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Multi-cascade fiber bragg grating filter

A fiber grating and multi-cascade technology, which is applied in the direction of cladding optical fiber, optical waveguide, light guide, etc., can solve the problems of difficult to achieve selective band filtering, the filtering effect is not very ideal, and the filtering bandwidth is not flat enough to achieve high reflection , good filtering characteristics, the effect of expanding the filtering range

Inactive Publication Date: 2010-12-15
NINGBO UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The filters produced by the above two schemes have the disadvantages of low reflectivity, flat filtering bandwidth, and difficulty in achieving selective band filtering, resulting in unsatisfactory filtering effects.

Method used

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  • Multi-cascade fiber bragg grating filter
  • Multi-cascade fiber bragg grating filter
  • Multi-cascade fiber bragg grating filter

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] A kind of multi-cascaded fiber grating filter proposed by the present invention, such as figure 1As shown, it is mainly composed of input optical fiber 81, output optical fiber 82 and multi-cascaded fiber grating 83. The ends are connected, the tail end of the multi-cascade fiber grating 83 is connected with the first end of the output fiber 82, the second end of the output fiber 82 outputs the signal light source, and the multi-cascade fiber grating 83 is mainly composed of M optical fibers with different central periods Grating groups 1, 2, ..., I, ..., M are composed of end-to-end series connections, each fiber grating group is mainly composed of m unit gratings with the same central period connected in series, for example, the first fiber grating group is mainly composed of m Unit gratings 11, ..., 1i, ..., 1m with the same central period are connected in series end to end, for example, the Mth fiber grating group is mainly composed of m unit gratings M1, ..., Mi, ....

Embodiment 2

[0033] This embodiment provides the filtering characteristics of a filter composed of a fiber grating group. The parameters used here are: the effective refractive index of each unit grating is 1.45, and the effective refractive index modulation depth of each unit grating is 0.0002 , the central period Λ of the fiber grating group and each unit grating constituting the fiber grating group 0 =5.338 μm, the total chirp amount C=2nm of the unit grating, the length l=4mm of the unit grating, the total number m=15 of the unit grating contained in the fiber grating group, and the length L=6cm of the fiber grating group.

[0034] The grating cross-section at the position corresponding to the same period of each unit grating can be regarded as a mirror that reflects light of the same wavelength, and two adjacent mirrors form a Fabry-Perot resonator (F-P resonator). Multiple F-P resonant cavity interference is formed in the grating filter. Since the periodic linear chirp of the unit g...

Embodiment 3

[0037] This embodiment gives the filtering characteristics of a multi-cascaded FBG filter composed of three FBG groups. In this embodiment, only the reflection spectrum characteristics of the filter are considered when the total chirp amount C changes. The parameters used in this embodiment are as follows: the effective refractive index of each unit grating is 1.48, and the effective refractive index modulation depth of each unit grating is 3.5×10 -4 , the length of the unit grating l=4mm, the central periods of the three cascaded fiber grating groups are Λ 01 = 0.531 μm, Λ 02 =0.530μm and Λ 03 =0.529 μm, the total number of unit gratings contained in each fiber grating group m=10, the total length L of the multi-cascaded fiber grating filter total =m*l*3=12cm.

[0038] When the total chirp of each unit grating C=1nm, the period of the unit grating varies with the length of the multi-cascaded fiber grating filter as Figure 4 shown. Figure 4 Among them, the fiber grating...

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Abstract

The invention discloses a multi-cascade fiber bragg grating filter. The filter mainly comprises an input optical fiber, an output optical fiber and a multi-cascade optical fiber bragg grating, wherein the first end of the input optical is connected to a signal light source, and the second end of the input optical fiber is connected with the head end of the multi-cascade optical fiber bragg grating; the tail end of the multi-cascade optical fiber bragg grating is connected with the first end of the output optical fiber, and the second end of the output optical fiber outputs a signal light source; the multi-cascade optical fiber bragg grating is mainly composed of a plurality of optical fiber braff grating groups which have different central periods and are connected in series end to end; and each optical fiber bragg grating group is mainly composed of a plurality of unit gratings which have the same central period and are connected in series end to end. The filter has the advantages that: the filter reflects wavelengths under different Bragg conditions to greatly extend the filter range; meanwhile, filter channels are distributed at equal intervals; and the filter has the characteristics of multiple channels (the number of the channels is more than 40), high density (the channel interval is less than 0.5nm), high reflection (the reflection is approximate to 100 percent), good waveband selectivity and the like, and realizes ultra-wideband tunable comb filtering.

Description

technical field [0001] The invention relates to a filter, in particular to a multi-cascaded optical fiber grating filter with high density, high reflectivity, ultra-wide bandwidth and good band selectivity. Background technique [0002] Today, when fiber-intensive wavelength division multiplexing / demultiplexing technology is very mature, various fiber gratings are used to make tunable, multi-channel fiber comb filters, and this filter is used as a fiber-intensive wavelength division multiplexing / demultiplexing The core device of the demultiplexer has played an increasingly important role, and this filter is also widely used in other optical fiber communication systems, lasers and sensors. Therefore, with the rapid development of information technology, there is an increasingly urgent demand for high-isolation, multi-channel fiber comb filters. [0003] Fiber Bragg grating is one of the most rapidly developed fiber optic passive devices in recent years. The refractive index ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G02B6/293G02B6/02
Inventor 周骏苑红伟马伟涛孙永堂刘晓阳明仰林豪
Owner NINGBO UNIV
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