CN212808694U

CN212808694U - Compact type online three-port optical fiber wavelength division multiplexer with high coaxiality

Info

Publication number: CN212808694U
Application number: CN202021656234.9U
Authority: CN
Inventors: 叶雪梅; 叶满
Original assignee: Shanghai China Sciences Co ltd; Shanghai Zhongke Chuangxin Communication Equipment Co ltd; SHANGHAI CHINA SCIENCE FIBEROPTIC COMPONENTS CO Ltd
Current assignee: Shanghai China Sciences Co ltd; Shanghai Zhongke Chuangxin Communication Equipment Co ltd; SHANGHAI CHINA SCIENCE FIBEROPTIC COMPONENTS CO Ltd
Priority date: 2020-08-11
Filing date: 2020-08-11
Publication date: 2021-03-26
Anticipated expiration: 2030-08-11

Abstract

The utility model relates to an online three port optical fiber wavelength division multiplexer that compact axiality is high, wherein, three port optical fiber wavelength division multiplexer include the single optic fibre of the two optical fiber pigtail of input, the radial gradual change of input self-focusing lens Glens, wavelength division multiplexing light filter, the radial gradual change self-focusing lens Glens of output and the two optical fiber pigtail of output, wherein the single optic fibre pigtail of the two optical fibers of output include the two optical fiber capillary of second and a second optic fibre, the second optic fibre be located two holes of the two optical fiber capillary of second in one of them hole, the second optic fibre conduct the optical fiber wavelength division multiplexer's transmission end. The three-port optical fiber wavelength division multiplexer adopting the structure has the advantages of small overall transverse offset, small overall axial angle deviation, high mode coupling efficiency, high coaxiality, strong linearity, high return loss, compact size and accurate packaging, and can be widely applied to the field of optical fiber communication.

Description

Compact type online three-port optical fiber wavelength division multiplexer with high coaxiality

Technical Field

The utility model relates to an optics field especially relates to optical transmission technical field, specifically indicates an online three port optical fiber wavelength division multiplexer that compact axiality is high.

Background

Currently, fiber wavelength division multiplexers, such as FTTH, MWDM, CWDM, DWDM, WITH, etc., generally use a structure configuration: one end of the single-hole single-fiber collimator is a single-fiber end-fiber and single-hole focusing lens packaged by a glass tube, the production process of the port is a process of adding a single-fiber end-fiber, the debugging method is generally a transmission collimation method, the focusing constant of an output end focusing lens a17 with the outer diameter of 1.8mm is generally 0.326@1550nm, the central refractive index is 1.590@1550nm, 0.23 circumference pitch, one surface is a plane, the other surface is polished by 8 degrees and plated with a corresponding anti-reflection film layer, and the end surface of the single-hole single-fiber end-fiber a15 is polished by 8 degrees and plated with a corresponding anti-reflection; the other end is a double-fiber collimator (composed of an input end double-fiber tail fiber a1 and an input end focusing lens a 16) and a wavelength division multiplexing filter, the process is that the wavelength division multiplexing filter is added with a radial gradient self-focusing lens component and a double-fiber tail fiber process, the double-fiber tail fiber part is packaged by a glass tube, the debugging method is generally a reflection collimation method, the radial gradient self-focusing lens with the outer diameter of 1.8mm is generally a focusing constant of 0.326@1550nm, the central refractive index of 1.590@1550nm and the circumferential pitch of 0.248, one surface is a plane, and the other surface is polished by 8 degrees and plated with a corresponding anti-reflection film layer. The spacing between the double-fiber pigtails is generally selected to be 125-250 um (the double-fiber pigtail is composed of a double-fiber capillary and two fibers, the connecting line distance between the centers of two holes in the double-fiber capillary is the spacing between the double-fiber pigtails), and the end faces of the double-fiber pigtails are polished by 8 degrees and plated with corresponding antireflection film layers; the transmission working distance between the two ends is generally 1-2 mm. If the coupling efficiency is to be guaranteed, theoretically, errors caused by packaging are not involved, and the structure is required to compensate the transverse deviation of 0.244mm at most and the axial angle deviation of 3.577 degrees at most at the working wavelength of 1550 nm; thus, the whole linearity degree of the device is reduced, and the specific structure is shown in figure 1; according to the data calculation, the transverse space plus the transverse space required by glue injection needs to be increased by 0.36mm at most; the diameter of the components at the two ends is 1.8mm, a small glass tube with the outer diameter of 2.78mm is used for inner packaging, and the components are assembled into a large glass tube with the inner diameter of 3.00mm and the length of 19mm to be packaged outside as much as possible by adjusting the space positions of the components at the two ends.

