JP3229142B2 - Optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical device using a holding member for connecting an optical fiber, and more particularly to an optical device in which an optical fiber is connected to an optical component such as a collimator lens or a polarizing glass.

[0002]

2. Description of the Related Art Hitherto, in the field of optical devices for performing optical measurement, optical sensing or optical communication, optical components such as optical waveguide components, laser semiconductors, collimators, isolators, acousto-optic modulators, and polarizers have been used. You. An optical fiber for light propagation is coupled to these optical components in the optical device. When, for example, a polarization maintaining fiber is coupled to the optical component as the optical fiber, the end face of the input or output portion of the polarization maintaining fiber is coupled so that its polarization axis coincides with the polarization axis of the optical component. Need to be done.
Note that the end face of the coupling part of the optical component and the end face of the polarization maintaining fiber may be formed perpendicularly to the optical axis or may be formed obliquely.

In such an optical device for coupling an optical component to an optical fiber, insertion loss, reflection loss,
Crosstalk and the like affect its performance. Therefore, in order to maintain the performance of the optical device, it is important to couple the optical component and the optical fiber well.

FIG. 13 is a plan view showing an example of an optical waveguide component in which optical fibers are connected by a conventional method. A core 71a is formed on the optical waveguide surface 71 of the optical waveguide component 70. An adhesive 7 is provided on both end surfaces of the optical waveguide surface 71, respectively.
The optical fibers 72 and 73 are coupled via the elements 6 and 77. At this time, each of the joining ends 72 of the optical fibers 72, 73
Capillaries 74 and 75 are attached to the end portions a and 73a, respectively.
And the end face of the capillary 75 coincide with the end face of the joint 73a. Further, protective members 70a and 70b are attached to both ends of the optical waveguide surface 71, and the respective end surfaces are joined to the end surfaces of the capillaries 74 and 75 via adhesives 76 and 77, respectively.

FIG. 14 is a diagram showing a method of connecting an optical fiber to the optical waveguide surface 71 of FIG. Here, the protection members 70a and 70b are omitted. Optical fiber 73
Is a kind of panda fiber, for example, a kind of polarization maintaining fiber. The capillary 75 is made of ceramics. The joint portion 73a of the optical fiber 73 is inserted into a small hole 75a formed in a cylindrical capillary 75, and is fixed to the small hole 75a with an adhesive (not shown).

The end face 73b of the optical fiber 73 is aligned with the end face of the core 71a such that the optical axis coincides with the Z axis. FIG. 15 is an enlarged view of the end face 73b of the optical fiber 73 of FIG. In order to match the end face 73b of the optical fiber 73 with the end face of the core 71a of the optical waveguide face 71, for example, a line connecting the core 73c and the centers of the stress applying members 73d and 73e in the optical fiber 73 coincides with the Y axis. To do. At the same time, the worker measures the output energy of the optical waveguide surface 71. Then, the optical fiber 73 is set to X, so that the output energy of the optical waveguide surface 71 becomes closest to the output energy of the optical fiber 73 measured in advance.
The joining is performed while finely adjusting the angle θz about the three axes of Y and Z and about the Z axis.

On the other hand, as an optical device, there is a collimator in addition to the above. FIG. 16 is a diagram showing a schematic configuration of a conventional collimator. The collimator 81 is a polarizing fiber collimator used for an optical sensor or the like. An optical fiber 85 is connected to a capillary 82 as an optical connector. Further, between the capillary 82 and the collimator lens 83, a laminated polarizer 84 is sandwiched and fixed.
Such a collimator 81 polarizes the light emitted from the optical fiber 85 with the laminated polarizer 84, and outputs the light in parallel by the collimator lens 83.

In general, a polarizing fiber collimator using an optical fiber has higher performance if a polarizing element is provided behind the collimating lens. This is a laminated polarizer 8
Since the polarization elements such as 4 have the incident angle dependence of the light on the crosstalk (degree of polarization), the polarization element has passed through the collimating lens 83 more than the light that has spread according to the numerical aperture NA of the optical fiber 85. This is because the parallel light can increase the crosstalk and increase the linear polarization.

