阅读说明：本技术 评估高功率光通信系统中光纤弯曲损耗随时间变化的方法 (Method for evaluating time-dependent change of optical fiber bending loss in high-power optical communication system ) 是由 朱晓波 顾文华 桂桑 李现勤 于 2020-06-30 设计创作，主要内容包括：本发明涉及光通信技术领域,具体公开了一种评估高功率光通信系统中光纤弯曲损耗随时间变化的方法,包括以下步骤：收集高功率光通信系统的系统相关参数；根据系统相关参数,确定并输出高功率光通信系统中随时间变化的光纤截止波长；根据系统相关参数和光纤截止波长,确定并输出高功率光通信系统中随时间变化的光纤临界曲率半径；将光纤弯曲部分的目标弯曲半径与高功率光通信系统中随时间变化的光纤临界曲率半径进行比较,若光纤弯曲部分的目标弯曲半径大于光纤临界曲率半径,则忽略该光纤弯曲部分对高功率光通信系统的影响；若光纤弯曲部分的目标弯曲半径小于光纤临界曲率半径,则拉直或更换高功率光通信系统中的光纤的弯曲部分。(The invention relates to the technical field of optical communication, and particularly discloses a method for evaluating the time-dependent change of optical fiber bending loss in a high-power optical communication system, which comprises the following steps: collecting system-related parameters of a high-power optical communication system; determining and outputting the time-varying cut-off wavelength of the optical fiber in the high-power optical communication system according to the system related parameters; determining and outputting the critical curvature radius of the optical fiber which changes along with time in the high-power optical communication system according to the relevant parameters of the system and the cut-off wavelength of the optical fiber; comparing the target bending radius of the optical fiber bending part with the critical curvature radius of the optical fiber changing with time in the high-power optical communication system, and if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, neglecting the influence of the optical fiber bending part on the high-power optical communication system; if the target bend radius of the curved portion of the optical fiber is less than the critical radius of curvature of the optical fiber, the curved portion of the optical fiber in the high power optical communication system is straightened or replaced.)

1. A method for estimating the time-dependent variation of the bending loss of an optical fiber in a high-power optical communication system, comprising the steps of:

s110: collecting system-related parameters of the high-power optical communication system; the system related parameters comprise the fiber core radius of the optical fiber, the fiber core refractive index, the cladding refractive index, the relative refractive index of the optical fiber, the working wavelength of the optical fiber, and the target bending radius and the number of bending turns of the bent part of the optical fiber;

s120: determining and outputting a time-varying fiber cut-off wavelength in the high-power optical communication system according to the system-related parameters;

s130: determining and outputting the critical curvature radius of the optical fiber which changes along with time in the high-power optical communication system according to the system-related parameters and the cut-off wavelength of the optical fiber;

s140: comparing the target bending radius of the optical fiber bending part with the critical curvature radius of the optical fiber changing with time in the high-power optical communication system, and if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, neglecting the influence of the optical fiber bending part on the high-power optical communication system; and if the target bending radius of the optical fiber bending part is smaller than the critical curvature radius of the optical fiber, straightening or replacing the bending part of the optical fiber in the high-power optical communication system.

2. The method of claim 1, wherein the step of comparing the target bending radius of the bent portion of the optical fiber with the critical curvature radius of the optical fiber in the high power optical communication system is performed in S140;

if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, obtaining a model of the time variation of the critical curvature radius of the optical fiber;

and calculating the time required for the target bending radius of the bent part of the optical fiber to be smaller than the critical curvature radius according to the model, and prejudging the normal working time limit of the high-power optical communication system.

3. The method for evaluating the time-dependent change of the bending loss of the optical fiber in the high-power optical communication system according to claim 1, wherein the calculation formula of the cut-off wavelength of the optical fiber is as follows:

wherein λ c is the fiber cut-off wavelength, t is the high power laser turn-on time, L is the crack width equivalent to the damage of the high power laser to the fiber, η is the thermal damage coefficient, R is the fiber bending radius, m is the fiber bending turn number, a is the fiber core radius, △ is the fiber relative refractive index, n is the fiber bend turn number_coreIs the core refractive index, n_airIs the refractive index of air.

