US 12,442,716 B2
Optical fiber test method and optical fiber test equipment
Tomokazu Oda, Musashino (JP); Atsushi Nakamura, Musashino (JP); Yusuke Koshikiya, Musashino (JP); and Nazuki Honda, Musashino (JP)
Assigned to NTT, Inc., Tokyo (JP)
Appl. No. 18/289,755
Filed by NTT, Inc., Tokyo (JP)
PCT Filed Jun. 4, 2021, PCT No. PCT/JP2021/021428
§ 371(c)(1), (2) Date Nov. 7, 2023,
PCT Pub. No. WO2022/254712, PCT Pub. Date Dec. 8, 2022.
Prior Publication US 2024/0264034 A1, Aug. 8, 2024
Int. Cl. G01M 11/02 (2006.01)
CPC G01M 11/02 (2013.01) 2 Claims
OG exemplary drawing
 
2. An optical fiber test device that measures a maximum loss of a higher-order mode at a connection point of a few-mode optical fiber, the optical fiber test device comprising:
a light source unit that allows probe light, which has a tunable wavelength and is continuous light, to enter one end of the few-mode optical fiber in a fundamental mode and allows pulsed pump light, which is shifted to a high frequency side by a frequency at which a Brillouin interaction occurs with respect to the probe light, to enter the other end of the few-mode optical fiber in a higher-order mode as a measurement target; and
an analysis unit that acquires, from a light intensity of the probe light amplified by the pump light, a time waveform of an amplification component of the probe light amplified by the pump light, calculates a connection loss of the pump light at the connection point from a ratio of the amplification components before and after the connection point, acquires a wavelength dependency of the connection loss, detects a maximum value of the connection loss from the wavelength dependency of the connection loss, and sets the maximum value as a maximum loss of the higher-order mode at the connection point.