High-speed 100 MHz strain monitor using fiber Bragg grating and optical filter for magnetostriction measurements under ultrahigh magnetic fields

Akihiko Ikeda; Toshihiro Nomura; Yasuhiro H Matsuda; Shuntaro Tani; Yohei Kobayashi; Hiroshi Watanabe; Keisuke Sato

doi:10.1063/1.4999452

High-speed 100 MHz strain monitor using fiber Bragg grating and optical filter for magnetostriction measurements under ultrahigh magnetic fields

Rev Sci Instrum. 2017 Aug;88(8):083906. doi: 10.1063/1.4999452.

Authors

Akihiko Ikeda¹, Toshihiro Nomura¹, Yasuhiro H Matsuda¹, Shuntaro Tani², Yohei Kobayashi², Hiroshi Watanabe³, Keisuke Sato⁴

Affiliations

¹ International MegaGauss Science Laboratory (IMGSL), Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Japan.
² Laser and Synchrotron Research Center (LASOR), Institute for Solid State Physics (ISSP), University of Tokyo, Kashiwa, Japan.
³ Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.
⁴ Department of Natural Science, Ibaraki National College of Technology, Hitachinaka, Japan.

PMID: 28863652
DOI: 10.1063/1.4999452

Abstract

A high-speed 100 MHz strain monitor using a fiber Bragg grating, an optical filter, and a mode-locked optical fiber laser has been devised, whose resolution is ΔL/L∼10^-4. The strain monitor is sufficiently fast and robust for the magnetostriction measurements of materials under ultrahigh magnetic fields generated with destructive pulse magnets, where the sweep rate of the magnetic field is in the range of 10-100 T/μs. As a working example, the magnetostriction of LaCoO₃ was measured at room temperature, 115 K, and 7 ∼ 4.2 K up to a maximum magnetic field of 150 T. The smooth dependence on the squared magnetic field and the first-order transition were observed at 115 K and 7 ∼ 4.2 K, respectively, reflecting the field-induced spin state evolution.