[0009]

However, in the former optical waveguide component, since the conventional capillaries 74 and 75 are cylindrical, their orientations around their axes cannot be specified. The polarization axis directions of 72 and 73 could not be visually confirmed. For this reason, when it is necessary to make the polarization axes coincide with each other or to couple the polarization axes at a specific angle, as in the case of the optical waveguide component 70 and the optical fibers 72 and 73, it is complicated and difficult. However, there is a problem that the work takes time.

In the latter collimator, the laminated polarizer 84 has a small effective diameter of several hundred μm and a small thickness of several tens μm due to cost and manufacturing problems. Also, the mechanical strength is weak. When the laminated polarizer 84 is used for a collimator, a structure in which the laminated polarizer 84 is directly attached to the end face of the fiber has to be adopted because the effective diameter is small. The reason for this is that the light emitted from the optical fiber 85 has a spread, so that light cannot be transmitted efficiently with low loss unless it is directly attached to the end face of the fiber. This is because sufficient crosstalk cannot be increased.

Further, in the case of a structure in which the laminated polarizer 84 is directly attached to the end face of the fiber, the following disadvantages also occur. That is, to increase the return loss, the optical fiber 85
It is necessary to make the end face slanting, but in this case, since the polarization characteristic depends on the incident angle, crosstalk is reduced. The optical fiber 85 and the laminated polarizer 84
It is difficult to bond and fix the polarization axes of the above.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical device which can easily and precisely couple an optical component and an optical fiber.

Another object of the present invention is to provide an optical device in which a collimating lens is used as an optical component, which has high performance and high design flexibility.

[0014]

According to the present invention, in order to solve the above-mentioned problems, in an optical device using an optical fiber,
An optical fiber, a polarizing glass for polarizing light from the optical fiber, and a collimating lens for converting light from the polarizing glass to collimated light, and attached to an end of the optical fiber, the light A holding member on which a reference surface indicating the direction of the polarization axis of the light propagating through the fiber is formed; and a shape portion into which the reference surface of the holding member fits.
And a spacer to which the polarizing glass is bonded.
The reference surface and the shape portion are fitted to each other.
The optical fiber and the polarizing glass are separated by a predetermined distance,
Polarization axis of light propagating through the optical fiber and the polarizing glass
Are provided so that the polarization axes of the optical devices coincide with each other .

An optical device using an optical fiber includes an optical fiber, a collimating lens for converting light from the optical fiber into collimated light, and a polarizing glass for polarizing light from the collimating lens. A holding member attached to an end of the optical fiber and having a reference surface indicating a direction of a polarization axis of light propagating through the optical fiber, wherein the optical fiber and the collimating lens are separated by a predetermined distance. are connected to have your, polarizing glass and the optical fiber is connected to the polarization axes coincide, the shaped portion of the reference surface of the holding member is fitted
Having a spacer having the reference surface and the shape portion
By mating, the optical fiber and the polarizing glass are
At a fixed distance, the polarization axis of light propagating through the optical fiber
And the polarization axes of the polarizing glass are matched.
Optical apparatus characterized by that it is provided.

[0016]

The direction of the polarization axis of the light propagating through the optical fiber can be confirmed by the reference plane formed on the holding member attached to the end of the optical fiber. It is possible that the polarization axis of the light propagating through the fiber always has a predetermined angle relationship.

In addition, since the optical component includes a collimating lens for converting light emitted from the optical fiber into collimated light and a polarizing glass for polarizing the light, the effective diameter of the polarizing glass is as large as several tens mm. Since the thickness is several mm or more and the mechanical strength is large, the diameter can be made very large as compared with the conventional laminated polarizer. Thereby, it can be installed at a position away from the emission end face of the optical fiber. Therefore, the polarization axis alignment and assembly are facilitated. Further, since the return loss and the crosstalk can be increased, a high-performance optical device can be obtained.

