Ultra-short femtosecond pulse in-situ measurement method based on interference fringes

Abstract

The invention belongs to the field of ultrafast laser, and particularly relates to an ultrashort femtosecond pulse in-situ measurement method based on interference fringes, which comprises the following steps: dividing an original ultrashort femtosecond pulse into two beams, one beam is used as a pulse to be measured, and the other beam is used for generating higher harmonics to obtain an extreme ultraviolet attosecond pulse or a pulse string thereof; controlling relative time delay between the extreme ultraviolet attosecond pulses or pulse strings thereof and the to-be-detected pulses, and then combining and focusing on the rare gas to interact with the rare gas; optical interference between attosecond extreme ultraviolet pulses and photons radiated by rare gas atoms in a virtual state results in interference fringes above a single ionization threshold of the rare gas atoms in a transmission spectrum. The perturbation theory shows that the fringes record the self-convolution of the ultra-short femtosecond pulse in the frequency domain, and can be used for directly representing the ultra-short femtosecond pulse without a reconstruction algorithm. The all-optical in-situ measurement method is simple and convenient and is used for directly measuring femtosecond pulses, and any few-period laser pulses can be measured.

Description

technical field [0001] The invention belongs to the field of ultrafast lasers, and more specifically relates to an in-situ measurement method of ultrashort femtosecond pulses based on interference fringes. Background technique [0002] Broadband femtosecond pulses are particularly important for their broad applications in quantum state manipulation in atomic systems, coherence modulation in photochemical reactions, and photoinduced phase transitions in condensed matter. Regarding pulse amplitude and phase information, they are usually prerequisites for triggering light-matter interactions. The most commonly used method for the complete characterization of laser pulses is frequency-resolved optical gate (FROG). To recover the missing phase information in the measured spectrogram, the phase retrieval algorithm is used iteratively, usually converging to the correct solution for the pulse. In addition, existing studies have developed other methods, such as spectral phase inter...

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Problems solved by technology

[0004] Aiming at the defects and improvement needs of the prior art, the present invention provides an in-situ measurement method for ultrashort femtosecond pulses based on interference fringes, the purpose of which is to solve the problem of dispersion caused by nonlinear crystal materials in existing femtosecond pulse measurement methods As well as the technical problem of errors in the measurement of femtosecond pulses due to off-site measurement

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