Abstract: A vibration distribution measurement system includes a frequency sweep light source that outputs frequency sweep light, an optical splitter that splits the frequency sweep light into probe light and local light, an optical mixer that mixes backscattered light from the sensing fiber as signal light with the local light, the backscattered light being obtained by causing the probe light to be incident on the sensing fiber, and an analysis unit that analyzes a beat signal obtained from output light of the optical mixer. The analysis unit estimates a distance offset from a measurement result obtained by measuring a distribution waveform of the signal light by measuring the beat signal at a measurement time sufficiently shorter than a cycle of the vibration of the sensing fiber, and measures a distribution of a vibration at any position by compensating for the distance offset.

Abstract: Provided is an optical spectrum line width calculation method, apparatus, and program capable of calculating a spectrum line width of a laser to be measured from an optical interference signal generated by an optical interferometer having a delay line, based on a phase of the optical interference signal having a delay time longer than a delay time due to the delay line. The optical spectrum line width measurement apparatus includes a Mach-Zehnder interferometer, an optical receiver that receives an optical interference signal emitted from the Mach-Zehnder interferometer, an A/D converter that converts an analog electric signal output from the optical receiver into a digital electric signal, and an processing apparatus that processes the digital electric signal. In the interferometer, an optical delay fiber is provided on one arm waveguide, and an optical frequency shifter is provided on the other arm waveguide.

Abstract: An environmental property measurement apparatus includes a unit configured to receive probe light in a desired mode from one end of a measurement optical fiber, a unit configured to receive, from the other end of the measurement optical fiber, a light pulse in the desired mode as a pump light pulse with respect to the probe light, the light pulse having a frequency difference corresponding to a Brillouin frequency shift of the measurement optical fiber relative to the probe light on a high frequency side, and a unit configured to receive second probe light having the frequency difference corresponding to the Brillouin frequency shift of the measurement optical fiber relative to the probe light on a low frequency side from the other end of the measurement optical fiber, the second probe light being probe light with respect to the probe light in another mode different from the desired mode.

Abstract: An object is to provide a propagation property analyzing apparatus that can alleviate the influence of an error caused by crosstalk, and accurately evaluate a few-mode optical fiber that multiplexes a plurality of modes, in a distributional and non-destructive manner.