Fabrication method of a weak reflectivity fiber grating

Abstract

The invention provides a manufacturing method of a weak-reflectivity fiber grating. The manufacturing method comprises the steps that step 1: a germanium-doped single-mode fiber is put in a hydrogen device, pressure is set to be not greater than 8Mpa and time is not more than 1 day; step 2: the pressure of the hydrogen device is down-regulated to be within 4Mpa, and the fiber is taken out at the time of no more than 72h; step 3: the fiber is arranged in a baking box to be baked, temperature is not more than 85 DEG C and time is not more than 2h; step 4: a laser device is set in a way that frequency is within 20Hz and power is within 2.5mJ / Pulse; step 5: grating write-in is performed according to normal operation, depth is monitored online until performing of write-in reaches the saturated state and the transmission depth is not increased any longer; and step 6: the grating is arranged in the baking box to perform annealing. The manufacturing method is simple in manufacturing process without additional arrangement of any instrument or equipment. The weak fiber grating of which the reflectivity is 0.1% can be obtained through control of the hydrogen content in the fiber.

Description

technical field [0001] The invention belongs to the technical field of optical fiber distributed sensing, and relates to a manufacturing method of a fiber grating with isotactic weak reflectivity. Background technique [0002] Distributed optical fiber sensing technology is a new type of sensing technology that has developed rapidly in recent years. Its basic principle is to use the same optical fiber or connect a series of fiber grating sensors in series to transmit and sense signals. Changes in physical quantities such as temperature, vibration, and strain at different positions of the fiber are detected and located to achieve true distributed or quasi-distributed measurement. Because optical fiber sensing has incomparable advantages of other sensing technologies, such as anti-electromagnetic interference, anti-corrosion, high temperature resistance, etc., it can also provide the spatial distribution of the measured physical parameters along the entire optical fiber path a...

AI Technical Summary

Problems solved by technology

[0007] Based on the above-mentioned distributed optical fiber sensing technology, the signal detection part is roughly divided into two categories. One is to use the reflected light generated by the material defect of the optical fiber itself as the measurement signal. The signal optical power is very weak and requires a series of amplification. , noise reduction and other processing to get accurate measurement results, the measurement system is complex and costly

The second is to configure a series of fiber grating sensors in the measurement network. The reflectivity of ordinary gratings is very high, and the optical power attenuates quickly after being reflected by multiple gratings during transmission. Therefore, the number of gratings connected in series on one optical fiber Generally, it cannot exceed dozens. In order to increase the number of gratings in series, such as wavelength division multiplexing, code division multiplexing, frequency division multiplexing and other technologies are introduced, the system is complicated and the cost is high.

But the expansion effect is not ideal and the application is very limited