| 摘要 |
PROBLEM TO BE SOLVED: To provide a device and a method for measuring a Brillouin gain spectrum that do not require an expensive frequency shifter such as a SSB (Single Side Band) modulator and a delay fiber.SOLUTION: A method for measuring a Brillouin gain spectrum of the present invention comprises: a first light source (1) outputting probe light; a second light source (2) outputting pump light; a phase difference control unit (3) for changing a phase difference between the probe light and the pump light; a first light detector (17) receiving light containing Brillouin scattering light in a measured optical fiber (6); a second light detector (15) receiving multiplexed light composed of the probe light and the pump light; a frequency discriminator (21) outputting a voltage value according to a frequency of an output signal from the second light detector; and a subtractor (26) outputting a voltage according to a difference between a set reference voltage value and a voltage value output by the frequency discriminator. A central frequency of probe light or pump light is changed so as to reduce a voltage value output by the subtractor. |