[0018]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view showing a schematic configuration of an optical waveguide component according to a first reference example of the present invention. FIG. 3 is a cross-sectional view of the optical waveguide component of FIG. 2 along the longitudinal direction. The substrate 10a of the optical waveguide component 10 is formed of, for example, Z-cut lithium tantalate (LiTaO ₃ ).
The optical waveguide surface 11 is formed on Oa by proton exchange. The core 11a on the optical waveguide surface 11 has a polarization dependency of propagating only TM light. In addition, this ginseng
Optical waveguide circuit of the considered example is the Mach-Zehnder optical interferometer.

Protective members 10b and 10c are adhered to the upper surfaces of both ends of the optical waveguide surface 11. The left end face of the protection member 10b in the drawing and the right end face of the protection member 10c in the drawing are provided on the same plane as the respective end faces of the optical waveguide surface 11 and the substrate 10a. The end faces of the capillaries 14 and 15 are bonded to these end faces via adhesives 16 and 17, respectively. here,
The adhesives 16 and 17 are applied to the core 11 a and the optical fiber 1.
An optical adhesive whose refractive index is matched with each of the cores 2 and 13. Each of the capillaries 14 and 15 has an optical fiber 1
The cores 2 and 13 are attached, and each core is joined to the core 11a of the optical waveguide surface 11 by the structure and procedure described later.

On the other hand, the lower surface 10d of the substrate 10a is formed in a plane substantially parallel to the optical waveguide surface 11, and the lower surface 10d is used as a reference surface on the optical waveguide component 10 side. FIGS. 1A and 1B are diagrams showing a configuration of a capillary 15, wherein FIG. 1A is a perspective view and FIG. 1B is a perspective view showing a state where an optical fiber is inserted. The entire capillary 15 is formed by forming a planar cutout surface 15b on a cylindrical body formed of, for example, glass. This notched surface 15b
Are formed as alignment reference surfaces described later. The thickness of the cutout surface 15b is preferably about 0.2 mm when the diameter of the capillary 15 before forming the cutout surface 15b is 1.8 mm. Capillary 1
5 has a pore 15a formed along the axis. The connection end 13a of the optical fiber 13 is inserted into the small hole 15a, and is fixed by an adhesive (not shown). Here, the optical fiber 13 is, for example, a kind of panda fiber of a polarization maintaining fiber, and is inserted and fixed in the small hole 15a so that the polarization axis is perpendicular or parallel to the cutout surface 15b. Also, the end face 13 of the optical fiber 13
b is inserted and fixed so as to be on the same plane as the end face 15c of the capillary 15.

The capillary 14 and the optical fiber 1
The configuration of 2 is almost the same as the capillary 15 and the optical fiber 13, respectively, and the description is omitted here. Next, a procedure for connecting the optical fiber 13 and the capillary 15 having such a configuration to the optical waveguide component 10 will be described.

FIG. 4 shows the optical fiber 1 to the optical waveguide component 10.
FIG. 3 is a diagram illustrating a connection procedure between the capillary 3 and the capillary 15. Here, the protection members 10b and 10c are omitted. FIG. 5 is an enlarged view of the end face 13 b of the optical fiber 13. The optical fiber 13 is formed, for example, such that a line connecting the centers of the core 13c and the stress applying members 13d and 13e in the optical fiber 13 is perpendicular to the cutout surface 15b.
5 and is fixed.

When such an optical fiber 13 is connected to the end face of the core 11a, the optical axis of the
The end face 13b is aligned with the core 11a so as to coincide with the axial direction.
Align with the end face of Then, the worker can check the optical waveguide surface 11.
The output energy from the upper core 11a is measured, and the optical fiber 13 is finely adjusted in the X-axis and Y-axis directions so that the output energy is closest to the output energy of the optical fiber 13 measured in advance. At this time, the operator ensures that the cutout surface 15b of the capillary 15 is always parallel to the lower surface 10d of the substrate 10a. Thereby, the polarization axis of the optical fiber 13 is always kept in a fixed direction,
It is not necessary to finely adjust the optical fiber 13 with respect to the angle θz about the Z axis. Therefore, the polarization axis of the optical fiber 13 and the polarization axis of the optical waveguide surface 11 can be accurately and easily adjusted.

