CN103018821A - Polarization maintaining optical fiber with small bending radius and manufacture method of polarization maintaining optical fiber - Google Patents

Abstract

The invention discloses a polarization maintaining optical fiber with a small bending radius and a manufacture method of the polarization maintaining optical fiber and relates to the field of optical fiber manufacture. The polarization maintaining optical fiber comprises a silica cladding, a core layer, a second silica cladding ring, a third fluorine-doped silica cladding ring and two stress cat eyes are sequentially arranged in the silica cladding from inside to outside, and the two stress cat eyes are in central symmetry with the core layer. By means of the manufacture method, the bending radius of the manufactured polarization maintaining optical fiber is smaller than 5mm, operating wavelength of the polarization maintaining optical fiber is 1550nm, and supplementary deterioration of the polarization maintaining optical fiber is under 0.4dB/km. According to the polarization maintaining optical fiber, under the condition that the bending radius is small, low-loss information transmission of the polarization maintaining optical fiber is achieved, low supplementary deterioration and good crosstalk characteristics of the polarization maintaining optical fiber are guaranteed, fiber optic sensors with small sizes can be manufactured by means of the polarization maintaining optical fiber, and requirements of users are satisfied.

Description

A kind of small-bend radius polarization maintaining optical fibre and manufacture method thereof

Technical field

The present invention relates to the fiber manufacturing field, relate in particular to a kind of small-bend radius polarization maintaining optical fibre and manufacture method thereof.

Background technology

PMF(Polarization Maintaining Optical Fiber, polarization-maintaining fiber) be called for short polarization maintaining optical fibre, along with the deep development of optical communication field, polarization maintaining optical fibre is widely applied with its good birefringence effect and linear polarization hold facility.

At present, comparatively common polarization maintaining optical fibre comprises covering, the stress appendix that its inside is provided with fibre core and is oppositely arranged along the fiber core radius direction.The refractive index contrast of fibre core and covering is 0.3%～0.5%, is spaced apart 6 μ m～17 μ m between the stress appendix that is oppositely arranged, and the diameter of each stress appendix is 21 μ m～32 μ m.This polarization maintaining optical fibre not only has good polarization retention performance, and has lower junction loss.

Along with fiber optic sensing device (for example optical fibre gyro) develops to miniaturization gradually, fiber optic sensing device is had higher requirement to the bending radius of polarization maintaining optical fibre.But above-mentioned polarization maintaining optical fibre is in the situation that guarantees additional attenuation, and its minimum bending radius is greater than 7.5mm.When the bending radius of polarization maintaining optical fibre when 7.5mm is following, the additional attenuation of polarization maintaining optical fibre not only can reach 1dB/km(decibel/km) more than, additional attenuation is higher, and the cross-talk of polarization maintaining optical fibre is greater than-20dB/km, cross talk characteristic is lower, and the changing value of polarization maintaining optical fibre cross-talk is greater than 5dB.

Because above-mentioned polarization maintaining optical fibre is difficult to guarantee its performance when bending radius is less, therefore above-mentioned polarization maintaining optical fibre is difficult to produce the less fiber optic sensing device of size, and fiber optic sensing device is difficult to can't satisfy people's demand to the miniaturization development.

Summary of the invention

For the defective that exists in the prior art, the object of the present invention is to provide a kind of small-bend radius polarization maintaining optical fibre and manufacture method thereof.Can be in the less situation of bending radius by the polarization maintaining optical fibre that method of the present invention produces, realize the low-loss communication of polarization maintaining optical fibre, polarization maintaining optical fibre not only can guarantee that its additional attenuation is lower, and cross talk characteristic is better, can produce the less fiber optic sensing device of size, satisfy people's demand.

For reaching above purpose, small-bend radius polarization maintaining optical fibre provided by the invention: comprise the 3rd quartzy covering ring of mixing fluorine, also comprise quartzy covering, mix the stress opal of sandwich layer, the second quartzy covering ring and two boron-dopings of germanium; Be provided with successively from the inside to the outside sandwich layer, the second quartzy covering ring, the 3rd quartzy covering ring and stress opal in the described quartzy covering, described stress opal arranges along the sandwich layer Central Symmetry, and the bending radius of described polarization maintaining optical fibre is less than 5mm; The operation wavelength of described polarization maintaining optical fibre is 1310nm, and its additional attenuation is below 0.6dB/km; The operation wavelength of described polarization maintaining optical fibre is 1550nm, and its additional attenuation is below 0.4dB/km.

On the basis of technique scheme, the refractive index of the described second quartzy covering ring and quartzy covering is identical.

On the basis of technique scheme, the radius ratio of the described second quartzy covering ring and sandwich layer is 1.5～1.0, the radius ratio of the described the 3rd quartzy covering ring and sandwich layer is 1.5～3.0, half of bee-line and the ratio of sandwich layer radius are 2.0～4.0 between two stress opals, and the radius ratio of described stress opal and sandwich layer is 2.0～8.0.

