CN108152879B - A kind of multi-core fiber with controllable crosstalk - Google Patents

Abstract

The invention discloses kinds of crosstalk-controllable multi-core optical fibers, which comprise a plurality of fiber core parts, a common cladding part and a coating part, and are characterized in that the fiber core parts comprise a pump optical fiber core and a transmission optical fiber core, the diameter of the pump optical fiber core is larger than that of the transmission optical fiber core, the position distribution of the pump optical fiber core and the transmission optical fiber core is asymmetric, the transmission optical fiber core comprises at least two transmission optical fiber cores, and the crosstalk of the multi-core optical fibers can be linearly regulated.

Description

A kind of multi-core fiber with controllable crosstalk

technical field

The invention relates to the technical field of optical sensing, in particular to a multi-core optical fiber with controllable crosstalk.

Background technique

The concept of multi-core single-mode fiber was proposed by France Telecom in 1994. France Telecom and Alcatel designed and developed four-core single-mode fiber. At the European Optical Communication Conference in 2010, the space division multiplexing (SDM) technology based on multi-core fiber and few-mode fiber was recognized as the key technology for improving the optical fiber communication system, and was recognized by the scientific research and scholars of various institutions, and was regarded as the follow-up wave. The second technological revolution of optical fiber transmission technology after division multiplexing technology. According to the retrieval, in just a few years, many batches of low-loss, low-crosstalk multi-core fibers have been designed, drawn and tested internationally, and a variety of low-loss and low-crosstalk multiplexers/demultiplexers have been produced. , and reported the corresponding transmission experiments at international conferences such as the American Optical Fiber Communication Exhibition and Conference (OFC) and the European Optical Communication Conference (ECOC).

There are two functions in the development of multi-core fibers according to the mutual proximity of the groups of cores in the multi-core fiber.

The distance between the cores of the multiple groups is relatively large, and the distance between the centers of the cores is greater than 30.0 μm, that is, the structure does not produce optical coupling. The multi-core optical fiber can significantly improve the integration density per unit area of the transmission line. For example, my country's YOFC Optical Fiber and Cable Co., Ltd., in cooperation with the optical communication and optical network engineering research team of Huazhong University of Science and Technology, took the lead in drawing a homogenous weakly coupled seven-core single-mode fiber in China. Through testing the performance parameters of fiber attenuation spectrum, cut-off wavelength, bending loss, crosstalk, dispersion, polarization mode dispersion, etc., the process is continuously optimized, and finally a seven-core fiber with low crosstalk and low loss is realized. The attenuation of this multi-core fiber at 1550nm is about 0.20dB/km, and the crosstalk is lower than -40dB/100km, which fills the technical gap in the field of special fiber in China. Many fiber optic manufacturers are close.

The distance between the cores of the multiple groups is small, and the distance between the centers of the cores is less than 30.0 μm, that is, the structure that produces the optical coupling effect. Using this principle, the industry is developing dual-core sensors or optical circuit devices. However, in the existing multi-core fiber design scheme, once the design is completed, the coupling between the fiber cores cannot be changed and controlled. This greatly limits the application of new fiber optic sensor systems using multi-core fibers, especially those that require the introduction of controllable crosstalk in different optical transmission paths, including changes in amplitude, phase, etc., such as optoelectronic oscillators, microwave photonic filters , optical delay lines, etc. At present, most of the existing multi-core fiber design schemes are dedicated to improving the integration density per unit area of the transmission line. optimization, and many schemes are less involved in the multi-core fiber design of crosstalk controllability. Therefore, it is necessary to propose a new multi-core fiber with controllable crosstalk.

SUMMARY OF THE INVENTION

In order to solve the above problems, the present invention proposes a multi-core optical fiber with controllable crosstalk, which includes a plurality of core parts, a common cladding part and a coating part, and the core parts include a pump optical fiber core and a transmission optical fiber core , the diameter of the pump fiber core is larger than the diameter of the transmission fiber core; the position distribution of the pump fiber core and the transmission fiber core is asymmetric; the transmission fiber core includes at least two transmission fiber cores; The crosstalk of the multi-core fiber can be adjusted linearly.

Preferably, the diameter of the pump fiber core is in the range of 20.0-25.0 μm.

Preferably, the transmission fiber core includes a first transmission fiber core and a second transmission fiber core, and the center distance between the first transmission fiber core and the pump fiber core is smaller than the center distance between the second transmission fiber core and the pump fiber core The center distance of the Pu fiber core.

Preferably, the diameter of the transmission fiber core is in the range of 8.0-10.0 μm.

