast ratio of 10 11 by optical-parametric amplification

We demonstrated a high contrast 1053 nm femtosecond laser by exchanging the signal and idler in two stages non-collinear optical-parametric amplifier, 60 uJ idler with measurement-limited contrast of 2.3×10 was obtained within sub-10 ps.

Generation of high contrast ultrashort intense 1053nm laser based on non-collinear optical parametric amplification

We report the experimental research on high contrast ultrashort intense laser with 3 stage OPAs pumped by 400nm laser, 30 uJ laser pulse at 1053nm was obtained by exchanging the signal and idler in each amplifier.