A Method for Measuring the Absorption Coefficient of Few-Mode Erbium-doped Optical Fiber

Abstract

The invention discloses a method for measuring the absorption coefficient of a few-mode erbium-doped optical fiber. Under the pumping condition of the fundamental-mode optical fiber, the fundamental-mode signal light is obtained by measuring the input and output signal light and pump light power of the few-mode erbium-doped optical fiber. gain, and calculate the number of particle number inversions; then change the power of the pump light, measure the change curve of the gain with the particle number inversion, and then fit the ρ according to the curve l Gain G when =0 0 , so as to calculate the absorption coefficient of the fundamental mode optical signal; finally, according to the erbium ion concentration and refractive index distribution of the few-mode erbium-doped fiber, calculate the mode field distribution of each mode, and then calculate the few-mode Absorption coefficient of high-order mode signal light in Erbium-doped fiber.

Description

technical field [0001] The invention belongs to the technical field of optical communication, and more specifically relates to a method for measuring the absorption coefficient of a few-mode erbium-doped optical fiber. Background technique [0002] At present, based on technologies such as wavelength division multiplexing, polarization multiplexing, and multi-level modulation, the transmission capacity of a single fiber can reach 100 Tbit / s, and the transmission capacity of single-mode fiber (SMF) is close to Shannon's limit. To further increase the transmission capacity of optical fibers, it is necessary to utilize a new optical fiber dimension—spatial mode. The mode-division multiplexing (MDM) technology based on few-mode fiber has great potential in improving transmission capacity, and has continuously attracted attention at home and abroad. [0003] The WDM long-distance transmission system based on single-mode fiber is inseparable from the traditional erbium-doped fibe...

AI Technical Summary

Problems solved by technology

Traditionally, the insertion method or the shearing method is used to experimentally measure the absorption coefficient of the erbium-doped fiber. For the few-mode fiber, when the optical signal of the mode to be tested is injected into the few-mode erbium-doped fiber, other crosstalk modes are usually excited, resulting in the insertion method inaccurate measurements

The shearing method will cause loss to the optical fiber and increase the cost of the experiment, especially at the present stage, the price of the few-mode erbium-doped fiber is still very expensive, about 30-50 times that of the single-mode erbium-doped fiber

More importantly, due to the absorption effect of erbium ions in the few-mode erbium fiber, the measurement results of these traditional methods will further introduce errors

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