CN1159614C - Metallized optical fibre distributed microheater for temp tuning of optical fibre device - Google Patents

Abstract

The present invention relates to a metallized optical fiber distributing microheater for the temperature tuning of an optical fiber device, which is mainly suitable for tuning an optical fiber grating and modulating the refractivity of an optical fiber. The present invention comprises a metal heating layer coated on the outer surfaces of a bare optical fiber or the optical fiber grating, wherein N electrodes which are more than two are uniformly distributed on the metal heating layer; the metal heating layer is divided into N heating units which are more than one and are connected in series. A temperature measuring element is placed on each heating units. The electrodes and the temperature measuring elements are all connected with a control circuit. The control circuit has two kinds of structures for selection. The temperature change of the metal heating layer is controlled by a computer through the control circuit; consequently, a tuning or a modulating purpose is realized. The present invention has the advantages of high heating efficiency and quick heating speed. The present invention can satisfy different requirements of temperature distribution along an optical fiber axis. The present invention has important application significance for dynamic dispersion compensation devices, high-order dispersion compensation devices, peculiar spectrum filters, etc.

Description

The metallization optical fiber distributed type micro-heater that is used for optical fibre device thermal tuning

Technical field:

The present invention relates to optical fibre device, particularly a kind of metallization optical fiber distributed type micro-heater that is used for optical fibre device thermal tuning.

Background technology:

In the tuning and optical fiber sensing technology of optical fiber, various optical fibre devices have been brought into play vital role as fiber grating, fibre optic interferometer etc.The wavelength tuning characteristic of these devices is performances of very paying close attention in the practical application.Fiber grating is a kind of narrowband reflection mode filter, and application request can tuning its peak.Especially in the dense wave division multipurpose communication system, need tunable light source, tunable wave filter.In chirp fibre-optical grating compensator with dispersion spare and long-period optical fibre raster gain flat filter, need dynamically to adjust its centre wavelength and chromatic dispersion compensation quantity, dynamically adjust the gain spectral curve.In these are used, also require to have higher tuned speed.At many fibre optic interferometers that are used for sensing and measurement, as optical fiber mach-Zehnder interferometer, need adjust, to obtain stable, sensitive output to the refractive index of an arm of interferometer; Also need an arm of interferometer is carried out index modulation, to obtain modulation output or switching characteristic.

Utilize optical fibre refractivity can realize tuning with temperature, stress and other physical influences.List of references [1] [Ball G.A., Morey W.W.Continuously tunable single-mode erbium fiber laser, Opt.Lett., 1992,17 (6): 420-422] report adopts piezoelectric ceramics (PZT) to make optical-fiber deformation, thereby reaches tuning purpose.According to the document, during optical-fiber deformation 90 μ m, wavelength tuning range is 0.72nm.The shortcoming of this structure is to apply very high voltage on PZT.

List of references [2] [Yu Youlong, Liu Zhiguo, Dong Xiaoyi, Wang Jiang, " the fiber grating linearity based on semi-girder is tuning ", optics journal, Vol.19, No.5, May, 1999] has proposed the semi-girder tunable technology.This structure is fixed on fiber grating on the side of semi-girder.During the motion of semi-girder free end, cause that a side stretches, the another side compression, thus make fiber grating generation deformation, reach tuning purpose.The tuned speed of this structure is slow.

List of references [3] [Xu M.G., Geiger H., Archambault J.L.et al., Novelinterrogating system for fiber Bragg grating sensors using an acousto-optic tunablefilter, Electron.Lett., 1993,29 (17): 1510-1511] utilize the refractive index of optical fiber and the relation of temperature, can carry out tuning to fiber grating by the temperature of control external environment.The heated optical fiber of heating arrangements distance that it adopts is distant, and therefore tuning efficient is low, and speed is slow.List of references [4] [Dong Xinyong, Wen Wuqi, Wei Yuhua, Liu Zhiguo, open Gui Yun and Dong Xiaoyi, " the metal tube encapsulation and the electric tuning of Fiber Bragg Grating ", photon journal, Vol.30, No.4, pp.422-424,2001] adopt and be a bit larger tham the metal sleeve of fibre diameter as calandria, by applying electric current fiber optic temperature is risen, reach tuning purpose.This structure has been improved the efficiency of heating surface.But because metal sleeve can not contact optical fiber fully, the thermal efficiency and tuned speed still are restricted.