Preferably, the center distance between the first transmission fiber core and the pump fiber core is in the range of 38.0-65.0 μm.

Preferably, the center distance between the second transmission fiber core and the pump fiber core is in the range of 68.0-95 μm.

Preferably, the center distance between the first transmission fiber core and the second transmission fiber core is in the range of 68.0-95 μm.

Preferably, the incident power of the pump fiber core and the crosstalk value of the first transmission fiber core satisfy the following linear relationship:

C=a×P-b,

Among them, C represents the crosstalk value of the first transmission fiber core, in dBm; P represents the incident power of the pump fiber core, in dBm; a is 0.69-0.79, and b is 35-40.

Preferably, the pump fiber core is used to transmit high-power pump light energy, and the transmission fiber core is used to transmit optical communication signals.

Preferably, both the pump fiber core and the transmission fiber core include a core and a cladding.

Beneficial effects of the present invention:

The invention provides a multi-core optical fiber with controllable crosstalk, which can change and control the light wave coupling effect generated between the cores by controlling the incident light power in the pump optical fiber core, so that the multi-core optical fiber has the characteristics of controllable crosstalk; The limit on the core diameter of the optical fiber core and the allowable error in the distance between adjacent cores is greatly reduced.

Description of drawings

FIG. 1 is a schematic cross-sectional view of the crosstalk-controllable multi-core optical fiber of the present invention.

2 is a dimension drawing of the diameters of various fiber cores in the crosstalk-controllable multi-core fiber of the present invention, wherein the multi-core fiber diameter D1, the pump fiber core diameter D2, and the transmission fiber core diameter D3.

Fig. 3 is a drawing of the center distance between various fiber cores in the crosstalk controllable multi-core fiber of the present invention, wherein the distance between the pump fiber core and the first transmission fiber core is L1; the pump fiber core and the first transmission fiber core are L1; The distance between the two transmission fiber cores is L2; the center distance between the two transmission fiber cores of the first transmission fiber core and the second transmission fiber core is L3.

4 is a graph showing the corresponding relationship between the incident optical power in the pump fiber core and the crosstalk in the transmission fiber core of the present invention, wherein “triangle” represents the crosstalk in the first transmission fiber core that is closer to the pump fiber core, and the solid line represents its fitting curve; "circle" represents the crosstalk in the second transmission fiber core farther from the pump fiber core, and the dashed line represents its fitting curve.

Detailed ways

The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings. The present application can be implemented in many different forms, and is not limited to the implementation described in this embodiment. The following specific embodiments are provided for the purpose of facilitating a clearer and more thorough understanding of the content of the present invention, wherein the words indicating orientation, such as up, down, left and right, are only for the positions of the structures shown in the corresponding drawings.

Example 1

1 to 4 , the present invention proposes a multi-core optical fiber with controllable crosstalk, the multi-core optical fiber includes a plurality of core parts, a common cladding part 1 and a coating part, wherein the core parts include different sizes The pump fiber core 2 and the transmission fiber core, the pump fiber core 2 is used to transmit high-power pump light energy, and the transmission fiber core is used to transmit optical communication signals; both the pump fiber core 2 and the transmission fiber core include the core and The cladding portion extends along the central axis of the multi-core fiber; the common cladding portion holds the core portion integrally inside it in a state where the pump fiber core 2 and the transmission fiber core are spaced apart from each other.

Specifically, the multi-core fiber of the present invention includes a pump fiber core 2 and a transmission fiber core, wherein the core diameters of the two fiber cores are different, and the positional arrangement and distribution of the two fiber cores are asymmetrical, roughly triangular; The diameter D2 of the optical fiber core 2 is in the range of 20.0-25.0 μm, and the diameter D3 of the transmission optical fiber core is in the range of 8.0-10.0 μm; the transmission optical fiber core includes at least two.

The transmission fiber core includes a first transmission fiber core 3 and a second transmission fiber core 4. The first transmission fiber core 3 is closer to the pump fiber core 2 than the second transmission fiber core 4. Further, the first transmission fiber core 3 is connected to the pump fiber core 2. The center distance L1 of the optical fiber core 2 is in the range of 38.0 to 65.0 μm; the center distance L2 of the second transmission optical fiber core 4 and the pump optical fiber core 2 is in the range of 68.0 to 95.0 μm; the first transmission optical fiber core 3 and the second transmission The center distance L3 of the optical fiber core 4 is in the range of 68.0 to 95.0 μm.