SUMMERY OF THE UTILITY MODEL

The utility model aims at overcoming the shortcoming among the above-mentioned prior art, providing an online three port fiber wavelength division multiplexer that the compact axiality that the performance is good, compact structure, encapsulation are accurate is high.

In order to achieve the above object, the compact type online three-port optical fiber wavelength division multiplexer with high coaxiality of the present invention has the following components:

the compact online three-port optical fiber wavelength division multiplexer with high coaxiality is mainly characterized in that the optical fiber wavelength division multiplexer comprises an input end double-optical-fiber tail fiber, an input end radial gradient self-focusing lens Glens, a wavelength division multiplexing optical filter, an output end radial gradient self-focusing lens Glens and an output end double-optical single tail fiber;

the first end face of the input end radial gradient self-focusing lens Glens is adjacent to the input end double-optical-fiber tail fiber, and the second end face of the input end radial gradient self-focusing lens Glens is adjacent to the wavelength division multiplexing optical filter;

the first end face of the output end radial gradient self-focusing lens Glens is arranged opposite to the wavelength division multiplexing optical filter, and the second end face of the output end radial gradient self-focusing lens Glens is adjacent to the output end double-optical single tail fiber;

the input end double-optical fiber pigtail comprises a first double-optical fiber capillary and two first optical fibers, wherein the two first optical fibers are respectively positioned in two holes of the first double-optical fiber capillary, and the two first optical fibers are respectively used as a common end and a reflection end of the optical fiber wavelength division multiplexer;

the output end double-optical single tail fiber comprises a second double-fiber capillary tube and a second optical fiber, the second optical fiber is positioned in one of two holes of the second double-fiber capillary tube, and the second optical fiber is used as a transmission end of the optical fiber wavelength division multiplexer.

Preferably, the diameter of the input end radial gradient self-focusing lens Glens is 1.0mm, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, the peripheral pitch is 0.248-0.249, and the first end face and the second end face of the input end radial gradient self-focusing lens Glens are 10.7 degrees and 0 degree respectively.

Preferably, the first end surface of the input end radial gradient self-focusing lens Glens is plated with an anti-reflection film layer, and the first end surface of the input end radial gradient self-focusing lens Glens is provided with a long platform of 0.1-0.2 mm.

Preferably, an end face of the input end dual-fiber pigtail adjacent to the input end radial gradient self-focusing lens Glens is 8.5 degrees, and an antireflection film layer is plated on an end face of the input end dual-fiber pigtail adjacent to the input end radial gradient self-focusing lens Glens.

More preferably, the transmission working distance between the wavelength division multiplexing filter and the first end face of the output end radial gradient self-focusing lens Glens is 0.4-0.5 mm.

Preferably, the diameter of the output-end radial gradient self-focusing lens Glens is 1.0mm, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, the peripheral pitch is 0.248-0.249, and the first end face and the second end face of the output-end radial gradient self-focusing lens Glens are 0 degree and 10.7 degrees respectively.

Preferably, the second end surface of the output end radial gradient self-focusing lens Glens is plated with an anti-reflection film layer, and the second end surface of the output end radial gradient self-focusing lens Glens is provided with a long platform of 0.1-0.2 mm.

Preferably, an end face of the single output-end dual-optical fiber pigtail adjacent to the output-end radially gradually-changing self-focusing lens Glens is 6.8 degrees, and an antireflection film layer is plated on an end face of the single output-end dual-optical fiber pigtail adjacent to the output-end radially gradually-changing self-focusing lens Glens.