The capillary 14 and the optical fiber 1
2 can be connected to the optical waveguide component 10 by the same procedure. The inventors of the present invention have conducted experiments on such capillaries 14 and 15. As a result, when the optical waveguide surface 11 is a polarization-dependent single-mode optical waveguide having a wavelength of 633 nm, the axial misalignment loss is an average of 0.6% in total of input and output.
8 dB and the crosstalk was 30 dB or more. Therefore, the X-axis and Y-axis alignment accuracy is +/- 0.6 μm or less, and the θz alignment accuracy is +/- 2 ° or less. These values are almost the same as those in the case where the conventional capillary is used, and the connection work time is greatly reduced while maintaining the alignment accuracy as in the conventional case.

[0025] In the present embodiment, the optical fiber 12,1
Although an example in which 3 is a panda fiber has been described, the present invention is not limited to this and can be applied to other polarization maintaining fibers such as an elliptical core fiber and an elliptical jacket fiber.

[0026] In addition, in the present embodiment, the optical fiber 12,
Although the example in which 13 is a polarization maintaining fiber is shown, the invention is not limited to this, and the present invention can be applied to a single mode optical fiber in which two independent modes polarized in two directions orthogonal to each other in the fiber cross section propagate.

Further, in the present embodiment, although the core 11a of the optical waveguide face 11 shows an example having a polarization dependency which propagates only TM light, without being limited thereto, perpendicular with the optical waveguide core sectional The present invention can be applied to a single mode optical fiber in which two independent modes polarized in two directions propagate.

[0028] Next will be described a second exemplary embodiment of the present invention. FIG. 6 is a plan view showing a schematic configuration of an optical waveguide component according to a second reference example of the present invention. The substrate 20a of the optical waveguide component 20 includes:
For example, Z-cut lithium tantalate (LiTaO3
The optical waveguide surface 21 is formed on the substrate 20a by proton exchange. The core 21a of the optical waveguide surface 21 has a polarization dependency of propagating only TM light. The optical waveguide circuit of this reference example is
This is a Mach-Zehnder type optical interference circuit.

As shown in the drawing, both ends of the optical waveguide component 20 are formed obliquely. Protective members 20b and 20c are adhered to the upper surfaces of both ends of the optical waveguide surface 21.
The left end surface of the protection member 20b in the drawing and the protection member 20c
The right end face in the figure is formed obliquely like the optical waveguide component 20, and the optical waveguide face 21 and the substrate 20 are respectively formed.
It is provided so as to be on the same plane as each end face of a.
Then, adhesives 26 and 27 are respectively attached to these end faces.
The end faces of the capillaries 24 and 25 are joined via the. In this case, the end faces of the capillaries 24 and 25 are formed obliquely at an angle that matches the end face of the optical waveguide component 20. Here, the adhesives 26 and 27 are optical adhesives whose refractive indexes are matched with the cores 21a and the cores of the optical fibers 22 and 23. Optical fibers 22 and 23 are attached to the capillaries 24 and 25, respectively, and each core is connected to the core 2 of the optical waveguide surface 21 by the structure and procedure described later.
1a.

On the other hand, the lower surface (not shown) of the substrate 20a is formed in a plane substantially parallel to the optical waveguide surface 21, and this lower surface is used as a reference surface on the optical waveguide component 20 side. FIG. 7 is a diagram showing a configuration of the capillary 24,
(A) is a perspective view, (B) is a perspective view showing a state where an optical fiber is inserted. The entire capillary 24 is formed by forming a planar cutout surface 24b on a cylindrical body formed of, for example, glass. The cutout surface 24b is formed as a reference surface for alignment. The thickness of the notch surface 24b is
When the diameter of the capillary 24 before forming is 1.8 mm, it is preferably about 0.2 mm.

The end face 24c of the capillary 24 is polished so as to be inclined by an angle α with respect to the XY plane, for example, when the optical axis of the optical fiber 22 is aligned with the Z axis. The angle α is set in a range where the optical axis of the optical waveguide component 20 and the optical axis of the optical fiber 22 can be optically connected. Further, the capillary 24 has a pore 24a formed along the optical axis. The connection end 22a of the optical fiber 22 is inserted into the small hole 24a, and is fixed by an adhesive (not shown). Here, the optical fiber 22 is, for example, a kind of panda fiber of a polarization maintaining fiber, and is inserted and fixed in the pore 24a such that the polarization axis is perpendicular or parallel to the cutout surface 24b. The end face 22b of the optical fiber 22 is formed so as to be substantially flush with the end face 24c of the capillary 24, and is inserted and fixed.

