CN2876808Y - Optical fiber raster tubular temp. compensation packaging structure - Google Patents

Abstract

An optical fiber raster tubular temperature compensation packaging structure comprises an inner sleeve and an outer sleeve with small expansion coefficients and a connecting tube with large expansion coefficient, wherein, the connecting tube with large expansion coefficient is arranged between the inner sleeve and the outer sleeve, and a raster is bonded to at both sides of the inner sleeve and the outer sleeve; in the course of application, when the temperature rises, the inner part of the packaging structure deforms, and the stress fluctuation of the optical fiber decreases. At this moment, the moving direction of the drift Delta Lambda s arising from the stress fluctuation is opposite to the moving direction of the drift Delta Lambda T arising from the temperature increase. Through appropriate design, the moving ranges can be made equal, thus maintaining stable wavelength in the center of the raster. The utility model provides a miniaturized optical fiber raster tubular temperature compensation packaging structure which is simple in structure and easy to package.

Description

Fiber grating tubulose temperature compensation encapsulating structure

Technical field

The utility model relates to a kind of technology that fiber grating is carried out the passive encapsulation of temperature compensation, belongs to the technical field of fiber grating encapsulation.

Background technology

Fiber grating is a kind ofly to utilize ultraviolet light that the optical fiber with light sensitive characteristic is exposed and form a kind of new optical devices that refractive index cycle changes in the fiber cores district.

Because the variation of environment temperature can make fiber lengths and fiber core refractive index change, and then causes the drift of grating centre wavelength, and grating centre wavelength is an important parameter of grating.

Over the past two years, fiber grating was progressively carried out in the application in fields such as communication, optics, electronics, sensing, especially increased rapidly at sensory field, progressively reached practicability.Yet need overcome above-describedly because how the grating centre wavelength drift that temperature variation causes makes grating wavelength constant on the wavelength of appointment in many fields that fiber grating is used, be the problem that presses for solution in the industry.

For the centre wavelength that makes grating does not change with temperature, need carry out necessary encapsulation to grating, total packaged type be divided into active encapsulation and passive encapsulation two big classes.

Active encapsulation adds temperature control system usually in the grating enclosure, thereby the constant purpose that reaches stationary raster centre wavelength of the environment temperature that makes the grating place, this active encapsulation is because the temperature control system that need add in addition, therefore, make encapsulating structure become complicated, and the packaging cost height is unfavorable for the product miniaturization.

Passive encapsulation then is to realize that by special material or structure centre wavelength is stable.The implementation method of passive encapsulation mainly contains following several at present:

1, negative expansion material package technology: this method is that grating is sticked on the special negative expansion material, and when temperature rose, the stress that material contracts discharged came the drift of null grating centre wavelength.

2, two material structure encapsulation technologies: this method is that grating is sticked on special two material structures, produces owing to the expansion coefficient of two kinds of materials is inconsistent and is similar to the negative expansion characteristic, discharges the drift that stress comes null grating centre wavelength when temperature rises.Thereby realize the hot insensitivity of grating centre wavelength.

3, adiabatic encapsulation technology: this method is that grating is encapsulated in the material of porous or vacuum interlayer, uses adiabatic method to realize that grating centre wavelength is to hot insensitivity.

At present, the technology of above-mentioned passive encapsulation exists equally that structure is complicated, packaging cost is higher, is unfavorable for problems such as product miniaturization.

The utility model content

The purpose of this utility model is in order to address the above problem, a kind of fiber grating tubulose temperature compensation encapsulating structure of miniaturization of simple in structure, easy encapsulation is provided, and is the encapsulating structure of a kind of improved pair of material tubulose passive temperature compensation on the basis of existing two material structure schemes.