Preferably, the outer side of the input end double-optical fiber pigtail and the outer side of the output end double-optical single pigtail are respectively sleeved with a fiber with the outer diameter of

A first glass tube with the length of 1.4 plus or minus 0.01mm and the length of 2.6 plus or minus 0.05 mm;

the outer side of the input end radial gradual change self-focusing lens Glens is sleeved with a lens with the outer diameter of

A second glass tube with the length of 1.4 plus or minus 0.01mm and the length of 2.2 plus or minus 0.05 mm;

the outer side of the output end radial gradient self-focusing lens Glens is sleeved with a lens with the outer diameter of

A third glass tube with the length of 1.4 plus or minus 0.01mm and the length of 2.4 plus or minus 0.05 mm;

the optical fiber wavelength division multiplexer also comprises a fourth glass tube, and the outer diameter of the fourth glass tube is

2.4 +/-0.01 mm and 13 +/-0.05 mm in length, and the fourth glass tube is sleeved outside the first glass tube, the second glass tube and the third glass tube.

Preferably, the diameters of the input end double-optical-fiber pigtail, the input end radial gradient self-focusing lens Glens, the wavelength division multiplexing optical filter, the output end radial gradient self-focusing lens Glens and the output end double-optical single-fiber pigtail are all 1.0 +/-0.05 mm;

the outer side of the input end double-optical fiber tail fiber and the outer side of the output end double-optical single-fiber tail fiber are respectively sleeved with a fiber sleeve with the outer diameter of

A first glass tube with a length of 1.2 plus or minus 0.01mm and a length of 2.6 plus or minus 0.05 mm;

2.2 +/-0.01 mm and 13 +/-0.05 mm in length, and the fourth glass tube is sleeved outside the two first glass tubes, the input end radial gradient self-focusing lens Glens, the wavelength division multiplexing optical filter and the output end radial gradient self-focusing lens Glens.

Preferably, the two-fiber pigtail at the input end and the lens Glens at the input end, the lens Glens at the input end and the wavelength division multiplexing optical filter, and the lens Glens at the output end and the single-fiber pigtail at the output end are all fixed by ultraviolet glue.

Preferably, a circular gasket is further disposed between the input end radial gradient auto-focusing lens Glens and the wavelength division multiplexing filter.

The compact online three-port optical fiber wavelength division multiplexer with high coaxiality in the embodiment has the advantages of small overall transverse offset, small overall axial angle deviation, high mode coupling efficiency, high coaxiality, strong linearity, high return loss, compact size and accurate packaging, and can be widely applied to the field of optical fiber communication.

Drawings

Fig. 1 is a schematic optical path diagram of a three-port optical fiber wavelength division multiplexer in the prior art.

Fig. 2 is a schematic optical path diagram of the compact high-coaxiality online three-port optical fiber wavelength division multiplexer according to an embodiment of the present invention.

Fig. 3 is a schematic diagram of an encapsulation structure of the compact high-coaxiality online three-port optical fiber wavelength division multiplexer according to an embodiment of the present invention.

Fig. 4 is a schematic diagram illustrating the transmission end ray tracing of the central ray of the compact high-coaxiality online three-port optical fiber wavelength division multiplexer according to an embodiment of the present invention through each surface.

Fig. 5 is a schematic diagram of a package structure of a compact high-coaxiality online three-port optical fiber wavelength division multiplexer according to another embodiment of the present invention.

Reference numerals

a1 input end double-fiber tail fiber

Glens of radial gradient self-focusing lens at input end of a2

a3 wave division multiplexing filter

Glens of radial gradient self-focusing lens at output end of a4

a5 output end double-optical single tail fiber

a6 first glass tube

a7 second glass tube

a8 third glass tube

a9 fourth glass tube

a10 reflective end

a11 transmissive end

a12 gasket

a13 dispensing

a14 common terminal

a15 single hole single fiber tail fiber

a16 input end focusing lens

a17 output end focusing lens

Detailed Description

In order to clearly understand the technical contents of the present invention, the following embodiments are specifically illustrated in detail.

