Magnetic control tunable optical fiber comb filter

Abstract

The invention relates to a magnetic control tunable optical fiber comb filter belonging to the technical fields of optical fiber sensing and optical fiber communication. The magnetic control tunable optical fiber comb filter comprises a broadband light source, an optical fiber coupler, an optical fiber environment, a magnetic field generating unit and a photoelectric detector, wherein the optical fiber environment comprises a left arm optical fiber, a right arm optical fiber and a PCFG (Photonic Crystal Fiber Grating). The magnetic control tunable optical fiber comb filter is characterized in that the PCFG cladding is provided with five large shaddock-form air holes of single-layer structures, and magnetofluid is filled into the large air holes through a capillary phenomenon and changes in the refraction index under the action of a variable magnetic field to change the effective refraction index of a PCFG cladding and cause the wavelength movement of a harmonic peak coupled between a PCFG base mode and a cladding mode so as to realize the tunability as the output characteristics of the filter. Because of different lengths of the left arm optical fiber and the right arm optical fiber in the optical fiber environment, two paths of light signals reflected by the PCFG have a light path difference and are subjected to interferences when returning to the optical fiber coupler so that a comb filter effect is generated in an output spectrum of the filter.

Description

technical field [0001] The invention relates to an optical fiber filter, which belongs to the technical fields of optical fiber sensing and optical fiber communication. Background technique [0002] Optical fiber filter is one of the basic key components in wavelength division multiplexing optical communication system and sensing system. Using the wavelength selection characteristics of fiber filters, laser mode selection can be carried out to develop fiber lasers; multi-wavelength signal wavelength division multiplexing can be realized through multiple channels; filtering can also be performed to extract useful sensor signals, etc. For example (Di Junan, Zhou Yingwu, Research on the Characteristics of a New Type of Narrow Linewidth Optical Fiber Filter, Journal of Fujian Institute of Technology, 8, 2010) proposed a high birefringence optical fiber ring nested in a Sagnac ring mirror Narrow linewidth optical fiber filter realizes narrow bandwidth filtering characteristics i...

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Problems solved by technology

However, once the filter structure of the above method is designed, the filtering characteristics are fixed, which limits its application range and is inflexible.

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