The purpose of this utility model is achieved in that

A kind of fiber grating tubulose temperature compensation encapsulating structure, it comprises: being provided with expansion coefficient in the outside of described grating is α ₂The inner sleeve made of material, the length of described inner sleeve is L ₂The length that begins from an end of described inner sleeve is L ₃To be provided with expansion coefficient be α in the outside ₂The outer tube made of material, making described inner sleeve and described outer tube that length be arranged is L ₃Part be the part that is nested together, described outer tube length is L ₁, and satisfy: L ₁＞L ₃The two ends of described grating are bonded in respectively on the two ends that are not nested together in the described inside and outside sleeve pipe, and these two ends also are described optical fiber and described inside and outside sleeve pipe viscose glue tie point; At described inner sleeve and described outer tube length being arranged is L ₃The part that is nested together between to be equipped with length be L ₃Connecting pipe, described connecting pipe is connected with described inside and outside sleeve pipe with internal and external casing viscose glue tie point by connecting pipe respectively, described connecting pipe is α by temperature expansion coefficient ₂Material make, and satisfy: α ₂＞α ₁Described inner sleeve length L ₂, the outer tube length L ₁, the connecting pipe length L ₃In time, satisfy: L _f=L ₁+ L ₂-L ₃, described L _fTotal length for the package tube after described grating and the described fiber package.

Effect of the present utility model:

Fiber grating tubulose temperature compensation encapsulating structure of the present utility model has the following advantages and effect:

(1) can realize tubulose miniaturization encapsulation, easier being employed;

(2) encapsulation is easy, and temperature parameter is controlled easily;

(3) temperature compensation performance is good, reaches practical index.

For further specifying above-mentioned purpose of the present utility model, design feature and effect, the utility model is described in detail below with reference to accompanying drawing.

Description of drawings

Fig. 1 is the detailed section view of the utility model structure:

Fig. 2 is the wiring layout of the utility model structure:

Fig. 3 is with the temperature variant comparison diagram of grating centre wavelength after the utility model construction packages.

The explanation of the symbol of critical piece in the accompanying drawing:

1---outer tube;

2---inner sleeve;

3---connecting pipe

4,4 '---connecting pipe and internal and external casing viscose glue tie point;

5,5 '---optical fiber and inside and outside sleeve pipe viscose glue tie point;

6---optical fiber;

7---grating;

8---protection tube;

Specific implementation method

Be elaborated below in conjunction with the embodiment of accompanying drawing to fiber grating tubulose temperature compensation encapsulating structure of the present invention.

Principle of work of the present utility model is based on temperature variation and the STRESS VARIATION common influence to the centre wavelength of fiber grating, promptly utilizes the STRESS VARIATION that presets to come the influence of compensation temperature to the centre wavelength of fiber grating.

In addition, structure of the present utility model has been introduced multilayer sleeve structure, is made up of internal and external casing and the big connecting pipe of expansion coefficient that expansion coefficient is little; Connecting pipe connects internal and external casing with viscose glue, and fiber grating is fixed on the two ends of internal and external casing with viscose glue, and the size of internal and external casing and connecting pipe is calculated by corresponding formulas and provided.

When the utility model encapsulates fiber grating, optical fiber tension generation prestress is changed.In the use afterwards, when temperature rises, the inner generation of encapsulating structure deformation, the suffered STRESS VARIATION of optical fiber reduces, this moment, the moving direction of the drift delta λ S that causes of STRESS VARIATION was then opposite with the rise drift direction of the Δ λ T that causes of temperature, by suitable design, the amplitude that can move it equates, thereby has kept the stable of grating centre wavelength.

Referring to accompanying drawing, Fig. 1 is that the detailed section view of the utility model structure: Fig. 2 is the wiring layout of the utility model structure.

Fiber grating tubulose temperature compensation encapsulating structure of the present utility model is by forming with the lower part.

Being provided with expansion coefficient in the outside of grating 7 is α ₂The inner sleeve 2 made of material, the length of described inner sleeve 2 is L ₂

The length that begins from an end of described inner sleeve 2 is L ₃To be provided with expansion coefficient be α in the outside ₂The outer tube 1 made of material, making described inner sleeve 2 with described outer tube 1 length be arranged is L ₃Part be the part that is nested together, described outer tube 1 length is L ₁, and satisfy L ₁＞L ₃

Inside and outside sleeve pipe 2,1 is used metal tube in the present embodiment.

The two ends of described grating 7 be bonded in respectively the two ends 5,5 that are not nested together in the inside and outside sleeve pipe 2,1 ' on, that is, and these two ends also be optical fiber and inside and outside sleeve pipe viscose glue tie point 5,5 '.

