Realizing method of pi/2 phase bias of optical fiber interferometer

Abstract

The invention belongs to the fields of optical fiber sensing and measuring technologies, in particular to a realizing method of the pi / 2 phase bias of an optical fiber interferometer. The phase bias is generated by arranging a special optical fiber branching unit with the length and the width of 3 in an interference optical path structure; the optical intensities of output ports of the branching unit are respectively 20 percent, 40 percent and 40 percent of total output light; and the pi / 2 phase bias can be obtained by a proper optical path connection. The invention realizes the pi / 2 (positive or negative) phase bias with a pour optical path method and obtains high measuring sensitivity and linear segment measuring range. The invention is not only suitable for an interference system with same interference optical paths and opposite transmission directions, such as interference systems of Sagnac rings, single-core feedback types, and the like, and can also provide the phase bias for an M-Z optical fiber interference structure.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensing and measurement, and in particular relates to a method for realizing π / 2 phase bias of an optical fiber interferometer. Background technique [0002] Optical fiber sensor is a sensor with optical fiber as functional material, which is the product of the development of laser technology and optical fiber communication technology. In recent years, due to the emergence of semiconductor lasers and low-loss optical fibers, fiber optic sensing technology has developed rapidly. [0003] The basic principle of optical sensors includes a variety of modulation techniques, including intensity modulation, frequency modulation, wavelength modulation, polarization modulation and phase modulation. Phase modulation, that is, interferometric optical sensors, has extremely high sensitivity and high precision. , occupies an important position in the field of optical sensing. [0004] The traditional o...

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Problems solved by technology

The former method must apply electrical signals, which increases the complexity of the system

In the latter scheme, due to the phase difference brought by the 3×3 splitter 16 itself, although a non-zero offset phase can be obtained at the interference signal output terminals 18 and 19, the offset phase is only system is not working on where the maximum linear operating range cannot be obtained

Although this structure, the equivalent phase bias, but the optical insertion loss consistency of the two output channels is very good, and it also requires circuit processing, which increases the difficulty of system implementation

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