	US 11,815,421 B2
	Acoustic mode propagation speed measurement method and acoustic mode propagation speed measurement device
Yuto Sagae, Musashino (JP); Takashi Matsui, Musashino (JP); Kyozo Tsujikawa, Musashino (JP); and Kazuhide Nakajima, Musashino (JP)
Assigned to NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
Appl. No. 17/434,949
Filed by NIPPON TELEGRAPH AND TELEPHONE CORPORATION, Tokyo (JP)
PCT Filed Feb. 19, 2020, PCT No. PCT/JP2020/006395 § 371(c)(1), (2) Date Aug. 30, 2021, PCT Pub. No. WO2020/179440, PCT Pub. Date Sep. 10, 2020.
Claims priority of application No. 2019-038950 (JP), filed on Mar. 4, 2019.
Prior Publication US 2022/0170817 A1, Jun. 2, 2022
Int. Cl. G01M 11/00 (2006.01)

CPC G01M 11/319 (2013.01)

4 Claims

1. An acoustic mode propagation speed measurement method comprising: acquiring a frequency shift spectrum of Brillouin scattered light generated in an optical fiber; fitting the frequency shift spectrum using a Gauss function; acquiring a spectral full-width at half maximum w from a fitted curve using the Gauss function; and calculating a propagation speed V_Aof an acoustic mode of the optical fiber by substituting the acquired spectral full-width at half maximum w into a linear function of the spectral full-width at half maximum w and the propagation speed V_Aof the acoustic mode.