With described outer tube 1 length being arranged at described inner sleeve 2 is L ₃The part that is nested together between to be equipped with length be L ₃Connecting pipe 3, described connecting pipe 3 is respectively by connecting pipe and internal and external casing viscose glue tie point 4,4 ' be connected with described inside and outside sleeve pipe 2,1.Described connecting pipe 3 is α by temperature expansion coefficient ₂Material make, and satisfy α ₂＞α ₁Connecting pipe 3 is a metal tube in the present embodiment, and the shape of connecting pipe 3 is " Z " types.

Outside at described inside and outside sleeve pipe 2,1 is covered with protection tube 8.

In sum, the utility model is made up of the little inner sleeve 2 of expansion coefficient, outer tube 1 and the big connecting pipe 3 of expansion coefficient.The two ends that grating 7 is bonded in inside and outside sleeve pipe 2,1 form.As shown in Figure 1, L ₁And L ₂Be temperature expansion coefficient (α ₁) the lower outer tube 2 and the length of inner sleeve 1, L ₃Be temperature expansion coefficient (α ₂) length of higher metal connecting tube 3, that is, their expansion coefficient CTE (Coefficient ofThermal Expansion) is respectively α ₁And α ₂, L _fIt is the length overall of the package tube after the encapsulation.Total length L by package tube when temperature raises _fCome compensate for temperature effects.When grating 7 centre wavelengths are λ, need control temperature drift wavelength amount during grating 7 temperature rising Δ T is Δ λ, and the grating pre-tensile stress is changed to ε 1, then has when temperature rising Δ T:

$\frac{\mathrm{\Δ\λ}}{\mathrm{\λ}}{=K}_1\mathrm{\ΔT}+K_2\mathrm{\Δ\ϵ}---\left(1\right)$

Wherein: K ₁=α+ξ ≈ 6.81 * 10 ^-6Be the temperature coefficient of grating, K ₂=(1-P _e) ≈ 0.78 is the STRESS VARIATION coefficient of grating.

When temperature rising Δ T, each length of tube variable quantity is: Δ L ₁=α ₁L ₁Δ T, Δ L ₂=α ₁L ₂Δ T, Δ L ₃=α ₂L ₃Δ T, then Δ L _f=Δ L ₁+ Δ L ₂-Δ L ₃=(α ₁L ₁+ α ₁L ₂-α ₂L ₃) Δ T

STRESS VARIATION ε 2 on the fiber grating is at this moment:

${\mathrm{\ϵ}}_2={\mathrm{\ϵ}}_1+\frac{\mathrm{\Δ}{L}_f}{L_f}-\mathrm{\α\ΔT}---\left(2\right)$

Ignore grating expansion item, the STRESS VARIATION changes delta ε that gets grating is:

$\mathrm{\Δ\ϵ}=\frac{\mathrm{\Δ}{L}_f}{L_f}=\left(\frac{{\mathrm{\α}}_1{L}_1+{\mathrm{\α}}_1{L}_2-{\mathrm{\α}}_2{L}_3}{L_f}\right)\·\mathrm{\ΔT}---\left(3\right)$

Bringing formula (1) into gets:

$\frac{\mathrm{\Δ\λ}}{\mathrm{\λ}}=K_1\mathrm{\ΔT}+K_2\left(\frac{{\mathrm{\α}}_1{L}_1+{\mathrm{\α}}_1{L}_2-{\mathrm{\α}}_2{L}_3}{L_f}\right)\mathrm{\ΔT}---\left(4\right)$

Put in order:

$\left\{\begin{array}{c}{\mathrm{\α}}_1(L_1+L_2)-{\mathrm{\α}}_2\·L_3=(\frac{\mathrm{\Δ\λ}}{\mathrm{\λ}\·\mathrm{\ΔT}}-K_1)\frac{L_f}{K_2}\\ L_1+L_2-L_3=L_f\end{array}\right.---\left(5\right)$

After choosing the material of each pipe, just can draw the proportionate relationship of each length of tube by formula (5).For example, if the package tube length overall L after wishing to encapsulate _fFor about 50mm, at C-band (1525nm～1565nm) control the every degree temperature drift of grating wavelength amount less than 1pm, if inner and outer pipe 2,1 is selected with the low invar pipe of expansion coefficient, connecting pipe 3 is selected the big duralumin of expansion coefficient for use, then gets inside and outside pipe range 35.8mm according to formula (5) and connects pipe range 21.5mm; If inner and outer pipe 2,1 is selected to use the invar pipe, connecting pipe 3 is selected brass for use, then gets inside and outside pipe range 39.8mm according to formula (5) and connects pipe range 29.8mm.