After the optical fiber 22 is inserted into the pore 24a of the capillary 24 in advance, the end faces 24c and 22b
May be simultaneously formed to form an inclination.

The capillary 25 and the optical fiber 2
The configuration of No. 3 is almost the same as the capillary 24 and the optical fiber 22, respectively, and the description is omitted here. The capillary 24 having such a configuration is connected to the end face of the optical waveguide component 20 in substantially the same procedure as in the first embodiment described with reference to FIGS. That is, the output energy of the optical waveguide surface 21 is measured, and the optical fiber 22 is finely adjusted in the X-axis and Y-axis directions so that the output energy is closest to the previously measured output energy of the optical fiber 22. The cutout surface 24b of the capillary 24 is always parallel to the lower surface (not shown) of the optical waveguide surface 21.

As a result, the polarization axis of the optical fiber 22 is always kept in a fixed direction, so that the optical fiber 22 does not need to be finely adjusted with respect to the angle θz about the Z axis. Therefore, the polarization axis of the optical fiber 22 and the polarization axis of the optical waveguide surface 21 can be accurately and easily adjusted. Also book
In the reference example, the end faces of the capillary 24 and the optical fiber 22 are inclined at an angle α in accordance with the end face of the optical waveguide component 20, so that the return loss is increased and the connection with the optical waveguide component 20 is good. Can be

The capillary 25 and the optical fiber 2
3 can be connected to the optical waveguide component 20 by the same procedure. The present inventor conducted experiments on such capillaries 24 and 25. As a result, when the optical waveguide surface 21 was a polarization-dependent single mode optical waveguide having a wavelength of 633 nm, the axial misalignment loss was substantially the same as that of the first reference example. 0.68 dB on average with total output, 3 crosstalk
0 dB or more. Therefore, the X-axis and Y-axis alignment accuracy is +/- 0.6 μm or less, and the θz alignment accuracy is +/- 2 ° or less. These values are almost the same as those in the case where the conventional capillary is used, and the connection work time is greatly reduced while maintaining the alignment accuracy as in the conventional case.

[0036] In the present embodiment, the optical fiber 22, 24, 32
Although an example in which 3 is a panda fiber has been described, the present invention is not limited to this and can be applied to other polarization maintaining fibers such as an elliptical core fiber and an elliptical jacket fiber.

[0037] In addition, in the present embodiment, the optical fiber 22,
Although the example in which the polarization maintaining fiber 23 is used has been described, the present invention is not limited to this, and the present invention is also applicable to a single mode optical fiber in which two independent modes polarized in two directions orthogonal to each other in the fiber cross section propagate.

Further, in the present embodiment, although the core 21a of the optical waveguide face 21 shows an example having a polarization dependency which propagates only TM light, without being limited thereto, perpendicular with the optical waveguide core sectional The present invention can be applied to a single mode optical fiber in which two independent modes polarized in two directions propagate.

[0039] In addition, in the present reference example, the capillary 24,2
5 shows an example in which the end face is formed obliquely at an angle that coincides with the end face of the optical waveguide component 20, but the present invention is not limited to this, and the relationship between the refractive indices of the optical waveguide component 20, and the optical fibers 22, 23 is shown. May be formed at an appropriate angle.

Next, a description will be given of a third exemplary embodiment of the present invention.
FIG. 8 is a side sectional view showing a configuration of a collimator according to a third reference example of the present invention. The outer shape of the collimator 30 is formed by a cylindrical ferrule 31. A circular polarizing lens 32 is provided on the emission side in the ferrule 31. The polarizing lens 32 is obtained by forming needle-shaped metal fine particles arranged in one direction inside, and giving a polarizing glass having polarization characteristics to a lens shape. This allows
The polarizing lens 32 is used to control the divergent light 3 emitted from the optical fiber.
7 is collimated into parallel light, and only one of TM light and TE light is polarized.