As shown in fig. 2 to 4, the compact online three-port optical fiber wavelength division multiplexer with high coaxiality in this embodiment includes an input end dual-optical fiber pigtail a1, an input end radially graded self-focusing lens Glensa2, a wavelength division multiplexing optical filter a3, an output end radially graded self-focusing lens Glensa4, and an output end dual-optical single pigtail a 5;

the first end face of the input end radial gradient self-focusing lens Glensa2 is adjacent to the input end dual-optical fiber pigtail a1, and the second end face of the input end radial gradient self-focusing lens Glensa2 is adjacent to the wavelength division multiplexing optical filter a 3;

the first end face of the output end radial gradient self-focusing lens Glensa4 is arranged opposite to the wavelength division multiplexing optical filter a3, and the second end face of the output end radial gradient self-focusing lens Glensa4 is adjacent to the output end double-optical single tail fiber a 5;

the input end dual-fiber pigtail a1 comprises a first dual-fiber capillary and two first fibers, the two first fibers are respectively positioned in two holes of the first dual-fiber capillary, and the two first fibers are respectively used as a common end a14 and a reflection end a10 of the fiber wavelength division multiplexer;

the output end dual-optical single tail fiber a5 comprises a second dual-fiber capillary and a second optical fiber, the second optical fiber is positioned in one of two holes of the second dual-fiber capillary, and the second optical fiber is used as a transmission end a11 of the optical fiber wavelength division multiplexer.

The distance between two holes of the first double-fiber capillary in the input end double-fiber pigtail a1 is equal to the distance between two holes of the second double-fiber capillary in the output end double-fiber pigtail a 5.

In the embodiment, the diameter of the input end radial gradient self-focusing lens Glensa2 is 1.0mm, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, the peripheral pitch is 0.248-0.249, and the first end face and the second end face of the input end radial gradient self-focusing lens Glensa2 are respectively 10.7 degrees and 0 degree.

In this embodiment, the first end surface of the input end radial gradient self-focusing lens glena 2 is plated with an antireflection film layer, and the first end surface of the input end radial gradient self-focusing lens glena 2 is provided with a long platform of 0.1-0.2 mm.

In this embodiment, an end face of the input end dual-fiber pigtail a1 adjacent to the input end radially graded self-focusing lens glena 2 is 8.5 degrees, and an end face of the input end dual-fiber pigtail a1 adjacent to the input end radially graded self-focusing lens glena 2 is coated with an antireflection film layer.

In this embodiment, the transmission working distance between the wavelength division multiplexing filter a3 and the first end surface of the output end radially graded self-focusing lens Glens is 0.4-0.5 mm.

In this embodiment, the diameter of the output-end radial gradient self-focusing lens Glensa4 is 1.0mm, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, the peripheral pitch is 0.248-0.249, and the first end face and the second end face of the output-end radial gradient self-focusing lens Glensa4 are 0 degree and 10.7 degree respectively.

In this embodiment, the second end surface of the output end radial gradient self-focusing lens glena 4 is plated with an anti-reflection film layer, and the second end surface of the output end radial gradient self-focusing lens glena 4 has a long platform of 0.1-0.2 mm.

In this embodiment, an end face of the single output-end dual-optical pigtail a5 adjacent to the output-end radially graded self-focusing lens glena 4 is 6.8 degrees, and an end face of the single output-end dual-optical pigtail a5 adjacent to the output-end radially graded self-focusing lens glena 4 is coated with an antireflection film layer.

In this embodiment, the outer side of the input end dual-fiber pigtail a1 and the outer side of the output end dual-fiber pigtail a5 are respectively sleeved with a fiber assembly having an outer diameter of

A first glass tube a6 with the length of 1.4 plus or minus 0.01mm and 2.6 plus or minus 0.05 mm;

the outer side of the input end radial gradient self-focusing lens Glensa2 is sleeved with a lens with the outer diameter of

A second glass tube a7 with the length of 1.4 plus or minus 0.01mm and 2.2 plus or minus 0.05 mm;

the outer side of the output end radial gradient self-focusing lens Glensa4 is sleeved with a lens with the outer diameter of

A third glass tube a8 of 1.4/-0.01mm and a length of 2.4 ± 0.05 mm;

the optical fiber wavelength division multiplexer also comprises a fourth glass tube a9, and the outer diameter of the fourth glass tube a9 is

2.4 +/-0.01 mm and 13 +/-0.05 mm in length, and the fourth glass tube a9 is sleeved outside the first glass tube a6, the second glass tube a7 and the third glass tube a 8.

