RAMAN GAIN MEASURING METHOD AND DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a method and a device capable of measuring the Raman gain highly accurately even in a low Raman gain region, and a method and a device capable of measuring the Raman gain without requiring high-power pumping light.

SOLUTION: This Raman gain measuring method comprises following steps: a probe LD 10 outputs probing light which is continuous (CW) laser light having the wavelengthλs to an optical fiber transmission path 12; an excitation laser diode (excitation LD) 14 generates Raman pumping light having the wavelengthλp; the optical fiber transmission path 12 is excited by the pumping light on/off-modulated by an optical switch 16; the probe light propagating through the optical fiber transmission path 12 is transmitted through an optical band-pass filter 22 and inputted into a light receiving element 24; an output electric signal of a light receiving element 24 is inputted into a detector 26 for detecting an alternating-current component and a low-pass filter 28 for detecting a direct-current component; and an operation circuit 30 calculates the Raman gain using the output from the detector 26 and the LPF 28.

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