In front of the polarizing lens 32 in the ferrule 31, a glass capillary 33 is inserted and fixed. The entire capillary 33 is formed by forming a cutout surface 33b in a cylindrical shape having a diameter substantially equal to the inner diameter of the ferrule 31. Further, the capillary 33 has a fine hole 33a formed along the axis. The cladding 34a of the optical fiber 34 is inserted into the pore 33a with its coating 34b peeled off and fixed with an adhesive (not shown). Here, the optical fiber 34 is, for example, a kind of panda fiber of a polarization maintaining fiber, and is inserted and fixed in the pore 33 a so that the polarization axis is perpendicular or parallel to the cutout surface 33 b. It is made to coincide with the polarization axis.

A base member 36 is provided in the ferrule 31. The base member 36 is formed with a flat base surface 36a so that when the capillary 33 is inserted into the ferrule 31, the capillary 33 can be fitted between the inner wall of the ferrule 31 and the base surface 36a. Has become.

With this configuration, when the optical fiber 34 is connected to the ferrule 31, the clad 34 at the tip of the optical fiber 34 is oriented so as to be in the direction of the above-mentioned polarization axis.
a is inserted into the capillary 33 and fixed, and the capillary 33 is inserted into the ferrule 31 and fixed with the adhesive 35. At this time, the direction of the cutout surface 33 b of the capillary 33 is made to coincide with the direction of the base surface 36 a of the base member 36. Thereby, the capillary 33 can be easily connected to the ferrule 3.
1 so that the polarization axis of the optical fiber 34 and the polarization axis of the polarizing lens 32 can be matched.

According to the experiment performed by the inventor of the present invention, the optical fiber 3
When a panda fiber for wavelength 1550 nm is used for 4, the insertion loss is 1 dB or less, and the crosstalk of the emitted light is 4
The return loss was 5 dB or more and the return loss was 20 dB or more.

[0045] In the present embodiment, although an example of using the panda fiber as the optical fiber 34, it is not limited thereto, in other polarization maintaining fiber such as elliptic core fiber and elliptic jacket fiber Good.

[0046] Further, in the present embodiment, an example of the optical fiber 34 and the polarization maintaining fiber, not limited thereto, has two modes independent of the polarization in two directions orthogonal in the fiber cross-section propagation To a single mode optical fiber.

Further, in the present embodiment, the circular polarized lenses 3
Although 2, a rectangular or square polarizing lens can be used. Furthermore, in the present embodiment, although using the polarizing lens 32 as a means for emitting collimated light, even with a polarization independent optical isolator using polarization glasses, polarized axis and polarization-dependent optical Panda fiber The polarization axis of the isolator can be easily adjusted. Therefore, an optical isolator with a fiber can be easily manufactured.

[0048] Next will be described a fourth exemplary embodiment of the present invention. Figure 9 is a side sectional view showing a fourth collimator configuration of the reference example of the present invention. The collimator 40 is a cylindrical ferrule 4
1 forms the outer shape. A circular polarizing lens 42 is provided on the emission side in the ferrule 41.
The polarizing lens 42 is obtained by forming needle-like metal fine particles arranged in one direction inside, and giving a polarizing glass having polarization characteristics a lens shape. As a result, the polarizing lens 42 collimates the divergent light 47 emitted from the optical fiber into parallel light, and polarizes only one of the TM light and the TE light.

In front of the polarizing lens 42 in the ferrule 41, a glass capillary 43 is inserted and fixed. The entirety of the capillary 43 is formed by forming a cutout surface 43b in a cylindrical shape having a diameter substantially equal to the inner diameter of the ferrule 41. Further, the capillary 43 has a pore 43a formed along the axis. The cladding 44a of the optical fiber 44 is inserted into the pore 43a with its coating 44b peeled off, and is fixed with an adhesive (not shown). Here, the optical fiber 44 is, for example, a kind of panda fiber of a polarization maintaining fiber, and is inserted and fixed in the pore 43a so that the polarization axis is perpendicular or parallel to the cutout surface 43b.
It is made to coincide with the polarization axis of the polarizing lens 42.