During manufacturing, two ends of the first glass tube a6, the second glass tube a7 and the third glass tube a8 are internally packaged, and the reliability of the wavelength division multiplexer is strengthened by performing permanent curing on epoxy resin glue. And the fourth glass tube a9 may be permanently cured by uv glue.

In this embodiment, the space between the input end dual-fiber pigtail a1 and the input end radial gradient self-focusing lens Glensa2, the space between the input end radial gradient self-focusing lens Glensa2 and the wavelength division multiplexing filter a3, and the space between the output end radial gradient self-focusing lens Glensa4 and the output end dual-fiber single pigtail a5 are all fixed by ultraviolet glue. The uv glue needs to cover the whole circle of gaps.

In other embodiments, the space between the input end dual-fiber pigtail a1 and the input end radial gradient self-focusing lens Glensa2, the space between the input end radial gradient self-focusing lens Glensa2 and the wavelength division multiplexing filter a3, and the space between the output end radial gradient self-focusing lens Glensa4 and the output end dual-fiber single pigtail a5 may also be fixed by epoxy resin glue. The thickness of the epoxy resin glue is 0.2mm, the width of the epoxy resin glue is at least 0.25mm, or the epoxy resin glue covers the whole open area.

In this embodiment, an annular gasket a12 is further disposed between the input end radially graded self-focusing lens Glens and the wavelength division multiplexing filter.

As shown in fig. 5, in another embodiment, the diameters of the input end dual-fiber pigtail, the input end radial gradient self-focusing lens Glens, the wavelength division multiplexing optical filter, the output end radial gradient self-focusing lens Glens and the output end dual-fiber single-fiber pigtail are all 1.0 ± 0.05 mm;

As can be seen from fig. 5, the optical fiber wavelength division multiplexer in this embodiment does not include the second glass tube and the third glass tube, and the size of the glass tubes is more compact, so that the structure of the optical fiber wavelength division multiplexer is more compact.

In this embodiment, the compact high-coaxiality online three-port optical fiber wavelength division multiplexer can be used in an optical path system with particularly strict space requirements, an optical fiber passive or active chassis or module. The method can be widely applied to the fields of optical network systems, multi-channel optical signal monitoring, optical switching connection systems, optical fiber debugging and measuring systems and the like.

The compact online three-terminal with high coaxiality in the embodimentThe optical element in the optical fiber wavelength division multiplexer is fixed not only by the glass tube, but also directly arranged on the optical element

1.0mm input end dual-fiber pigtail a1 and

a13 glue between 1.0mm input end radial gradient self-focusing lens Glensa2 and a glue directly arranged on

1.0mm output end radial gradient self-focusing lens Glensa4 and

and a13 glue is dispensed at the gap of the double-optical single tail fiber a5 at the output end of 1.0, wherein the glue is the position for fixing the ultraviolet glue.

The compact high-coaxiality online three-port optical fiber wavelength division multiplexer in this embodiment is further described with reference to fig. 2 and 3:

as shown in fig. 2 and 3, in the compact online three-port optical fiber wavelength division multiplexer with high coaxiality in this embodiment, by changing the manufacturing structure and manufacturing process of a single optical fiber collimator at one end thereof (i.e., the single optical fiber collimator is formed by an output-end radially graded self-focusing lens Glens and an output-end dual-optical single fiber pigtail together), the focusing lens uses a radially graded self-focusing lens Glens with a diameter of 1.0mm, the focusing constant of the output-end radially graded self-focusing lens Glensa4 is 0.596, the central refractive index is 1.590, the peripheral pitch is 0.249, one surface is a plane, the other surface is polished by 10.7 degrees and plated with a corresponding anti-reflection film layer, and a platform with a length of 0.2mm is provided; the structure of the single output-end double-optical tail fiber a5 is basically similar to that of the input-end double-optical fiber tail fiber a1, but the single output-end double-optical fiber tail fiber only comprises one optical fiber, namely the double-optical fiber tail fiber consists of a double-optical-fiber capillary and one optical fiber, only one hole in the double-optical-fiber capillary is used (used as a transmission end a 11), the end surface of the double-optical-fiber tail fiber is polished by 6.8 degrees to be plated with a corresponding antireflection film layer, and the pre-curing glue dispensing and permanent glue injecting position (namely an ultraviolet glue position is arranged, the pre-curing and the permanent curing of the point are realized by adopting ultraviolet glue, and the specific reference can be made to the glue dispensing position marked in figure 3) is changed into the position only at the gap between the focusing lens and the double-optical-; the radial gradient self-focusing lens of the double-fiber tail fiber and the wavelength division multiplexing filter plate at the other end is a lens with the same type specification, the peripheral pitch is 0.248-0.249, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, one surface is a plane, the other surface is polished by 10.7 degrees and plated with a corresponding anti-reflection film layer, and the other surface is provided with a 0.2mm long platform; the tail fiber uses a double-fiber tail fiber with the same distance with the other end, the double-fiber tail fiber consists of a double-fiber capillary and two fibers, two holes in the double-fiber capillary are used (used as a public end a14 and a reflection end a 10), and the end surface is polished by 8.5 degrees and plated with a corresponding antireflection film layer; the transmission working distance of two ends is generally 0.5mm, small glass tubes with the diameter of 1.4mm are added to tail fiber parts of the two ends for internal packaging, and large glass tubes with the inner diameter of 1.6mm, the outer diameter of 2.4mm and the length of 13mm are used for external packaging; the structure has higher reliability and is easier to pass a severe environment reliability test; the structure does not relate to errors brought by packaging under the condition of ensuring equal coupling efficiency according to theoretical calculation, only needs to compensate 0.0002mm transverse deviation and 0.02-degree axial angle deviation under the working wavelength of 1550nm, is higher in coaxiality and stronger in linearity.

The compact online three-port optical fiber wavelength division multiplexer with high coaxiality in the embodiment is free from errors caused by packaging by theoretical calculation under the condition of ensuring the coupling efficiency, only 0.0002mm of transverse deviation and 0.02-degree axial angle deviation need to be compensated by the structure under the working wavelength of 1550nm, the coaxiality is higher, the linearity is stronger, the size is compact, and the packaging precision can be widely applied to the field of optical fiber communication.

The compact high-coaxiality online three-port optical fiber wavelength division multiplexer in this embodiment is further analyzed as follows:

with the above optical design, the coupling efficiency of the three-port optical fiber wavelength division multiplexer in this embodiment is calculated as follows;

let the known transmission wavelength: 1550 nm; reflection wavelength: 1310 nm; the eigenmode field radii of the common end a14, transmission end a11 and reflection end a10 optical fibers are: 5.25um @1550nm, 4.6um @1310 nm; and is in a single mode propagation mode; the spacing between the two fiber pigtails is 0.2 mm. Thus, the device is provided with

1.0mm input end dual-fiber pigtail a1 and

the gap between the 1.0mm input end radial gradient self-focusing lens Glensa2 is controlled to be 0.007-0.010 mm;

the gap between the 1.0mm output end radial gradient self-focusing lens Glensa4 and the output end double-optical single tail fiber a5 is controlled to be 0.009-0.012 mm.