On the basis of technique scheme, the refractive index contrast of described sandwich layer and quartzy covering is 0.32%～1.5%, the refractive index contrast of the described the 3rd quartzy covering ring and quartzy covering is-1.5%～-0.3%, and the refractive index contrast of described stress opal and quartzy covering is-1.0%～-0.3%.

On the basis of technique scheme, the radius of described quartzy covering is 20um, 40um or 62.5um.

The manufacture method of polarization maintaining optical fibre provided by the invention may further comprise the steps:

A, put sleeve pipe in the plug outside, form solid bar, described sleeve pipe forms quartzy covering; Described plug comprises sandwich layer, the second quartzy covering ring and the 3rd quartzy covering ring; B, axially offer two stress through holes on solid bar, described stress through hole arranges along the sandwich layer Central Symmetry; Respectively the stress rods of two boron-dopings is combined with a stress through hole and forms the stress opal; C, under 2000 ℃～2300 ℃ temperature, will be drawn into bare fibre after the described solid bar melting, draw rate is 50m/min～350m/min, draw tension is 50g～180g; Air pressure in the pulling process in the described stress opal of control is identical, and keeping the interior air pressure of stress opal and the pressure difference of ambient pressure is 0.0001Mpa～0.01Mpa;

D, under 1200 ℃～1800 ℃ temperature, with the bare fibre stress relieving by annealing, coating and outer layer coating in the bare fibre outside applies from the inside to the outside successively, formation polarization maintaining optical fibre; The bending radius of described polarization maintaining optical fibre is less than 5mm, and the operation wavelength of described polarization maintaining optical fibre is 1310nm, and its additional attenuation is below 0.6dB/km; The operation wavelength of described polarization maintaining optical fibre is 1550nm, and its additional attenuation is below 0.4dB/km.

On the basis of technique scheme, the using plasma of plug described in steps A chemical vapour deposition technique is made in conjunction with the sleeve pipe method.

On the basis of technique scheme, the boron-doping in silicon dioxide of the using plasma of stress rods described in step B method is made.

On the basis of technique scheme, the air pressure identical process of control described in the step C in the described stress opal comprises: with two stress through holes tail pipe that continues respectively, every tail pipe is respectively by a voltage indicating device control air pressure, and all voltage indicating device controls are all coordinated control by a pressure controller.

On the basis of technique scheme, the Young modulus of interior coating is 0.1Mpa～50Mpa described in the step D, and the Young modulus of described outer layer coating is 0.3Gpa～1.0Gpa.

Beneficial effect of the present invention is:

(1) polarization maintaining optical fibre of the present invention is provided with the 3rd quartzy covering ring of mixing fluorine between sandwich layer and stress opal, the 3rd quartzy covering ring not only can effectively promote the counter-bending ability of polarization maintaining optical fibre, and other stress that reduced outside the de-stress opal that polarization maintaining optical fibre is subject to disturb, alleviated because of extraneous factor change bring the disturbance of polarization maintaining optical fibre cross-talk, effectively promoted the cross-talk stability of polarization maintaining optical fibre.

(2) polarization maintaining optical fibre of the present invention is in manufacture process, and two stress opals are connected with two voltage indicating devices respectively, and two voltage indicating devices are all by a pressure controller control.Be drawn in the process of bare fibre at solid bar, each voltage indicating device is independently controlled the air pressure in the stress opal, in case two air pressure differences that the stress opal is interior can be adjusted two voltage indicating devices by pressure controller.Therefore polarization maintaining optical fibre can guarantee constantly that during fabrication the air pressure in two stress opals is identical, not only can realize the in the same size of two stress opals, and the size of two stress opals is all remained in the rational scope.In sum, polarization maintaining optical fibre of the present invention not only cross talk characteristic is better, and the stability of the cross-talk of polarization maintaining optical fibre when crooked and temperature variation better.

(3) polarization maintaining optical fibre of the present invention is in manufacture process, and under 1200 ℃～1800 ℃ temperature, with other interference stress outside the opal that eliminates stress after the bare fibre annealing, most stress that the sandwich layer of polarization maintaining optical fibre is subject to come from the stress opal; And the passivation that can become after the annealing of stress opal, it is stable that the stress opal not only can keep when end surface grinding, can not burst.

(4) the bend-insensitive characteristic of polarization maintaining optical fibre of the present invention and cross-talk stability characteristic (quality) are better, and the bending radius of polarization maintaining optical fibre minimum is below 5mm.When the operation wavelength of polarization maintaining optical fibre was 1310nm, its added losses were below 0.6dB, and the cross-talk the when cross-talk when its bending radius is 5mm is 60mm with bending radius is compared, and the cross-talk when bending radius is 5mm changes below 3dB/km; When the operation wavelength of polarization maintaining optical fibre was 1550nm, its added losses were below 0.4dB, and the cross-talk the when cross-talk when its bending radius is 5mm is 60mm with bending radius is compared, and the cross-talk when bending radius is 5mm changes below 3dB/km.

