Optical fiber bending mode elimination device and method

Abstract

The invention discloses a fiber bending mode eliminating device and method; a multi-mode fiber is wound with an inner winding tool and an outer winding tool by means of double-curvature winding, so that the multi-mode fiber forms a small-radius winding portion wound on the inner winding tool and a large-radius winding portion wound on the outer winding tool. The multi-mode fiber is used as a transmission medium and is pre-wound according to two different radiuses, a higher-mode component coupled into the fiber is attenuated effectively with the small-radius winding portion, bending transmission mode possibly excited in previous step is eliminated with the large-radius winding portion, the inhibition on higher mode by the multi-mode fiber is achieved, output optical intensity is stable, an optical signal with mode eliminated outputs optical power that is kept constant during fiber moving, and using additional other detectors to assist in measuring position and other reference information during measurement of a scintillator position-sensitive nuclear detector is not required accordingly.

Description

technical field [0001] The invention belongs to the field of nuclear physics detection. The invention is an optical fiber mode elimination device for optical transmission in a neutron scintillator position-sensitive detector calibration system, especially related to the scene where the output intensity is required to be stable, so that most of the high-order modes of the laser light source can The components of the optical fiber are sufficiently attenuated to ensure that the output optical power of the fiber is stable during the movement. Background technique [0002] Although there are many types of large-area imaging scintillator neutron detectors, the basic principles are similar, and the detection of particles is realized through fluorescence excitation and photoelectric conversion. The neutron scintillator position-sensitive detector is mainly composed of scintillation screen, wave-shifting optical fiber, photomultiplier tube, etc. The scintillator absorption wavelengt...

AI Technical Summary

Problems solved by technology

[0005] The inner diameter of the single-mode fiber is limited to the range of the transmission wavelength, which is not only difficult to manufacture and high in cost, but also not conducive to the transmission of power, and there are also matching restrictions on the light source

Once the inner core diameter is expanded to transmit higher power, or the transmission light source is replaced in different measurement occasions, the wavelength will change, which will lead to the introduction of high-order modes and destroy the original stability guarantee

In addition, on some special bending radii, there are unique transmission modes, and the attenuation coefficient of the corresponding mode will decrease sharply

The above two sources lead to the limitations of single-mode optical fiber transmission of analog signals, and are also the reason why multi-mode optical fibers cannot guarantee stable long-distance transmission of constant analog signals

[0006] Furthermore, in order to calibrate each channel of the photomultiplier tube, the output optical fiber needs to be fixed on a mechanical platform, and the entire wave-shifting optical fiber plane is scanned. In this way, during the scanning movement, the optical fiber is bent, resulting in inconsistent optical output power at different positions. , loses the meaning of calibration

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