A propagation property analyzing apparatus that analyzes propagation properties of a few-mode optical fiber that multiplexes a plurality of modes, which is an optical fiber under test, in a lengthwise direction thereof, through Brillouin time domain analysis, the propagation property analyzing apparatus comprising:
- means for inputting probe light in a desired mode from one end of the optical fiber under test;
- first optical frequency control means for outputting pump light having a frequency difference equivalent to a Brillouin frequency shift in the desired mode, relative to the probe light;
- first light pulse formation means for forming light pulses from the probe light;
- second optical frequency control means for outputting second probe light having a frequency difference equivalent to a Brillouin frequency shift in an other mode different from the desired mode, relative to the probe light;
- second light pulse formation means for forming light pulses from the second probe light;
- and
- mode selection and multiplexing/demultiplexing means for inputting, from an other end of the optical fiber under test, the light pulses of the probe light in the desired mode and the light pulses of the second probe light in the other mode respectively.