Ultrashort soft x-ray pulse-shape measurement using optical field ionization dynamics in noble gas

Katsuya Oguri; Hidetoshi Nakano; Tadashi Nishikawa; Naoshi Uesugi

doi:10.1117/12.448475

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14 November 2001 Ultrashort soft x-ray pulse-shape measurement using optical field ionization dynamics in noble gas

Katsuya Oguri, Hidetoshi Nakano, Tadashi Nishikawa, Naoshi Uesugi

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Proceedings Volume 4504, Applications of X Rays Generated from Lasers and Other Bright Sources II; (2001) https://doi.org/10.1117/12.448475
Event: International Symposium on Optical Science and Technology, 2001, San Diego, CA, United States

Abstract

We propose a cross-correlation technique for measuring the shape of an ultrashort soft x-ray-pulse using the rapid change in the Kr⁺ population that occurs during optical field-induced ionization. By calculating the time evolution of the Kr charge states during ionization, we showed that the increase in the Kr⁺ population operates as 'switch', and the transient state of Kr⁺ during the sequential ionization operates as 'sampling gate' for measuring a soft x-ray-pulse shape. The temporal resolution of this technique is expected to overcome the limitation imposed by the ionizing laser pulse duration as a result of the ultrafast nature of optical field-induced ionization. Using the 'switch' operation, we measured a soft x-ray-shape pulse are 15.6 nm emitted from W plasma produced by a 100-fs laser pulse. Assuming a Gaussian temporal profile, we found the soft x-ray-pulse duration to be about 4 ps. This result is in good agreement with the duration measured with an x-ray streak camera thus configuring the feasibility of this 'switch' operation. The 'sampling gate' operation will be useful for directly measuring the original pulse shape of a femtosecond soft x-ray.

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Katsuya Oguri, Hidetoshi Nakano, Tadashi Nishikawa, and Naoshi Uesugi "Ultrashort soft x-ray pulse-shape measurement using optical field ionization dynamics in noble gas", Proc. SPIE 4504, Applications of X Rays Generated from Lasers and Other Bright Sources II, (14 November 2001); https://doi.org/10.1117/12.448475

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