4. The method for evaluating the time variation of the bending loss of the optical fiber in the high power optical communication system according to claim 3, wherein the calculation formula of the critical curvature radius of the optical fiber is as follows:

wherein Rc is the critical curvature radius of the optical fiber, λ is the working wavelength of the optical fiber, and Δ n is the refractive index difference of the cladding of the fiber core.

Technical Field

The invention relates to the technical field of optical communication, in particular to a method for evaluating the time-dependent change of optical fiber bending loss in a high-power optical communication system.

Background

Currently, the emerging 5G technology is actively developing, and the optical fiber communication transmission system is developing towards higher transmission power, larger transmission capacity and longer transmission distance. In the actual routing process of a communication system, optical fibers are inevitably bent, especially at the optical fiber connection position and the like, and for a common G652 type optical fiber, the critical curvature radius is 15mm, namely when the bending radius is lower than 15mm, the loss caused by the optical fiber transmission system cannot be ignored. Furthermore, in a transmission system, the bending loss of the optical fiber under the continuous influence of the high-power laser light can be amplified, which has a great influence on our high-power long-distance optical communication system. For high-power optical communication systems used for a long time, the bending loss of the optical fiber is gradually increased along with the use time, which brings a lot of troubles to the optical communication system. At present, the forming mechanism and theoretical calculation formula of the bending loss (macrobending loss) and microbending loss of the optical fiber and the experimental measurement method have a lot of research and reference. The mechanism of fiber damage during high power laser injection and the measures for improving the laser damage resistance of the fiber have been studied by many people. However, the influence of high-power laser on the bending loss of the optical fiber is rarely studied in the prior art.

Disclosure of Invention

The invention provides a method for evaluating the change of optical fiber bending loss along with time in a high-power optical communication system, which aims to solve the problem that the optical fiber bending loss can be amplified in the high-power optical communication system in the prior art, so that the high-power optical communication system is greatly influenced.

As a first aspect of the present invention, there is provided a method of evaluating a change with time of a bending loss of an optical fiber in a high power optical communication system, comprising the steps of:

s110: collecting system-related parameters of the high-power optical communication system; the system related parameters comprise the fiber core radius of the optical fiber, the fiber core refractive index, the cladding refractive index, the relative refractive index of the optical fiber, the working wavelength of the optical fiber, and the target bending radius and the number of bending turns of the bent part of the optical fiber;

s120: determining and outputting a time-varying fiber cut-off wavelength in the high-power optical communication system according to the system-related parameters;

s130: determining and outputting the critical curvature radius of the optical fiber which changes along with time in the high-power optical communication system according to the system-related parameters and the cut-off wavelength of the optical fiber;

s140: comparing the target bending radius of the optical fiber bending part with the critical curvature radius of the optical fiber changing with time in the high-power optical communication system, and if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, neglecting the influence of the optical fiber bending part on the high-power optical communication system; and if the target bending radius of the optical fiber bending part is smaller than the critical curvature radius of the optical fiber, straightening or replacing the bending part of the optical fiber in the high-power optical communication system.

Further, the step of comparing the target bending radius of the optical fiber bending part with the critical curvature radius of the optical fiber changing with time in the high-power optical communication system in S140;

if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, obtaining a model of the time variation of the critical curvature radius of the optical fiber;

and calculating the time required for the target bending radius of the bent part of the optical fiber to be smaller than the critical curvature radius according to the model, and prejudging the normal working time limit of the high-power optical communication system.

Further, the calculation formula of the fiber cut-off wavelength is as follows:

wherein λ c is the fiber cut-off wavelength, t is the high power laser turn-on time, L is the crack width equivalent to the damage of the high power laser to the fiber, η is the thermal damage coefficient, R is the fiber bending radius, m is the fiber bending turn number, a is the fiber core radius, △ is the fiber relative refractive index, n is the fiber bend turn number_coreIs the core refractive index, n_airIs the refractive index of air.

Further, the calculation formula of the critical curvature radius of the optical fiber is as follows:

wherein Rc is the critical curvature radius of the optical fiber, λ is the working wavelength of the optical fiber, and Δ n is the refractive index difference of the cladding of the fiber core.

The method for evaluating the change of the optical fiber bending loss along with time in the high-power optical communication system can reduce the influence of the optical fiber bending loss on the high-power optical communication system.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

Fig. 1 is a schematic flow chart illustrating a method for evaluating a change in bending loss of an optical fiber with time in a high power optical communication system according to the present invention.