List of references [5] [Eggleton B.J., et.al.Electrically Tunable Power EfficientDispersion Compensating Fiber Bragg Grating, IEEE Photonics TechnologyLetters, Vol.11, No.7, pp854-856,1999] adopt in the optical fiber surface direct metallized, pass through the tuning of current flow heats, made Dispersion Compensation Fiber Gratings.But practical application also needs the different parts of optical fiber or optical fibre device (as fiber grating) is carried out different require tuning, changes its transmission or spectrum of reflected light characteristic to reach.Therefore, a kind of element with distributed tuber function is necessary.Above-mentioned technology does not formerly have such function.

Summary of the invention:

The objective of the invention is in order to overcome the deficiency of above-mentioned technology formerly, the distribution heating element of a kind of direct preparation at the optical fiber outside surface be provided, with realize efficiently, at a high speed, on time and space, can regulate the tuner of control.

Micro-heater of the present invention comprises circuit board 7, is fixed in to have on the circuit board 7 and peels off the optical fiber bare fibre 3 of coat 4 outward.On the outside surface of bare fibre 3, be coated with METAL HEATING PROCESS layer 2; There is N 〉=2 electrode 5 to be added in equably on the METAL HEATING PROCESS layer 2, METAL HEATING PROCESS layer 2 is divided into the heating unit 201 of N 〉=1 series connection; Be equipped with temperature element 1 on each heating unit 201; Every electrode 5 and each temperature element 1 all are connected on the control circuit 6 on the circuit board 7.As shown in Figure 1.

Said control circuit 6 has two kinds of structures.First kind of structure is the potential coil 603 that is in series with on-off circuit 601, controllable silicon 602 and output buck transformer 604 between per two electrodes 5.Each on-off circuit 601, each controllable silicon 602 and each temperature element 1 all are connected to and trigger on the controller 605.Triggering controller 605 links to each other with computer interface 13 or digital signal processor.The temperature that is to say each heating unit 201 is controlled by triggering controller 605 by computing machine or digital signal processor.As shown in Figure 7.

Perhaps said control circuit 6 is second kind of structure, structure as shown in figure 10.Between per two electrodes 5, be parallel with variable resistor 606 with heating unit 201.Be connected on the stabilized voltage supply 607 after all variable resistor 606 series connection.Control end of all variable resistors 606 (or claiming the change resistance of resistance regulator to hold) and temperature element 1 all are connected on the equivalent resistance modulator 608.Equivalent resistance modulator 608 links to each other with computer interface 13 or digital signal processor.The temperature that is each heating unit 201 is equally controlled by equivalent resistance modulator 608 by computing machine and digital signal processor.

As required, can be surrounded by heat-insulation layer 8, keep the temperature of METAL HEATING PROCESS layer 2 in the periphery of METAL HEATING PROCESS layer 2.As shown in Figure 2.Perhaps being added with refrigerator 12 in the periphery of METAL HEATING PROCESS layer 2, is that the temperature of METAL HEATING PROCESS layer 2 is reduced rapidly.As shown in Figure 7.Perhaps neither add heat-insulation layer 8, also do not add refrigeration layer 12, as Fig. 1, Fig. 8, Fig. 9, shown in Figure 10.

Aforesaid structure, the METAL HEATING PROCESS layer 2 of micro-heater of the present invention are a kind of metal levels that adopts vacuum evaporation, electroless plating and electro-plating method directly to form on bare fibre 3 surfaces behind the coat 4 outside removing optical fiber.As above-mentioned, as required, can apply heat-insulation layer 8 outside the METAL HEATING PROCESS layer 2.The insulation coating material that is adopted in the embodiment of the invention is the exotic material that adopts the sol-gel technique preparation.Outside zone of heating 2, also can be equipped with refrigeration layer 12, promptly can contact with heat radiation or material of cooling.The cold junction that can adopt semiconductor cooler is as refrigeration layer 12.METAL HEATING PROCESS layer 2 adopts solder lead welding or high-temperature resistant conducting glue etc. with the connection between the electrode 5.

