CN102074882A - Fiber bragg grating center wavelength wide range tuning device - Google Patents

Abstract

The invention relates to a fiber bragg grating (FBG) center wavelength wide range tuning device. The device comprises a bottom plate, a fixed column, a triangular bracket and a positioning block, wherein the fixed column is arranged on the bottom plate; the triangular bracket comprises a left arm and a right arm of which the top parts are rotatably connected with the fixed column; a gap is reserved between the bottom edges of the left arm and the right arm and is used for placing an FBG; optical fibers led out from the two ends of the FBG are respectively penetrated from the two ends of the left arm and the right arm; the positioning block is arranged between the left arm and the right arm and is connected with the bottom plate through a pillar; a strip-shaped piezoelectric ceramic is arranged at the top of the positioning block; and the two ends of the piezoelectric ceramic are bonded to the left arm and the right arm. Multiplied deformation can be introduced to the FBG when the piezoelectric ceramic generates a small deformation when an applied voltage is low by changing the position of a conventional piezoelectric ceramics, so that the applied voltage required by the piezoelectric ceramic is low when the FBG center wavelength wide range tuning is required. The device also has the characteristics of simple structure, low working voltage, wide wavelength tuning range, and high tuning sensitivity.

Description

Fiber grating centre wavelength wide region tuner

Technical field

The present invention relates to a kind of fiber grating centre wavelength tuner, be mainly used in FBG reflected wave centre wavelength wide region, highly sensitive tuning.

Background technology

FBG is a kind of fiber optic passive device, and it is a light sensitivity of utilizing fiber optic materials, by the method for ultraviolet photoetching, forms the space phase grating in fibre core, its essence is the filter or the speculum that form an arrowband in fibre core.Along with ultraviolet writes the perfect day by day of FBG manufacturing technology, FBG has obtained developing rapidly in the application of numerous areas, especially at fiber optic communication field.According to modulation of various different refractivities and the spectral characteristic of FBG, FBG can be applied to filter, dispersion compensator, demodulation multiplexer, router and fiber laser etc. up and down in fiber optic communication field.

Usually under the state, FBG is to preestablish fixed wave length when being applied to above-mentioned device, and this makes its application flexibility be subjected to very big restriction.If adopt tunable FBG just can address this problem preferably.For example, in filter, the tuning wavelength optical signals of can selecting by FBG leaches; In dispersion compensator, can compensate the different dispersion measures and the dispersion measure of different wave length by tuning; In fiber laser, can make laser output different wavelength of laser or the like by tuning.Therefore, still during the optical sensor system application, wish that all FBG reflected wave centre wavelength is variable, so the research of the tunable technology of FBG becomes a big focus of the application technical research of FBG no matter be optical communication system.

Realize that at present tunable FBG method is existing multiple, as: thermal tuning method, cantilever beam tuning method, piezoelectric ceramic (PZT) tuning method, electric tuning method or the like.Thereby these methods all influence the FBG geometric parameter causes the Bragg wavelength change.Based on piezoelectric effect, make piezoelectric ceramic under the applied voltage effect, produce deformation, thereby make the FBG that is fixed on the piezoelectric ceramic that deformation take place, simple in structure, be to be easy to most in the said method realize.But in the practical application,, under the condition of piezoelectric ceramic stretching tuning rate,, need add the voltage of 1000V if will reach the tuning amount of 15nm less than 2.4nm/100V for the FBG about the wavelength 1550nm of Prague (bragg).As seen, the piezoelectric ceramic tuning method needs very high voltage can satisfy general application demand.

Therefore, how under the condition of fairly simple manufacturing process and lower manufacturing cost, method to the tuning FBG of existing piezoelectric ceramic is improved, and designs to be operated under the low voltage tuningly to FBG centre wavelength wide region, just becomes the general objective in the FBG application.

Summary of the invention

The technical problem to be solved in the present invention is the tuning existing weak point of above-mentioned traditional piezoelectric ceramic, has proposed a kind of can the realization the tuning tuner of FBG wavelength wide region.

For solving the problems of the technologies described above, the present invention is based on a similar leg-of-mutton structure that can form around the both arms that fixed leg rotates, utilize lever principle, make can produce little piezoelectric ceramic deformation big FBG and elongate, thereby form the wavelength tuning of wide region.

The present invention specifically can adopt following two kinds of technical schemes:

Technical scheme one:

A kind of fiber grating centre wavelength wide region tuner comprises:

Base plate is arranged on the fixed leg on the base plate;

Triangular supports comprises left arm and right arm that top and fixed leg are rotationally connected, and leaving certain gaps uncovered by the economic plan between the base of left arm and right arm is used to place fiber grating, and the double-end optical fiber of fiber grating passes from the two ends of left arm and right arm respectively;

Locating piece is arranged between left arm and the right arm, and links to each other with base plate by pillar, and its top is provided with the bar shaped piezoelectric ceramic, and the two ends of piezoelectric ceramic and left and right arms are fitted.