Description of drawings

Fig. 1 is the structural representation of polarization maintaining optical fibre of the present invention;

Fig. 2 is the waveguiding structure synoptic diagram of polarization maintaining optical fibre of the present invention;

Fig. 3 is the structural representation that polarization maintaining optical fibre of the present invention draws moulding;

Fig. 4 is the synoptic diagram of the operation wavelength of polarization maintaining optical fibre of the present invention when being 1310nm;

Fig. 5 is the synoptic diagram of the operation wavelength of polarization maintaining optical fibre of the present invention when being 1550nm.

Among the figure: the quartzy covering of 1-, 2-sandwich layer, 3-the second quartzy covering ring, 4-stress opal, 5-the 3rd quartzy covering ring, 6-solid bar, 7-stress rods, 8-tail pipe, 9-bores end, 10-voltage indicating device, 11-pressure controller, 12-bare fibre, the 13-attemperator, 14-tester, 15-coating unit, 16-solidification equipment, the 17-deflecting roller, the 18-tensiometer, the 19-traction wheel, 20-leads tow wheel, the 21-locating wheel, 22-receives wire tray tool, 23-heating arrangement.

Embodiment

Below in conjunction with drawings and Examples the present invention is described in further detail.

The computing method of refractive index contrast at first are described.

Refractive index contrast adopts formula to be: the * 100% of Δ=(n1-n2)/(n1+n2)

Δ represents refractive index contrast in the above-mentioned formula, and n2 represents the refractive index of quartzy covering 1; When the refractive index contrast between calculatingsandwich layer 2 and the quartzy covering 1, the n1 in the above-mentioned formula represents the refractive index ofsandwich layer 2; When the refractive index contrast between calculating the 3rd quartzy coveringring 5 and the quartzy covering 1, the n1 in the above-mentioned formula represents the refractive index of the 3rd quartzy coveringring 5; When the refractive index contrast between calculatedstress opal 4 and the quartzy covering 1, the n1 in the above-mentioned formula represents the refractive index ofstress opal 4.

Referring to shown in Figure 1, the polarization maintaining optical fibre in the embodiment of the invention comprises quartzy covering 1, and quartzy covering 1 inside is provided withsandwich layer 2, the secondquartzy covering ring 3 of mixing germanium, the 3rd quartzy coveringring 5 of mixing fluorine and thestress opal 4 of boron-doping from the inside to the outside successively;Stress opal 4 is two, and twostress opals 4 are alongsandwich layer 2 Central Symmetry settings.The bending radius of polarization maintaining optical fibre is less than 5mm; The operation wavelength of polarization maintaining optical fibre is 1310nm, and its additional attenuation is below 0.6dB/km; The operation wavelength of polarization maintaining optical fibre is 1550nm, and its additional attenuation is below 0.4dB/km.

Referring to Fig. 1, shown in Figure 2, the radius ofsandwich layer 2 is that r1, its refractive index are n1; The radius of the secondquartzy covering ring 3 is that r2, its refractive index are n2; The radius of the 3rd quartzy coveringring 5 is that r3, its refractive index are n3; Half of bee-line is that r4, its refractive index are n4 between twostress opals 4; The radius ofstress opal 4 is that r5, its refractive index are n5; The radius of quartzy covering 1 is that r6, its refractive index are n6; Wherein the refractive index of n2, n4 and n6 is identical.

The radius of quartzy covering 1 is 20um, 40um or 62.5um; For the bend-insensitive characteristic that realizes the polarization maintaining optical fibre waveguide and good cross-talk with clap long performance, the secondquartzy covering ring 3 is 1.5～1.0 with the radius ratio ofsandwich layer 2, the 3rd quartzy coveringring 5 is 1.5～3.0 with the radius ratio ofsandwich layer 2, half of bee-line and the ratio ofsandwich layer 2 radiuses are 2.0～4.0 between twostress opals 4, andstress opal 4 is 2.0～8.0 with the radius ratio of sandwich layer 2.In order to realize the good mode field diameter of polarization maintaining optical fibre, cutoff wavelength, cross-talk performance and clap the property such as long that the secondquartzy covering ring 3 is identical with the refractive index of quartzy covering 1; Refractive index contrast betweensandwich layer 2 and the quartzy covering 1 is 0.32%～1.5%, refractive index contrast between the 3rd quartzy coveringring 5 and the quartzy covering 1 is-1.5%～-0.3%, and the refractive index contrast betweenstress opal 4 and the quartzy covering 1 is-1.0%～-0.3%.

Referring to Fig. 1, shown in Figure 3, the manufacture method of polarization maintaining optical fibre in the embodiment of the invention may further comprise the steps:

S101: the using plasma chemical vapour deposition technique is made plug in conjunction with the sleeve pipe legal system, and plug comprisessandwich layer 2, the secondquartzy covering ring 3 and the 3rd quartzy coveringring 5, puts sleeve pipe in the plug outside, forms solid bar 6, and sleeve pipe forms quartzy covering 1.