The general structure of micro-heater of the present invention as shown in Figure 1.METAL HEATING PROCESS layer 2 is in series by multistage heating unit 201.A temperature element 1 is installed on each section heating unit 201.This temperature element 1 adopts thermistor or thermocouple.The electrode 5 of micro-heater and temperature element 1 are connected on the control circuit 6 of driving circuit and Temperature Feedback.Optical fiber and control circuit all are produced on the printed circuit board (PCB) 7.Can obtain controlled tuning of Temperature Distribution by computing machine or digital signal processor (DSP).

Compare with the thermal tuning of technology formerly, micro-heater of the present invention has tangible advantage:

(1) thermal efficiency height.Because METAL HEATING PROCESS layer 2 is contact bare fibre 3 closely, heat directly imports fibre core into, and the efficient of heating is very high.If the specific heat of bare fibre 3 is C ₁The resistivity of METAL HEATING PROCESS layer 2 material is ρ, and specific heat is C ₂The thickness of METAL HEATING PROCESS layer 2 is h, and internal diameter is r (r equates with the external diameter of bare fibre 3, is generally 125 microns); The equivalent coefficient of heat transfer of METAL HEATING PROCESS layer 2 outside surface is s, can obtain, and when applying electric current I, temperature rise is:

$\mathrm{\&Delta;T}=\frac{{\mathrm{\&rho;<figure-callout\; id="2"\; label="I"\; filenames="C0213622200091.png,C0213622200092.png"\; state="\{\{state\}\}">I</figure-callout>}}^2}{{\mathrm{\&pi;}}^{2}h(2r+h)[r^2{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="C0213622200091.png,C0213622200101.png"\; state="\{\{state\}\}">C</figure-callout>}}_1+h(2r+h){\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="C0213622200091.png,C0213622200092.png"\; state="\{\{state\}\}">C</figure-callout>}}_2+2(r+h)s]}---\left(1\right)$

$\&ap;\frac{{\mathrm{\&rho;<figure-callout\; id="2"\; label="I"\; filenames="C0213622200091.png,C0213622200092.png"\; state="\{\{state\}\}">I</figure-callout>}}^2}{{2\mathrm{\&pi;}}^2{\mathrm{hr}}^2[\mathrm{<figure-callout\; id="1"\; label="r\; C"\; filenames="C0213622200091.png,C0213622200101.png"\; state="\{\{state\}\}">r</figure-callout>}{C}_{}{}_1+{2\mathrm{<figure-callout\; id="2"\; label="hC"\; filenames="C0213622200091.png,C0213622200092.png"\; state="\{\{state\}\}">hC</figure-callout>}}_2+2s]}---\left(2\right)$

(2) formula be h＜＜approximate during r.Because bare fibre 3 is very thin, the coating of METAL HEATING PROCESS layer 2 can be done very thinly, and METAL HEATING PROCESS layer 2 is not with there being other heat insulation or conducting stratums between the bare fibre 3, so the thermal efficiency can be done very highly.

(2) firing rate is fast.Because the volume weight of bare fibre 3 and METAL HEATING PROCESS layer 2 is very little, total thermal capacity is very little, so variation of temperature speed is very fast.According to the conduction law of heat, the heat of conduction is proportional to thermograde: Q=-κ T.κ is the thermal conductivity of fiber optic materials in the formula.The present invention directly is produced on METAL HEATING PROCESS layer 2 on the optical fiber surface, leaves the distance of fibre core and has only 60 microns.Therefore can obtain big thermograde.Total little speed that also helps thermal tuning of thermal capacity.Approx, the time Changing Pattern of temperature rising and decline can be described with following formula:

Rise: $T=T_0+\frac{P}{\mathrm{\&sigma;C}}[1-\exp (-\mathrm{\&sigma;t})];$ Descend: T=T ₀P is added power in+Δ Texp (σ t) formula, and C is a thermal capacity, and σ is for characterizing the parameter that heat dissipates, and it can be expressed as:

σ＝2s(r+h)/[r ²C ₁+(2r+h)hC ₂]≈2s/(rC ₁+2hC ₂)。

As seen thermal capacity has directly determined the speed that heats up, and little thermal capacity has guaranteed fast programming rate.If the refrigeration layer of the periphery of METAL HEATING PROCESS layer 2 12 adopts conductor refrigeration, can realize fast cooling rate.