For ease of fixing piezoelectric ceramic, the centre at above-mentioned locating piece top is provided with the qualification groove, and this qualification groove is used to install the bar shaped piezoelectric ceramic on the one hand, is used to limit the bar shaped piezoelectric ceramic on the other hand and is powering up moving up and down under the pulled out condition.

For piezoelectric ceramic can be fitted by the inwall with left arm triangular supports and right arm maximum area, thereby the extension of piezoelectric ceramic is farthest acted on the triangular supports, the shape of piezoelectric ceramic adopts trapezoidal.

Technical scheme two:

A kind of fiber grating centre wavelength wide region tuner comprises:

Base plate is arranged on the fixed leg on the base plate;

Triangular supports comprises left arm and right arm that top and fixed leg are rotationally connected, and leaving certain gaps uncovered by the economic plan between the base of left arm and right arm is used to place fiber grating, and the double-end optical fiber of fiber grating passes from the two ends of left arm and right arm respectively;

Piezoelectric ceramic is enclosed within on the pillar that is fixed on base plate, between left arm and right arm, and tangent with left arm and right arm.

The operation principle of technical solution of the present invention one is:

When piezoelectric ceramic changed to Δ γ, the length that FBG is stretched was:

ΔL＝H/h·Δγ (1)

Wherein: H is the total height of support, h is the distance of piezoelectric ceramic apart from bottom apex, Δ L is the tensile elongation of FBG under the piezoelectric ceramic effect, and Δ γ is the deformation after piezoelectric ceramic powers up, here as can be seen because the deformation of triangular supports FBG is H/h times of piezoelectric ceramic.Because the stretching that piezoelectric ceramic produces is very little, we ignore because piezoelectric ceramic deformation makes the displacement that the support in the vertical direction produces here.

Evenly the foveal reflex wavelength of FBG can be expressed as:

λ _B＝2n _effΛ (2)

In the formula: Λ is the cycle of grating, n _EffEffective refractive index for optical fiber.Studies show that under the constant temperature situation, the FBG wavelength that strain causes moves and can be expressed as:

Δλ _B/λ _B＝(1-P)ε (3)

Wherein P is effective elasto-optical coefficient, and it and elasto-optical effect have light; ε is the axial strain of FBG.For silica fiber, P ≈ 0.22.For the FBG here:

ε＝ΔL/L (4)

For piezoelectric ceramic,, when applying voltage V in vertical direction, have:

$\mathrm{\Δ\γ}=d_{31}\mathrm{gE}=d_{31}g\frac{V}{\mathrm{\χ}}---\left(5\right)$

With (4), (5) formula is brought (3) formula into has:

$\mathrm{\Δ}{\mathrm{\λ}}_B/{\mathrm{\λ}}_B=(1-P)\·\frac{\mathrm{\ΔL}}{L}=0.78\frac{1}{\mathrm{Lg\χ}}\·\frac{H}{h}\·d_{31}\·V---\left(6\right)$

It more than is the analysis when adopting the strip piezoelectric ceramic at technical solution of the present invention one.Equally, the hollow cylindrical piezoelectric ceramic for technical solution of the present invention two is adopted because the value of H/h is bigger, can be similar to and thinks that this moment, piezoelectric ceramic equated along the deformation of normal orientation generation with to the tensor on the horizontal direction of support generation.

As seen, compare with the tuning FBG technology of conventional piezoelectric pottery, the invention enables the less deformation of piezoelectric ceramic to develop into big deformation to FBG by triangular supports, make when FBG is required to specify deformation, the deformation that piezoelectric ceramic is required diminishes than conventional method, the promptly corresponding voltage decreases that is added on the piezoelectric ceramic, tuning sensitivity uprises.And, cause under the equal piezoelectric ceramic deformation situation that at onesize voltage if FBG length and piezoelectric ceramic are approximate, the H/h that FBG wavelength tuning of the present invention is a conventional art is doubly.

Compared with prior art, the present invention has following technique effect:

1, this FBG tuner is based on a triangular supports and traditional piezoelectric ceramic, has simple in structure, manufacturing

The advantage that cost is low.

2, the tuning piezoelectric ceramic that is positioned over wherein that still is based on of this FBG, it is convenient that electricity is transferred.

3, only need the voltage of the tuning h/H of conventional piezoelectric pottery just can reach same wavelength tuning; And very little voltage just can produce the wavelength tuning of broad, tuning sensitivity height.

Description of drawings

Fig. 1 is the structural representation of technical solution of the present invention one.

Fig. 2 is the vertical view of Fig. 1.