FIG. 2 is a graph showing the variation of the cut-off wavelength of the optical fiber according to the present invention.

FIG. 3 is a graph showing the variation of the critical radius of curvature of an optical fiber according to the present invention.

Detailed Description

To further illustrate the technical means and effects of the present invention adopted to achieve the predetermined objects, the following detailed description will be given to the method for evaluating the time-dependent change of the bending loss of the optical fiber in the high-power optical communication system, its specific implementation, structure, features and effects thereof according to the present invention with reference to the accompanying drawings and preferred embodiments. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

In the present embodiment, a method for evaluating the time-dependent change of the bending loss of an optical fiber in a high-power optical communication system is provided, as shown in fig. 1, comprising the following steps:

s110: collecting system-related parameters of the high-power optical communication system; the system related parameters comprise the fiber core radius of the optical fiber, the fiber core refractive index, the cladding refractive index, the relative refractive index of the optical fiber, the working wavelength of the optical fiber, and the target bending radius and the number of bending turns of the bent part of the optical fiber;

s120: determining and outputting a time-varying fiber cut-off wavelength in the high-power optical communication system according to the system-related parameters;

s130: determining and outputting the critical curvature radius of the optical fiber which changes along with time in the high-power optical communication system according to the system-related parameters and the cut-off wavelength of the optical fiber;

s140: comparing the target bending radius of the optical fiber bending part with the critical curvature radius of the optical fiber changing with time in the high-power optical communication system, and if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, neglecting the influence of the optical fiber bending part on the high-power optical communication system; and if the target bending radius of the optical fiber bending part is smaller than the critical curvature radius of the optical fiber, straightening or replacing the bending part of the optical fiber in the high-power optical communication system.

Preferably, the step of comparing the target bending radius of the bent portion of the optical fiber with the critical curvature radius of the optical fiber in the high-power optical communication system with time variation in S140;

if the target bending radius of the optical fiber bending part is larger than the critical curvature radius of the optical fiber, obtaining a model of the time variation of the critical curvature radius of the optical fiber;

and calculating the time required for the target bending radius of the bent part of the optical fiber to be smaller than the critical curvature radius according to the model, and prejudging the normal working time limit of the high-power optical communication system.

Specifically, according to the obtained model of the time-varying critical curvature radius of the bent optical fiber, if the bending radius of the bent portion existing in the known system is larger than the critical curvature radius at this time, it can be determined according to the model how long time has elapsed, the bending radius will start to be smaller than the critical curvature radius, the bending loss at this time cannot be ignored, and the bent portion needs to be processed, so that the time limit of the normal operation of the system is pre-determined.

If the fiber bend radius at this point is less than the critical radius of curvature, it is said that the loss from the bend is not negligible, and the bend at that point in the system needs to be straightened or replaced.

If the bending radius of the optical fiber is larger than the critical curvature radius, the bending part can be ignored and does not bring great influence to the system; however, we can obtain from the model how long the fiber bend radius will begin to be less than the critical radius of curvature, i.e. the time period during which the system will operate properly without being affected by fiber bend loss, and thus we can obtain how long the bend needs to be processed.

Preferably, the calculation formula of the fiber cutoff wavelength is as follows:

wherein, lambada c is the cut-off wavelength of the optical fiber, t is the on-time of the high-power laser, L is the crack width equivalent to the damage of the high-power laser to the optical fiber, η is the thermal damage coefficient for describing the relation between the crack width equivalent to the damage of the high-power laser to the optical fiber and the time, R is the bending radius of the optical fiber, and m is the bending radius of the optical fiberThe number of bending turns of the optical fiber, a is the radius of the fiber core, △ is the relative refractive index of the optical fiber, n_coreIs the core refractive index; n is_airIs the refractive index of air.

Preferably, the calculation formula of the critical curvature radius of the optical fiber is as follows:

wherein Rc is the critical curvature radius of the optical fiber, λ is the working wavelength of the optical fiber, and Δ n is the refractive index difference of the cladding of the fiber core.

When the bending radius of the bent part of the optical fiber is larger than the critical curvature radius R_cAt the moment, the bending loss of the optical fiber is extremely small and can be ignored; when the bending radius of the bent part of the optical fiber is smaller than the critical curvature radius R_cAt this time, the fiber bending loss increases rapidly and cannot be ignored.