S102: axially offer two stress through holes on solid bar 6, described stress through hole is alongsandwich layer 2 Central Symmetry settings, adopts diamond head when offering the stress through hole, and in conjunction with machinery location, infrared induction location and electronic-controlled.

S103: the stress rods 7 of two boron-dopings is made in the boron-doping in silicon dioxide of using plasma method, and the homogeneity of the stress rods 7 that the using plasma method is made is better.The surface of stress rods 7 is processed, make the external diameter of stress rods 7 less than aperture 0.1 mm of stress through hole～0.2mm, each stress rods 7 is combined with a stress through holeforms stress opal 4.

S104: with the top of each stress through hole on the solid bar 6 or the bottom tail pipe 8 that continues, tail pipe 8 is made by quartz; Solid bar 6 and tail pipe 8 meltings are integrated.

S105: solid bar 6 is not had an end of tail pipe 8 be drawn intocone end 9 at lathe, in order to draw polarization maintaining optical fibre.

S106: every tail pipe 8 is connected with avoltage indicating device 10, and allvoltage indicating devices 10 all are connected with a pressure controller 11, form polarization-preserving fiber preform.

S107: polarization-preserving fiber preform is placed on the wire-drawer-tower, draws after high-temperature fusion under 2000 ℃～2300 ℃ the temperature throughheating arrangement 23 and formbare fibre 12; In the pulling process, when the radius of quartzy covering 1 was 62.5um, draw rate was 50m/min～300m/min, and draw tension is 60g～180g; When the radius of quartzy covering 1 was 40um, draw rate was 50m/min～350m/min, and draw tension is 50g～150g; When the radius of quartzy covering 1 was 20um, draw rate was 50m/min, and draw tension is 50g.

In the pulling process, air pressure byvoltage indicating device 10 control tail pipes 8 and thestress opal 4 corresponding with tail pipe 8, keep the air pressure of twostress opals 4 and the pressure difference of ambient pressure to be 0.0001Mpa～0.01Mpa, so that the diameter of two stress opals 4 of good control.Air pressure difference in the pulling process as in two stress opals ofdiscovery 4 can be regulated by 11 pairs ofvoltage indicating devices 10 of pressure controller, and is identical to guarantee the air pressure in two stress opals 4.

S108: be 1200 ℃～1800℃ attemperator 13 withbare fibre 12 through excess temperature,bare fibre 12 is annealed inattemperator 13 and is eliminated stress, so that the stress that only hasstress opal 4 to produce in thebare fibre 12.

S109:bare fibre 12 is applied interior coating and outer layer coating tobare fibre 12 through 15, twocoating units 15 of two coating units afterinstrument 14 tests after tested successively from the inside to the outside successively; When applying interior coating and outer layer coating, the coating processes of employing is wet humidification coating processes or dried humidification coating processes, and the curing mode of employing is ultra-violet curing mode or heat curing mode.Be coated with thebare fibre 12 of interior coating and outer layer coating aftersolidification equipment 16 solidifies, form polarization maintaining optical fibre; The bending radius of polarization maintaining optical fibre is less than 5mm, and when the operation wavelength of polarization maintaining optical fibre was 1310nm, its additional attenuation was below 0.6dB/km; When the operation wavelength of polarization maintaining optical fibre was 1550nm, its additional attenuation was below 0.4dB/km.Polarization maintaining optical fibre is pressed preset sequence by locatingwheel 21 and is received silk on receiptswire tray tool 22 successively through deflecting roller 17,tensiometer 18, traction wheel 19 with after leadingtow wheel 20.

The Young modulus of interior coating is 0.1Mpa～50Mpa, and the Young modulus of interior coating is lower, can cushion the stress in the external world that polarization maintaining optical fibre is subject to.Outer coating material can be the coating material of normal temperature work according to different demands, also can be high temperature resistant work coating material; The Young modulus of outer layer coating is 0.3Gpa～1.0Gpa, and the Young modulus of outer layer coating is higher, can form rigid structure, and then bears the extraneous stress that produces, and reduces polarization maintaining optical fibre and is subject to extraneous interference.

Below by three specific embodiments the present invention is specifically described.

Embodiment 1: the radius of quartzy covering 1 is 40um.

The using plasma chemical vapour deposition technique is made plug in conjunction with the sleeve pipe legal system, and plug comprisessandwich layer 2, the secondquartzy covering ring 3 and the 3rd quartzy coveringring 5; Put sleeve pipe in the plug outside, form solid bar 6, sleeve pipe forms quartzy covering 1.Axially offer two stress through holes on solid bar 6, described stress through hole is alongsandwich layer 2 Central Symmetry settings, adopts diamond head when offering the stress through hole, and in conjunction with machinery location, infrared induction location and electronic-controlled.

The stress rods 7 of two boron-dopings is made in the boron-doping in silicon dioxide of using plasma method, and the homogeneity of the stress rods 7 that the using plasma method is made is better.The surface of stress rods 7 is processed, make the external diameter of stress rods 7 less than aperture 0.1 mm of stress through hole, each stress rods 7 is combined with a stress through hole forms stress opal 4.With the top (head end) of each stress through hole on the solid bar 6 tail pipe 8 that continues, tail pipe 8 is made by quartz; Solid bar 6 and tail pipe 8 meltings are integrated.Solid bar 6 bottoms (tail end) are drawn intocone end 9 at lathe, in order to draw polarization maintaining optical fibre.