The end face 43 c of the capillary 43 is at a predetermined angle θα (for example, 8 °) with respect to a plane parallel to the polarizing lens 42.
It is polished so as to be inclined only. This polishing,
It may be before or after the optical fiber 44 is inserted and fixed in the pore 43a.

In the ferrule 41, a base member 46 is provided. A flat base surface 46a is formed on the base member 46. When the capillary 43 is inserted into the ferrule 41, the capillary 43 can be fitted between the inner wall of the ferrule 41 and the base surface 46a. ing.

With such a configuration, when the optical fiber 44 is connected to the ferrule 41, the clad 44 at the tip of the optical fiber 44 is oriented so as to be in the direction of the above-mentioned polarization axis.
a is inserted into the capillary 43 and fixed, and the capillary 43 is inserted into the ferrule 41 and fixed with the adhesive 45. At this time, the direction of the cutout surface 43 b of the capillary 43 is made to coincide with the direction of the base surface 46 a of the base member 46. Thereby, the capillary 43 can be easily connected to the ferrule 4.
1 so that the polarization axis of the optical fiber 44 and the polarization axis of the polarizing lens 42 can be matched.

According to the experiment of the inventor of the present application, the optical fiber 4
When a panda fiber for wavelength 1550 nm is used for 4, the insertion loss is 1 dB or less, and the crosstalk of the emitted light is 4
It was 5 dB or more. Further, the return loss was 40 dB or more, which was better than that of the third reference example.

[0054] In the present embodiment, although an example of using the panda fiber as the optical fiber 44, it is not limited thereto, in other polarization maintaining fiber such as elliptic core fiber and elliptic jacket fiber Good.

[0055] Further, in the present embodiment, an example of the optical fiber 44 and the polarization maintaining fiber, not limited thereto, has two modes independent of the polarization in two directions orthogonal in the fiber cross-section propagation To a single mode optical fiber.

[0056] In the present embodiment, the circular polarized lenses 4
Although 2, a rectangular or square polarizing lens can be used. Next, a first embodiment of the present invention will be described.

FIG. 10 is a side sectional view showing the structure of the collimator according to the first embodiment of the present invention. The outer shape of the collimator 50 is formed by a substantially cylindrical ferrule 51. On the emission side in the ferrule 51, a collimating lens 52 is provided. A polarizing glass 53 is provided in front of the collimating lens 52. The polarizing glass 53 has a predetermined aspect ratio by performing a process including a stretching process on a glass material mixed with raw material fine particles containing a metal element, and needle-like metal fine particles whose longitudinal direction is arranged in one direction. Is formed inside to impart polarization characteristics.

In front of the polarizing glass 53, a spacer 54 is provided.
A glass capillary 55 is inserted through the ferrule 51 and is fixed in the ferrule 51 by an adhesive 57. The capillary 55 is generally formed by forming a cutout surface 55 a in a cylindrical shape having substantially the same size as the inner wall of the ferrule 51.

The polarizing glass 53, the spacer 54 and the capillary 55 are integrally mounted. FIG. 11 is a diagram showing the configuration and coupling relationship of the polarizing glass 53, the spacer 54, and the capillary 55. A protruding piece 54 is provided before and after a cylindrical main body 54a in which a hole 54d is formed.
b, 54c are formed. The length obtained by adding the length of the main body 54a in the axial direction and the length of the protruding piece 54c is designed to be the focal length of the collimator lens 52. The projecting pieces 54b and 54c have upper surfaces formed with the same curvature as the inner wall of the ferrule 51. The lower surface of the projecting piece 54b is formed so as to be able to be joined to the cutout surface 55a of the capillary 55. The projecting piece 54c is formed to have a length substantially equal to the thickness of the polarizing glass 53.

The capillary 55 has fine holes 55 along the axis.
b is formed. The distal end of the optical fiber 56 is inserted into the small hole 55b, and is fixed with an adhesive (not shown). Here, the optical fiber 56 is, for example, a kind of panda fiber of a polarization maintaining fiber, and is inserted and fixed in the small hole 55b so that the polarization axis is perpendicular or parallel to the cutout surface 55a. And the axis of polarization.