(3) adopt structure shown in Figure 1, METAL HEATING PROCESS layer 2 is that the heating unit 201 by N 〉=1 series connection constitutes.By computer control, between different two electrodes, apply different electric currents, the temperature variation of then different heating units 201 is just different.So computer control can have the Temperature Distribution of desired certain special shape in the axial acquisition of bare fibre 3.This function has the important use meaning in application such as dynamic dispersion compensation, high-order dispersion compensation, peculiar spectrum wave filter.

Description of drawings:

Fig. 1: be micro-heater structural representation of the present invention.

Fig. 2: for micro-heater of the present invention in embodiment 1, the structural representation of electrode 5 quantity N=2.

Fig. 3: the structural representation that is used for modulation optical fiber optical grating wave filter (embodiment 2) for the present invention.

Fig. 4: be the transmission spectral line of micro-heater of the present invention at embodiment 2 thermal tuning fiber gratings.

Fig. 5: the fiber grating peak wavelength is with the variation relation curve of micro-heater working current in embodiment 2.

Fig. 6: curve time response of temperature modulation.

Fig. 7: be the embodiment of the invention 3, control circuit 6 is first kind of structural representation.

Fig. 8: the synoptic diagram of in the thermal tuning of passive fiber ring cavity, using for micro-heater embodiment 4 of the present invention.

Fig. 9: be the synoptic diagram of the present invention's distributed micro-heater application in dynamic dispersion compensation in embodiment 5.

Figure 10: for the present invention in embodiment 6, control circuit 6 is the synoptic diagram of second kind of structure.

Embodiment:

Embodiment 1:

Structure as shown in Figure 2.The quantity N=2 of electrode 5.METAL HEATING PROCESS layer 2 is to adopt the method for vacuum coating directly to be plated on bare fibre 3 outside surfaces.Periphery at METAL HEATING PROCESS layer 2 is coated with the heat-insulation layer 8 that exotic material constitutes.Control circuit 6 is above-mentioned first kind of structure.

Embodiment 2:

See structure shown in Figure 3.Adopt vacuum evaporation technique, sell off on the surface of fiber grating 10 having write ultraviolet light, be coated with the titanium platinum film as transition bed 11; Electroplated nickel metal layer as METAL HEATING PROCESS layer 2 at titanium platinum film outside surface.The transition bed 11 of titanium platinum film mainly be for make nickel METAL HEATING PROCESS layer 2 combine with fiber grating 10 close and firm more.At two electrodes 5 of two end lead weldings of nickel coating, control circuit 6 adopts above-mentioned first kind of structure.Just can power up stream at 5 at two electrodes carries out tuning.Fig. 4 is fiber grating 10 transmission spectrum curves that change with heating current.Fig. 5 is the funtcional relationship that peak wavelength changes with working current.Can see that wavelength moves basically square being directly proportional with electric current.Can tuning 1nm under 0.15 ampere electric current.Fig. 6 is the time curve of temperature variation.Figure middle and lower part curve I is the current waveform that applies, and top II adopts a single-frequency laser to make light source, with the fiber grating of micro-heater modulation as wave filter, the photosignal waveform of measurement.Can see that the rise time is roughly about 30ms.

Embodiment 3:

Structure as shown in Figure 7.Control circuit 6 adopts first kind of above-mentioned structure.Control circuit 6 adopts the conventional SCR rectification circuit and the structure of thermistor sensing.Can realize the control of Temperature Distribution.602 is controllable silicon among the figure, and 601 is on-off circuits, or the pulse signal driver, the 603rd, and the potential coil of output buck transformer 604.605 is the triggering controller that temperature comparison circuit and thyristor gating circuit constitute, and has digital signal processor (DSP) or computer interface 13.604 is many groups output buck transformers of giving distributed zone of heating 2 power supplies.The 12nd, the semiconductor freezer cold head is regulated its temperature and can be changed tuned speed as the refrigeration layer.The quantity N=5 of electrode 5, METAL HEATING PROCESS layer 2 is made of 201 series connection of N=4 heating unit.