The compact online three-port optical fiber wavelength division multiplexer with high coaxiality has the following characteristics that the path of central light rays passing through the transmission ends a11 of each surface can be shown in fig. 4, and the central light ray tracing parameter data are shown in the following table 1:

surface number of light passing through	Distance of ray from optical axis (mm)	Angle of light and optical axis	Transmission medium for light beam entering
				0	0.0100	0.00	In an optical fiber
1	0.0100	-3.83	Into the air
				2	0.0997	1.64	Into Glens
3	0.0467	-5.44	Into the air
				4	0.0401	-3.77	Into quartz
5	-0.0125	-5.44	Into the air
				6	-0.0602	-3.42	Into Glens
7	-0.0996	-3.10	Into the air
				8	-0.0998	-0.02	Incoming optical fiber
9	-0.0998	-0.02	In an optical fiber

TABLE 1

The light beam is transmitted in a single mode in the optical fiber and is transformed in the optical element in a manner such that the radial beam intensity distribution is approximately gaussian and the beam is represented by a complex q parameter, in a manner that complies with the laws of the optical element transmission matrix A, B, C, D.

The beam variation parameters are shown in the following table 2:

TABLE 2

Performing the coupling efficiency calculation at the surface number 8 according to the above tables 1 and 2, wherein the state when the light beam reaches and enters the surface number 8 is that the light beam enters the surface of the optical fiber from the air; at the moment, under the condition that the light beam is approximate to a Gaussian light beam, the coupling between two Gaussian modes can be reduced; one is a gaussian beam 1 reaching and entering the surface number 8 and a gaussian beam 2 which is approximately parallel light and is linearly transmitted in a fundamental mode in the optical fiber; the two Gaussian beams are very close in beam waist, namely the wave surface curvature radiuses R1 and R2 are very large (R1 is-9819.81 um, and R2 is infinite), so that the two Gaussian beams have

Omega 1 is the spot radius size of 5.23um at surface number 8, omega 2 is the intrinsic mode field radius of 5.25um, theta is the angle of 0.02 degree (about 0.000349 radians) between the light ray at surface number 8 and the optical axis, and chi 0 is the transverse offset of-0.0002 mm at surface number 8 (the distance between the light ray at surface number 8 and the optical axis minus 0.1mm of the position of the optical fiber hole at surface number 8 and minus 0.0998mm is equal to-0.0002 mm); η is the normalized coupling efficiency, and the formula and the calculation result are as follows:

so the theoretical result η of the two gaussian mode coupling efficiency is 99.9978%.

The compact online three-port optical fiber wavelength division multiplexer with high coaxiality can be used as an 1550/1310nm online three-port optical fiber wavelength division multiplexing device. The transmission wavelength is 1550nm, the reflection wavelength is 1310nm, the optical fiber is a single mode optical fiber and SMF-

The distance between the Ultra optical fiber and the double optical fiber tail fiber is 0.2 mm.

The differences from the prior art can be seen in table 3 below:

TABLE 3

The compact online three-port optical fiber wavelength division multiplexer with high coaxiality in the embodiment has small overall transverse offset which can reach 0.0002mm, and the overall axial angle deviation can reach 0.02 degree. The optical elements, namely the input end double-optical-fiber pigtail a1, the input end radial gradient self-focusing lens Glensa2, the output end radial gradient self-focusing lens Glensa4 and the output end double-optical single pigtail a5 are freely aligned in space, so that the packaging is more accurate, and the overall light beam quality is indirectly improved. The reliability of the wavelength division multiplexer is enhanced by internally packaging two ends through the arrangement of the first glass tube a6, the second glass tube a7 and the third glass tube a8, and externally packaging through the arrangement of the fourth glass tube a 9. The physical packaging size of the whole online three-port optical fiber wavelength division multiplexing device is below 15mm, the whole compact online three-port optical fiber wavelength division multiplexing device with high coaxiality has small transverse offset, small axial angle deviation, high mode coupling efficiency, high coaxiality, strong linearity, high return loss, compact size and accurate packaging, and can be widely applied to the field of optical fiber communication.

In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims

1. The compact online three-port optical fiber wavelength division multiplexer with high coaxiality is characterized by comprising an input end double-optical-fiber tail fiber, an input end radial gradient self-focusing lens Glens, a wavelength division multiplexing optical filter, an output end radial gradient self-focusing lens Glens and an output end double-optical single optical-fiber tail fiber;

the first end face of the output end radial gradient self-focusing lens Glens is arranged opposite to the wavelength division multiplexing optical filter, and the second end face of the output end radial gradient self-focusing lens Glens is adjacent to the output end double-optical single fiber pigtail;

the output end double-optical single fiber pigtail comprises a second double-fiber capillary and a second optical fiber, wherein the second optical fiber is positioned in one of two holes of the second double-fiber capillary, and the second optical fiber is used as a transmission end of the optical fiber wavelength division multiplexer.