Fig. 3 is the structural representation of technical solution of the present invention two.

Fig. 4 is its vertical view of Fig. 3.

Fig. 5 adds the FBG reflectance spectrum of electric tuning without piezoelectric ceramic.

Fig. 6 is the FBG reflectance spectrum after piezoelectric ceramic is tuning.

Embodiment

The present invention is further illustrated below in conjunction with drawings and Examples, and it is more obvious that purpose of the present invention and effect will become.

Embodiment 1:

As shown in Figure 1 and Figure 2, trapezoidal bar shaped piezoelectric ceramic 5 is fixed in the qualification groove that is in the locating piece 2 between triangular supports 1 left arm 1-1 and the right arm 1-2, after bar shaped piezoelectric ceramic 5 is powering up generation deformation, can make the fiber grating that is fixed on triangular supports 1 base indentation, there produce wavelength tuning.Thus, according to the principle of discussing, than traditional F BG tuner, when same voltage is added on the piezoelectric ceramic 5, FBG wavelength tuning length of the present invention is H/h times traditional (wherein H is the vertical range of fiber grating apart from the triangular supports bottom, and h is the distance of piezoelectric ceramic center apart from the triangular supports bottom).

Embodiment 1 has related parameter as follows:

Fiber grating length is 11mm, and the bragg wavelength under the free state is 1550nm; The long 15cm in triangular supports top, gap width are 11mm, highly are 40cm, and thickness is 1mm; Bar shaped piezoelectric ceramic vertical centred position is 4cm apart from distance from bottom; Piezoelectric ceramic is long to be 15mm, and thickness is 3.5mm, and tensile elongation is approximately 14 μ m under 100V voltage.

(has changed in this place, the part of black matrix)

Embodiment 2:

The primary structure of present embodiment is identical with embodiment 1, and different is piezoelectric ceramic 5 is for hollow cylindrical, and is installed on the base plate 1 by pillar 8.

After suit is fixed on piezoelectric ceramic 5 making alives on the pillar 8, deformation takes place, the same figure principle is the same, and FBG can produce wavelength shift at double.

Fig. 5 is the FBG reflectance spectrum that adds electric tuning without piezoelectric ceramic, can see that FBG reflectance spectrum centre wavelength drops on the 1550nm place.

With Fig. 1, embodiment illustrated in fig. 21 is example; When piezoelectric ceramic institute making alive was 100V, FBG reflectance spectrum centre wavelength had moved on near the 1567nm as shown in Figure 6, the centre wavelength 1550nm that compares Fig. 5 as can be known, wavelength tuning is 17nm.As seen, the tuning sensitivity of embodiment 1 is 17nm/100V, method maximum than the piezoelectric ceramic tuning wavelength of routine is no more than 2.4nm/100V, tuning sensitivity is greatly improved, also be not its limiting case this moment, can recently obtain bigger value by the H/h that changes on the support.

Claims (4)

1. fiber grating centre wavelength wide region tuner is characterized in that comprising:

Base plate (6) is arranged on the fixed leg (7) on the base plate;

Triangular supports (1), comprise left arm (1-1) and right arm (1-2) that top and fixed leg (7) are rotationally connected, leaving certain gaps uncovered by the economic plan between the base of left arm (1-1) and right arm (1-2), be used to place fiber grating (4), the double-end optical fiber of fiber grating (4) (3) passes from the two ends of left arm (1-1) and right arm (1-2) respectively;

Locating piece (2) is arranged between left arm (1-1) and the right arm (1-2), and links to each other with base plate (6) by pillar (8), and its crown center position is provided with bar shaped piezoelectric ceramic (5), and the two ends of piezoelectric ceramic (5) and left and right arms are fitted.

2. fiber grating centre wavelength wide region tuner as claimed in claim 1 is characterized in that the centre at locating piece (2) top has the qualification groove, and bar shaped piezoelectric ceramic (5) is positioned at this qualification groove.

3. fiber grating centre wavelength wide region tuner as claimed in claim 1 is characterized in that the bar shaped piezoelectric ceramic is trapezoidal.

4. fiber grating centre wavelength wide region tuner is characterized in that comprising:

Base plate (6) is arranged on the fixed leg (7) on the base plate;

Triangular supports (1), comprise left arm (1-1) and right arm (1-2) that top and fixed leg (7) are rotationally connected, leaving certain gaps uncovered by the economic plan between the base of left arm (1-1) and right arm (1-2), be used to place fiber grating (4), the double-end optical fiber of fiber grating (4) (3) passes from the two ends of left arm (1-1) and right arm (1-2) respectively;

Piezoelectric ceramic (5) is enclosed within on the pillar (8) that is fixed on base plate (6), is positioned between left arm (1-1) and the right arm (1-2), and tangent with left arm (1-1) and right arm (1-2).

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