Embodiment 4:

The present invention is used for the tuning of fiber optic passive device.Structure as shown in Figure 8 is the example of an adjustable passive optic fiber ring-shaped cavity 15.When light signal was imported from optical fiber 3, through coupling mechanism 14, a part of luminous energy entered fiber optic loop 16.Its key property is that output light signal phase place has been subjected to periodic modulation.This one-period is exactly one of its important parameter: free spectrum width Delta λ=λ ²/ nL.L is the length of fiber optic loop 16 in the formula; N is the refractive index of optical fiber 3, and it is the function of temperature.λ is the wavelength of input beam.Temperature need accurately be adjusted to certain numerical value in the application.Can on one section fiber optic loop 16, make METAL HEATING PROCESS layer 2 for this reason, thereby the free spectrum width is finely tuned.Control circuit 6 adopts above-mentioned second kind of structure.

Embodiment 5:

The present invention can be used for the dynamic dispersion compensation device of chirped fiber grating.Fig. 9 is its structural representation.On chirped fiber grating 18, prepared distributed METAL HEATING PROCESS layer 2 of the present invention.Electrode 5 quantity N=8, the temperature of METAL HEATING PROCESS layer 2 and distribution thereof are by control circuit 6 controls.Control circuit 6 adopts above-mentioned first kind of structure.Light signal is from input port 19 input of optical fiber circulator 17, and the waveform of light pulse is as shown in B goes into.Light pulse is through after the reflection of chirped fiber grating 18, from output port 20 outputs.Optical pulse waveform improves, and the pulsewidth compression is as B _ContractShown in.In order to obtain the optimum dispersion compensation effect, utilize the METAL HEATING PROCESS layer of making on the chirped fiber grating 18 2, can adjust the amplitude and the width of the reflectance spectrum of chirped fiber grating 18.B ₀And B ₁It is the curve synoptic diagram of dynamic tuning reflectance spectrum.

Embodiment 6:

Structure as shown in figure 10.Control circuit 6 adopts second kind of above-mentioned structure.Electrode 5 quantity N=5 on the METAL HEATING PROCESS layer 2.Variable resistor 606 all in parallel on the every section heating unit 201 on the distributed METAL HEATING PROCESS layer 2.Their resistance is by 608 controls of equivalent resistance adjuster.Change the resistance of variable resistor 606, can change the electric current that flows through METAL HEATING PROCESS layer 2.This control circuit 6 also is with digital signal processor or computer interface 13.All circuit is by stabilized current supply 607 power supplies.

Claims (4)

1, a kind of metallization optical fiber distributed type micro-heater that is used for optical fibre device thermal tuning comprises:

＜1〉circuit board (7) is fixed in the bare fibre (3) of peelling off the outer coat (4) of optical fiber on the circuit board (7), is coated with METAL HEATING PROCESS layer (2) on the outside surface of bare fibre (3);

It is characterized in that:

＜2〉there are N 〉=2 electrode (5) to be added in equably on the METAL HEATING PROCESS layer (2), METAL HEATING PROCESS layer (2) are divided into the heating unit (201) of N 〉=1 series connection;

＜3〉be equipped with temperature element (1) on each heating unit (201);

＜4〉every electrode (5) and each temperature element (1) all are connected on the control circuit (6) on the circuit board (7).

2. the metallization optical fiber distributed type micro-heater that is used for optical fibre device thermal tuning according to claim 1, it is characterized in that said control circuit (6) is the potential coil (603) that is in series with on-off circuit (601), controllable silicon (602) and output buck transformer (604) between per two electrodes (5), each on-off circuit (601), each controllable silicon (602) and each temperature element (1) all are connected to and trigger on the controller (605), trigger controller (605) and link to each other with computer interface (13) or digital signal processor.

3. the metallization optical fiber distributed type micro-heater that is used for optical fibre device thermal tuning according to claim 1, it is characterized in that said control circuit (6) is to be parallel with variable resistor (606) with heating unit (201) between per two electrodes (5), be connected on the stabilized voltage supply (607) after all variable resistors (606) series connection, control end of all variable resistors (606) and temperature element (1) all are connected on the equivalent resistance adjuster (608), and equivalent resistance adjuster (608) links to each other with computer interface (13) or digital signal processor.

4. the metallization optical fiber distributed type micro-heater that is used for optical fibre device thermal tuning according to claim 1, it is characterized in that at the peripheral of METAL HEATING PROCESS layer (2) or be surrounded by heat-insulation layer (8), perhaps be equipped with cooling layer (12), perhaps heat-insulation layer (8) and cooling layer (12) all do not have.

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