Every tail pipe 8 is connected with avoltage indicating device 10, and allvoltage indicating devices 10 all are connected with a pressure controller 11, form polarization-preserving fiber preform.Polarization-preserving fiber preform is placed on the wire-drawer-tower, draws after high-temperature fusion under 2000 ℃～2300 ℃ the temperature throughheating arrangement 23 and formbare fibre 12, draw rate is 50m/min～350m/min, and draw tension is 50g～150g.In the pulling process, be-0.01Mpa by the air pressure involtage indicating device 10 control tail pipes 8 and thestress opal 4; As it is rear less than another stress through hole to find that a stress through hole shrinks, and when causingsandwich layer 2 distortion, regulates thevoltage indicating device 10 corresponding with less stress through hole by pressure controller 11, and the pressure of thesevoltage indicating device 10 outputs is turned down.

Air pressure difference in the pulling process as in two stress opals ofdiscovery 4 can be regulated by 11 pairs ofvoltage indicating devices 10 of pressure controller, and is identical to guarantee the air pressure in two stress opals 4.When drawing the tail end of polarization-preserving fiber preform, the air pressure in two tail pipes 8 need to reduce, and this moment, the controlled pressure controller 11, so that the minimum that two tail pipe 8 internal gas pressures reduce is-0.001Mpa.

Throughattemperator 13,attemperator 13 is 1800 ℃ near the temperature of top withbare fibre 12, and the temperature of close below is 1500 ℃, andbare fibre 12 is annealed inattemperator 13 and eliminated stress; Barefibre 12 is applied interior coating and outer layer coating from the inside to the outside, and the Young modulus of interior coating is 0.1Mpa～50Mpa, and the Young modulus of outer layer coating is 0.3Gpa～1.0Gpa.Be coated with thebare fibre 12 of interior coating and outer layer coating aftersolidification equipment 16 solidifies, form polarization maintaining optical fibre; Polarization maintaining optical fibre is pressed preset sequence by locatingwheel 21 and is received silk on receiptswire tray tool 22 successively through deflecting roller 17,tensiometer 18, traction wheel 19 with after leadingtow wheel 20.

Now adopt said method to make five polarization maintaining optical fibres, its parameter is shown in Table 1, and its additional attenuation and added losses are referring to Fig. 4, (along slope coordinate represents additional attenuation among Fig. 4 and Fig. 5, and lateral coordinates represents added losses) shown in Figure 5.Referring to table 1, Fig. 4 and Fig. 5 as can be known, for theoptical fiber 1 andoptical fiber 5 of 1310nm, the additional attenuation ofoptical fiber 1 andoptical fiber 5 is respectively 0.53dB/km and 0.43dB/km, all less than 0.6dB/km for operation wavelength.Be under the condition of 5mm in bending radius, the added losses ofoptical fiber 1 andoptical fiber 5 are respectively 0.71dB and 0.75dB, less than 0.8dB;Optical fiber 1 and the cross-talk ofoptical fiber 5 when bending radius is 5mm are that the absolute value variable quantity of 60mm is respectively 2.78dB/km and 2.75dB/km with respect to bending radius, all less than 3.0dB/km.Foroptical fiber 2,optical fiber 3 and theoptical fiber 4 of 1550nm, the additional attenuation ofoptical fiber 2,optical fiber 3 andoptical fiber 4 is respectively 0.35dB/km, 0.39dB/km and 0.38dB/km, all less than 0.4dB/km for operation wavelength.Be under the condition of 5mm in bending radius, the crooked added losses ofoptical fiber 2,optical fiber 3 andoptical fiber 4 are respectively 0.80dB, 0.85dB and 0.91dB;Optical fiber 2,optical fiber 3 and the cross-talk ofoptical fiber 4 when bending radius is 5mm are that the absolute value variable quantity of the cross-talk of 60mm is respectively 2.73dB/km, 2.75dB/km and 2.77dB/km with respect to bending radius.

The polarization maintaining optical fibre parameter list that quartzy covering 1 radius of table 1 is 40um

	Optical fiber 1	Optical fiber 2	Optical fiber 3	Optical fiber 4	Optical fiber 5
						r1?um	3.0	4.0	5.0	6.0	7.5
△n1	1.25%	1.00%	0.85%	0.50%	0.32%
						r2/r1	1.5	1.1	1.2	1.3	1.0
r3/r1	3.0	2.6	1.8	1.6	1.5
						△n3	-1.50%	-1.25%	-1.00%	-0.50%	-0.50%
r4/r1	4.0	3.0	2.5	2.2	2.0
						r5/r1	7.0	5.0	4.0	3.0	2.0
△n5	-1.00%	-0.90%	-0.75%	-0.50%	-0.40%
						Drawing speed m/min	50	100	150	220	350
Drawingtensile force g	50	60	90	120	150
						Interior coating Young modulus Mpa	50	20	0.5	0.3	0.1
Outer layer coating Young modulus Gpa	1.0	0.8	0.7	0.6	0.3