Referring to Fig. 3, Fig. 3 is with the temperature variant comparison diagram of grating centre wavelength after the utility model construction packages.

X-axis is a temperature among Fig. 3, and unit is ℃; Y-axis is a wavelength, and unit is nm; The curve of band * is that the preceding centre wavelength of grating encapsulation is with the variation of temperature curve; The curve of band o is that grating encapsulation rear center wavelength is with the variation of temperature curve.

From above-mentioned grating encapsulation rear center wavelength with the variation of temperature curve as can be seen, the utility model changes optical fiber tension generation prestress owing to used when optical fiber 6 and grating 7 are encapsulated.In the use afterwards, when temperature rises, the inner generation of encapsulating structure deformation, optical fiber 6 suffered STRESS VARIATION reduce, this moment, the moving direction of the drift delta λ S that causes of STRESS VARIATION was then opposite with the rise drift direction of the Δ λ T that causes of temperature, thereby had kept the stable of grating centre wavelength.

Those of ordinary skill in the art will be appreciated that, above embodiment is used for illustrating the utility model, and be not to be used as qualification of the present utility model, as long as in connotation scope of the present utility model, all will drop in the scope of the utility model claims variation, the modification of the above embodiment.

Claims (6)

1, a kind of fiber grating tubulose temperature compensation encapsulating structure is characterized in that comprising:

Being provided with expansion coefficient in the outside of described grating is α ₂The inner sleeve made of material, the length of described inner sleeve is L ₂

The length that begins from an end of described inner sleeve is L ₃To be provided with expansion coefficient be α in the outside ₂The outer tube made of material, making described inner sleeve and described outer tube that length be arranged is L ₃Part be the part that is nested together, described outer tube length is L ₁, and satisfy: L ₁＞L ₃

The two ends of described grating are bonded in respectively on the two ends that are not nested together in the described inside and outside sleeve pipe, and these two ends also are described optical fiber and described inside and outside sleeve pipe viscose glue tie point;

At described inner sleeve and described outer tube length being arranged is L ₃The part that is nested together between to be equipped with length be L ₃Connecting pipe, described connecting pipe is connected with described inside and outside sleeve pipe with internal and external casing viscose glue tie point by connecting pipe respectively, described connecting pipe is α by temperature expansion coefficient ₂Material make, and satisfy: α ₂＞α ₁

Described inner sleeve length L ₂, the outer tube length L ₁, the connecting pipe length L ₃In time, satisfy: L _f=L ₁+ L ₂-L ₃, described L _fTotal length for the package tube after described grating and the described fiber package.

2, fiber grating tubulose temperature compensation encapsulating structure as claimed in claim 1 is characterized in that:

Described connecting pipe is a metal tube.

3, fiber grating tubulose temperature compensation encapsulating structure as claimed in claim 1 is characterized in that:

The shape of described connecting pipe is " Z " type.

4, fiber grating tubulose temperature compensation encapsulating structure as claimed in claim 1 is characterized in that:

Described inner sleeve length L ₂, the outer tube length L ₁, the connecting pipe length L ₃, package tube length overall for the degree L _f, when the centre wavelength of described grating is λ, in the time of when described grating temperature rising Δ T, need controlling temperature drift wavelength amount and be Δ λ, satisfy following formula:

$\left\{\begin{array}{c}{\mathrm{\α}}_1(L_1+L_2)-{\mathrm{\α}}_2\·L_3=(\frac{\mathrm{\Δ\λ}}{\mathrm{\λ}\·\mathrm{\ΔT}}-K_1)\frac{L_f}{K_2}\\ L_1+L_2-L_3=L_f\end{array}\right.$

K wherein ₁Be the temperature coefficient of grating, K ₂STRESS VARIATION coefficient for grating.

5, fiber grating tubulose temperature compensation encapsulating structure as claimed in claim 1 is characterized in that:

Described inside and outside sleeve pipe is a metal tube.

6, fiber grating tubulose temperature compensation encapsulating structure as claimed in claim 1 is characterized in that:

Outside at described inside and outside sleeve pipe is covered with protection tube.