2. The compact high-coaxiality online three-port optical fiber wavelength division multiplexer according to claim 1, wherein the diameter of the input end radial gradient self-focusing lens Glens is 1.0mm, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, the peripheral pitch is 0.248-0.249, and the first end face and the second end face of the input end radial gradient self-focusing lens Glens are respectively 10.7 degrees and 0 degree.

3. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 2, wherein the first end face of the input end radial gradient self-focusing lens Glens is coated with an antireflection film layer, and the first end face of the input end radial gradient self-focusing lens Glens has a long platform of 0.1-0.2 mm.

4. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 1, wherein an end face of the input end dual-fiber pigtail adjacent to the input end radially graded self-focusing lens Glens is 8.5 degrees, and an end face of the input end dual-fiber pigtail adjacent to the input end radially graded self-focusing lens Glens is coated with an anti-reflection film layer.

5. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 4, wherein the transmission working distance between the wavelength division multiplexing filter and the first end face of the output end radial gradient self-focusing lens Glens is 0.4-0.5 mm.

6. The compact high-coaxiality online three-port optical fiber wavelength division multiplexer according to claim 1, wherein the diameter of the output-end radially graded self-focusing lens Glens is 1.0mm, the focusing constant is 0.5962@1550nm, the central refractive index is 1.590@1550nm, the peripheral pitch is 0.248-0.249, and the first end face and the second end face of the output-end radially graded self-focusing lens Glens are 0 degree and 10.7 degrees respectively.

7. The compact on-line three-port optical fiber wavelength division multiplexer according to claim 6, wherein the second end surface of the output end radial gradient self-focusing lens Glens is coated with an anti-reflection film layer, and the second end surface of the output end radial gradient self-focusing lens Glens has a long platform of 0.1-0.2 mm.

8. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 1, wherein an end face of the output-end dual-optical-fiber single tail fiber adjacent to the output-end radially-graded self-focusing lens Glens is 6.8 degrees, and an end face of the output-end dual-optical-fiber single tail fiber adjacent to the output-end radially-graded self-focusing lens Glens is coated with an antireflection film layer.

9. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 1, wherein an outer side of the input-end dual-fiber pigtail and an outer side of the output-end dual-fiber single-fiber pigtail are respectively sleeved with a fiber having an outer diameter of

A first glass tube with a length of 2.6 mm plus or minus 0.05 mm;

A second glass tube with the length of 2.2 mm plus or minus 0.05 mm;

A third glass tube with the length of 2.4 +/-0.05 mm;

The length is 13 +/-0.05 mm, and the fourth glass tube is sleeved outside the first glass tube, the second glass tube and the third glass tube.

10. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 1, wherein diameters of the input end dual-fiber pigtail, the input end radial gradient self-focusing lens Glens, the wavelength division multiplexing optical filter, the output end radial gradient self-focusing lens Glens and the output end dual-fiber single fiber pigtail are all 1.0 ± 0.05 mm;

A first glass tube with a length of 2.6 mm plus or minus 0.05 mm;

The length of the glass tube is 13 +/-0.05 mm, and the fourth glass tube is sleeved on the outer sides of the two first glass tubes, the input end radial gradient self-focusing lens Glens, the wavelength division multiplexing optical filter and the output end radial gradient self-focusing lens Glens.

11. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 1, wherein the input end dual-fiber pigtail and the input end radially graded self-focusing lens Glens, the input end radially graded self-focusing lens Glens and the wavelength division multiplexing filter, and the output end radially graded self-focusing lens Glens and the output end dual-fiber single fiber pigtail are fixed by ultraviolet glue.

12. The compact high-coaxiality online three-port fiber wavelength division multiplexer according to claim 1, wherein an annular gasket is further disposed between the input end radially graded self-focusing lens Glens and the wavelength division multiplexing filter.