R1 is the sandwich layer radius in the table 1; △ n1 is the refractive index contrast ofsandwich layer 2 and quartzy covering 1; R2/r1 is the radius ratio of the secondquartzy covering ring 3 andsandwich layer 2; R3/r1 is the radius ratio of the 3rd quartzy coveringring 5 andsandwich layer 2; △ n3 is the refractive index contrast of the 3rd quartzy coveringring 5 and quartzy covering 1; R4/r1 is half of bee-line and the ratio ofsandwich layer 2 radiuses between twostress opals 4; R5/r1 is the radius ratio ofstress opal 4 andsandwich layer 2; △ n5 is the refractive index contrast ofstress opal 4 and quartzy covering 1.

Embodiment 2: the radius ofquartzy covering 1 is 62.5um.

The using plasma chemical vapour deposition technique is made plug in conjunction with the sleeve pipe legal system, and plug comprisessandwich layer 2, the secondquartzy covering ring 3 and the 3rdquartzy covering ring 5; Put sleeve pipe in the plug outside and form solid bar 6, sleeve pipe forms quartzy covering 1.Axially offer two stress through holes on solid bar 6, described stress through hole is alongsandwich layer 2 Central Symmetry settings, adopts diamond head when offering the stress through hole, and in conjunction with machinery location, infrared induction location and electronic-controlled.

The stress rods 7 of two boron-dopings is made in the boron-doping in silicon dioxide of using plasma method, and the homogeneity of the stress rods 7 that the using plasma method is made is better.The surface of stress rods 7 is processed, make the external diameter of stress rods 7 less than aperture 0.2 mm of stress through hole, each stress rods 7 is combined with a stress through hole forms stress opal 4.With the top (head end) of each stress through hole on the solid bar 6 tail pipe 8 that continues, tail pipe 8 is made by quartz; Solid bar 6 and tail pipe 8 meltings are integrated.Solid bar 6 bottoms (tail end) are drawn intocone end 9 at lathe, in order to draw polarization maintaining optical fibre.

Every tail pipe 8 is connected with avoltage indicating device 10, and allvoltage indicating devices 10 are connected with a pressure controller 11, form polarization-preserving fiber preform.Polarization-preserving fiber preform is placed on the wire-drawer-tower, is to draw after the high-temperature fusion under the condition of 5mm to formbare fibre 12 in bending radius throughheating arrangement 23, and draw rate is 50m/min～300m/min, and draw tension is 60g～180g.In the pulling process, by the air pressure involtage indicating device 10 control tail pipes 8 and thestress opal 4 be-0.005Mpa; As it is rear less than another stress through hole to find that a stress through hole shrinks, and when causingsandwich layer 2 distortion, regulates thevoltage indicating device 10 corresponding with less stress through hole by pressure controller 11, and the pressure of thesevoltage indicating device 10 outputs is turned down.

Air pressure difference in the pulling process as in two stress opals ofdiscovery 4 can be regulated by 11 pairs ofvoltage indicating devices 10 of pressure controller, and is identical to guarantee the air pressure in two stress opals 4.When drawing the tail end of polarization-preserving fiber preform, the air pressure in two tail pipes 8 need to reduce, and this moment, the controlled pressure controller 11, so that the minimum that two tail pipe 8 internal gas pressures reduce is-0.001Mpa.

Throughattemperator 13,attemperator 13 is 1700 ℃ near the temperature of top withbare fibre 12, and the temperature of close below is 1200 ℃, andbare fibre 12 is annealed inattemperator 13 and eliminated stress;Bare fibre 12 is applied interior coating and outer layer coating from the inside to the outside, and the Young modulus of interior coating is 0.1Mpa～50Mpa, and the Young modulus of outer layer coating is 0.3Gpa～1.0Gpa.Be coated with thebare fibre 12 of interior coating and outer layer coating aftersolidification equipment 16 solidifies, form polarization maintaining optical fibre; Polarization maintaining optical fibre is pressed preset sequence by locatingwheel 21 and is received silk on receiptswire tray tool 22 successively through deflecting roller 17,tensiometer 18, traction wheel 19 with after leadingtow wheel 20.

Now adopt said method to make five polarization maintaining optical fibres, its parameter is shown in Table 2, and its additional attenuation and added losses are referring to Fig. 4, (along slope coordinate represents additional attenuation among Fig. 4 and Fig. 5, and lateral coordinates represents added losses) shown in Figure 5.