In this embodiment, the diameter D1 of the multi-core fiber is preferably 125.0 μm, wherein the diameter of the pump fiber core 2 is 20.0 μm; the diameters of the first transmission fiber core 3 and the second transmission fiber core 4 are equal to 8.0 μm; the center-to-center distance L1 between the pump fiber core 2 and the first transmission fiber core 3 in the multi-core fiber is 38.0 μm; the center-to-center distance L2 between the pump fiber core 2 and the second transmission fiber core 4 is 78.0 μm; the first The center distance L3 of the transmission fiber core 3 and the second transmission fiber core 4 is 78.0 μm.

In order to verify that by controlling the incident light power in the pump fiber core, the multi-core fiber of the present invention can generate tunable light wave coupling and has the characteristics of controllable crosstalk, the following experiments were carried out.

Prepare multi-core fiber A, multi-core fiber B, multi-core fiber C, multi-core fiber D, multi-core fiber E, multi-core fiber F, and multi-core fiber G (the specific dimensions are as follows, in which the diameter D1 of the multi-core fiber is 125.0 μm), by adjusting the output power of the pump laser, gradually increase the incident light power in the pump fiber core from 0 to 35dBm, and measure the crosstalk value of each transmission fiber core.

The measurement shows that the crosstalk in the range of -40dB/100km～-12dB/100km is obtained in the first transmission fiber core that is closer to the pump fiber core, and the change is approximately linear, while the distance from the pump fiber core is farther away. In the second transmission fiber core of , the crosstalk has no obvious change and is maintained at about -40dB/100km. See Figure 4 for details.

According to the measured values, the incident power of the pump fiber core and the crosstalk value of the first transmission fiber core satisfy the following linear relationship:

C=a×P-b,

Among them, C represents the crosstalk value of the first transmission fiber core, in dBm; P represents the incident power of the pump fiber core, in dBm; a is 0.69-0.79, and b is 35-40.

It can be seen from this that the crosstalk difference between the first transmission fiber core and the second transmission fiber core can be linearly tuned by changing the incident light power in the pump fiber core. Therefore, the multi-core optical fiber of the present invention can generate tunable light wave coupling and has the characteristics of controllable crosstalk.

It should be noted that the multi-core optical fiber of the present invention is suitable for the preparation of new optical fiber sensors in the fields of national defense, industrial production and civil use, especially those systems that need to introduce controllable crosstalk on different optical transmission paths, including changes in amplitude, phase, etc. applications, such as optoelectronic oscillators, microwave photonic filters, optical delay lines, etc.

The above description is only a preferred embodiment of the patent of the present invention, but the protection scope of the patent of the present invention is not limited to this. The changes or substitutions should be covered within the protection scope of the patent of the present invention.

Claims (7)

1. A multi-core optical fiber includes a plurality of core portions, a common cladding portion and a coating portion, wherein the core portions include a pump optical fiber core and a transmission optical fiber core, the diameter of the pump optical fiber core is larger than that of the transmission optical fiber core, the positions of the pump optical fiber core and the transmission optical fiber core are asymmetrically distributed, the transmission optical fiber core includes at least two transmission optical fiber cores, crosstalk of the multi-core optical fiber can be linearly controlled, wherein,

   the diameter of the pump optical fiber core is within the range of 20.0-25.0 μm;

   the transmission fiber core comprises th transmission fiber core and a second transmission fiber core, the th transmission fiber core is closer to the center of the pump fiber core than the second transmission fiber core is to the center of the pump fiber core;

   the incident power of the pump fiber core and the crosstalk value of the th transmission fiber core satisfy the following linear relation:

   C＝a×P-b，

   wherein C represents the crosstalk value of the th transmission optical fiber core in dBm, P represents the incident power of the pump optical fiber core in dBm, a is 0.69-0.79, and b is 35-40.
2. 2. The multicore optical fiber of claim 1, wherein the transmission fiber core has a diameter in the range of 8.0 to 10.0 μm.
3. 3. The multicore optical fiber of claim 1, wherein the th transmission fiber core is located at a center distance of 38.0 μm to 65.0 μm from the pump fiber core.
4. 4. The multi-core optical fiber as claimed in claim 1, wherein the second transmission fiber core is located at a center distance from the pump fiber core in a range of 68.0 μm to 95 μm.
5. 5. The multicore optical fiber of claim 2, wherein the th transmission fiber core is located at a center distance from the second transmission fiber core in the range of 68.0 μm to 95 μm.
6. 6. The multi-core optical fiber as claimed in claim 1, wherein the pump fiber core is configured to transmit high power pump light energy and the transmission fiber core is configured to transmit optical communication signals.
7. 7. The multicore optical fiber of claim 1, wherein the pump optical fiber core and the transmission optical fiber core each comprise a core and a cladding.

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