Referring to table 2, Fig. 4 and Fig. 5 as can be known, for the optical fiber 6 and optical fiber 10 of 1310nm, the additional attenuation of optical fiber 6 and optical fiber 10 is respectively 0.45dB/km and 0.53dB/km, all less than 0.6dB/km for operation wavelength.Be under the condition of 5mm in bending radius, the added losses of optical fiber 6 and optical fiber 10 are respectively 0.76dB and 0.79dB, less than 0.8dB; Absolute value variable quantity when optical fiber 6 and the cross-talk of optical fiber 10 when bending radius is 5mm are 60mm with respect to bending radius is respectively 2.72dB/km and 2.77dB/km, all less than 3.0dB/km.For optical fiber 7, optical fiber 8 and the optical fiber 9 of 1550nm, the additional attenuation of optical fiber 7, optical fiber 8 and optical fiber 9 is respectively 0.31dB/km for operation wavelength, and 0.35dB/km and 0.36dB/km are all less than 0.4dB/km.Be under the condition of 5mm in bending radius, the crooked added losses of optical fiber 7, optical fiber 8 and optical fiber 9 are respectively 0.87dB, 0.92dB and 0.98dB; Optical fiber 7, optical fiber 8 and the cross-talk of optical fiber 9 when bending radius is 5mm are that the absolute value variable quantity of the cross-talk of 60mm is respectively 2.63dB/km with respect to bending radius, and 2.55dB/km and 2.87dB/km are all less than 3dB/km.

Quartzy covering 1 radius of table 2 is the parameter list of the polarization maintaining optical fibre of 62.5um

	Optical fiber 6	Optical fiber 7	Optical fiber 8	Optical fiber 9	Optical fiber 10
						r1（um）	3.5	5.0	6.0	7.0	8.0
△n1	1.50%	1.00%	0.85%	0.50%	0.32%
						r2/r1	1	1.1	1.2	1.3	1.5
r3/r1	1.5	2	2.1	2.4	3
						△n3	-1.25%	-1.00%	-0.80%	-0.50%	-0.30%
r4/r1	2.0	2.5	3.0	3.0	4.0
						r5/r1	8.0	6.0	5.0	3.0	2.5
△n5	-0.90%	-0.80%	-0.70%	-0.50%	-0.30%
						Drawing speed m/min	50	100	150	200	300
Drawingtensile force g	60	80	100	120	180
						Interior coating Young modulus Mpa	50.0	20.0	0.5	0.3	0.1
Outer layer coating Young modulus Gpa	1.0	0.8	0.7	0.6	0.3

R1 is the sandwich layer radius in the table 2; △ n1 is the refractive index contrast ofsandwich layer 2 andquartzy covering 1; R2/r1 is the radius ratio of the secondquartzy covering ring 3 andsandwich layer 2; R3/r1 is the radius ratio of the 3rdquartzy covering ring 5 andsandwich layer 2; △ n3 is the refractive index contrast of the 3rdquartzy covering ring 5 andquartzy covering 1; R4/r1 is half of bee-line and the ratio ofsandwich layer 2 radiuses between twostress opals 4; R5/r1 is the radius ratio ofstress opal 4 andsandwich layer 2; △ n5 is the refractive index contrast ofstress opal 4 andquartzy covering 1.

Embodiment 3: the radius ofquartzy covering 1 is 20um.

The present invention has also carried out the development of cladding radius 1 for the minimum polarization maintaining optical fibre of 20um.The radius of sandwich layer 2 is 3.0um, and sandwich layer 2 is 0.6% with the refractive index contrast of quartzy covering 1.The radius of the second quartzy covering ring 3 is 3.3um, and the second quartzy covering ring 3 is 1.1 with the radius ratio of sandwich layer 2.The radius of the 3rd quartzy covering ring 5 is 4.5um, and the radius ratio of the 3rd quartzy covering ring 5 and sandwich layer 2 is that the refractive index contrast of 1.5, the three quartzy covering rings 5 and quartzy covering 1 is-0.5%.Half of bee-line is 6.0um between two stress opals 4, and half of bee-line and the ratio of sandwich layer 2 radiuses are 2.0 between two stress opals 4.The radius of stress opal 4 is 6.0un, and stress opal 4 is 2.0 with the radius ratio of sandwich layer 2, and stress opal 4 and refractive index contrast quartzy covering 1 are-0.8%.When making this polarization maintaining optical fibre, attemperator 13 is 1500 ℃ near the temperature of top, and the temperature of close below is 1200 ℃; Interior coating adopts the 0.1Mpa Young modulus coating of ultra-soft, and outer layer coating adopts the coating of the Young modulus of extremely hard 1.0Gpa.

Draw rate when making this polarization maintaining optical fibre is 50m/min, and draw tension is 50g; In the pulling process, by the air pressure involtage indicating device 10 control tail pipes 8 and thestress opal 4 be-0.0001Mpa.As it is rear less than another stress through hole to find that a stress through hole shrinks, and when causingsandwich layer 2 distortion, regulates thevoltage indicating device 10 corresponding with less stress through hole by pressure controller 11, and the pressure of thesevoltage indicating device 10 outputs is turned down.

The operation wavelength of this polarization maintaining optical fibre is 1310nm, and the additional attenuation of this polarization maintaining optical fibre is 0.58dB/km; This polarization maintaining optical fibre is under the condition of 3mm in bending radius, and added losses are 0.72dB, and bending radius is that the cross-talk of 3mm and the absolute value of the cross-talk variable quantity that bending radius is 60mm are 2.85dB/km.

The present invention is not limited to above-mentioned embodiment, for those skilled in the art, under the prerequisite that does not break away from the principle of the invention, can also make some improvements and modifications, and these improvements and modifications also are considered as within protection scope of the present invention.The content that is not described in detail in this instructions belongs to the known prior art of this area professional and technical personnel.

Claims (10)

1. a small-bend radius polarization maintaining optical fibre is characterized in that: comprise the 3rd quartzy covering ring (5) of mixing fluorine, also comprise quartzy covering (1), mix the stress opal (4) of sandwich layer (2), the second quartzy covering ring (3) and two boron-dopings of germanium; Be provided with successively from the inside to the outside sandwich layer (2), the second quartzy covering ring (3), the 3rd quartzy covering ring (5) and stress opal (4) in the described quartzy covering (1), described stress opal (4) is along sandwich layer (2) Central Symmetry setting, and the bending radius of described polarization maintaining optical fibre is less than 5mm; The operation wavelength of described polarization maintaining optical fibre is 1310nm, and its additional attenuation is below 0.6dB/km; The operation wavelength of described polarization maintaining optical fibre is 1550nm, and its additional attenuation is below 0.4dB/km.

2. polarization maintaining optical fibre as claimed in claim 1, it is characterized in that: the described second quartzy covering ring (3) is identical with the refractive index of quartzy covering (1).

3. polarization maintaining optical fibre as claimed in claim 1, it is characterized in that: the described second quartzy covering ring (3) is 1.5～1.0 with the radius ratio of sandwich layer (2), the described the 3rd quartzy covering ring (5) is 1.5～3.0 with the radius ratio of sandwich layer (2), half of bee-line and the ratio of sandwich layer (2) radius are 2.0～4.0 between two stress opals (4), and described stress opal (4) is 2.0～8.0 with the radius ratio of sandwich layer (2).

4. polarization maintaining optical fibre as claimed in claim 1, it is characterized in that: described sandwich layer (2) is 0.32%～1.5% with the refractive index contrast of quartzy covering (1), the described the 3rd quartzy covering ring (5) is-1.5%～-0.3% with the refractive index contrast of quartzy covering (1), and described stress opal (4) is-1.0%～-0.3% with the refractive index contrast of quartzy covering (1).

5. polarization maintaining optical fibre as claimed in claim 1, it is characterized in that: the radius of described quartzy covering (1) is 20um, 40um or 62.5um.

6. the manufacture method based on the arbitrary described polarization maintaining optical fibre of claim 1 to 5 is characterized in that, may further comprise the steps:

A, put sleeve pipe in the plug outside, form solid bar, described sleeve pipe forms quartzy covering (1); Described plug comprises sandwich layer (2), the second quartzy covering ring (3) and the 3rd quartzy covering ring (5);

B, axially offer two stress through holes on solid bar, described stress through hole is along sandwich layer (2) Central Symmetry setting; Respectively the stress rods of two boron-dopings is combined with a stress through hole and forms stress opal (4);

C, under 2000 ℃～2300 ℃ temperature, will be drawn into bare fibre after the described solid bar melting, draw rate is 50m/min～350m/min, draw tension is 50g～180g; Air pressure in the pulling process in the described stress opal of control (4) is identical, and keeping the interior air pressure of stress opal (4) and the pressure difference of ambient pressure is 0.0001Mpa～0.01Mpa;

D, under 1200 ℃～1800 ℃ temperature, with the bare fibre stress relieving by annealing, coating and outer layer coating in the bare fibre outside applies from the inside to the outside successively, formation polarization maintaining optical fibre; The bending radius of described polarization maintaining optical fibre is less than 5mm, and the operation wavelength of described polarization maintaining optical fibre is 1310nm, and its additional attenuation is below 0.6dB/km; The operation wavelength of described polarization maintaining optical fibre is 1550nm, and its additional attenuation is below 0.4dB/km.

7. polarization maintaining optical fibre as claimed in claim 6, it is characterized in that: the using plasma of plug described in steps A chemical vapour deposition technique is made in conjunction with the sleeve pipe method.

8. polarization maintaining optical fibre as claimed in claim 6, it is characterized in that: the boron-doping in silicon dioxide of the using plasma of stress rods described in step B method is made.

9. polarization maintaining optical fibre as claimed in claim 6, it is characterized in that, the identical process of air pressure described in the step C in the control described stress opal (4) comprises: with two stress through holes tail pipe that continues respectively, every tail pipe is respectively by a voltage indicating device control air pressure, and all voltage indicating device controls are all coordinated control by a pressure controller.

10. polarization maintaining optical fibre as claimed in claim 6 is characterized in that: the Young modulus of coating is 0.1Mpa～50Mpa in described in the step D, and the Young modulus of described outer layer coating is 0.3Gpa～1.0Gpa.

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