In the collimator 50 having such a configuration, in order to match the polarization axis of the optical fiber 56 with the polarization axis of the polarizing glass 53, the tip of the optical fiber 56 is inserted.
The notched surface 55a of the fixed capillary 55 is aligned with the lower surface of the projecting piece 54b of the spacer 54, and the two are joined with an adhesive or the like. The polarizing glass 53 is bonded to the surface of the spacer 54 on the side of the protruding piece 54c.
Then, the optical fiber 56, the capillary 55, the spacer 54, and the polarizing glass 53 are inserted into the ferrule 51 in a state of being integrated, and as shown in FIG.
Are fixed by the adhesive 57 at the position where they contact the collimating lens 52.

As described above, in this embodiment, the spacer 54
, The polarization glass 53 and the optical fiber 56 fixed to the capillary 55 are connected, so that the polarization axis of the polarization glass 53 and the polarization axis of the optical fiber 56 can be easily matched. . Further, the distance between the end face 56 a of the optical fiber 56 and the collimator lens 52 can be automatically adjusted to the focal length of the collimator lens 52. Therefore, the coupling efficiency is improved.

According to the experiment of the present inventor, the wavelength 1550
When an optical fiber 56 (panda fiber), a polarizing glass 53, and a collimating lens 52 for nm are used, the insertion loss is 1 dB or less, the crosstalk is 45 dB or more, the return loss is 20 dB or more, and the emission beam shape is 0.6 mm or less. Polarized light and parallel light could be obtained.

In this embodiment, an example is shown in which a panda fiber is used as the optical fiber 56. However, the present invention is not limited to this, and other polarization maintaining fibers such as an elliptical core fiber and an elliptical jacket fiber may be used. Good.

Further, in this embodiment, an example is shown in which the optical fiber 56 is a polarization maintaining fiber. However, the present invention is not limited to this, and two independent modes polarized in two directions perpendicular to each other in the fiber cross section are propagated. To a single mode optical fiber.

Further, when the end face 55c of the capillary 55 and the end face 56a of the optical fiber 56 are polished so as to be inclined about 8 ° in the axial direction from the state shown in FIG.
dB or more.

Further, behind the collimating lens 52,
If a wavelength plate that can be manually adjusted is provided, the polarization direction of light emitted from the collimator lens 52 can be changed to an arbitrary state.

[0068] Next, a second embodiment of the present invention.
FIG. 12 is a side sectional view showing the configuration of the collimator according to the second embodiment of the present invention. The collimator 60 according to the present embodiment has the configuration shown in FIG.
A polarizing glass 61 was provided behind the collimating lens 52 instead of the polarizing glass 53 in the zero collimator 50. Other configurations are almost the same as those in FIG.
The same numbers are assigned and the description is omitted. However, spacer 5
4 has a shape excluding the protruding piece 54c.

Further, a spacer 62 is provided between the collimating lens 52 and the polarizing glass 61. Like the polarizing glass 53, the polarizing glass 61 is subjected to a process including a stretching process on a glass material mixed with raw material fine particles containing a metal element to have a predetermined aspect ratio, and the longitudinal direction thereof is arranged in one direction. Needle-like metal fine particles are formed inside to impart polarization characteristics.

As described above, in this embodiment, the polarizing glass 6
Since 1 is provided behind the collimating lens 52, parallel light can be incident on the polarizing glass 61 and polarized there. Therefore, higher-performance polarized light can be output.

According to the experiment of the present inventor, the wavelength 1550
When an optical fiber 56 (panda fiber), a polarizing glass 53, and a collimating lens 52 for nm are used, the insertion loss is 1 dB or less, the crosstalk is 50 dB or more, the return loss is 20 dB or more, and the emission beam shape is 0.6 mm or less. Polarized light and parallel light could be obtained.

In this embodiment, an example in which a panda fiber is used as the optical fiber 56 has been described. However, the present invention is not limited to this, and other polarization maintaining fibers such as an elliptical core fiber and an elliptical jacket fiber may be used. Good.

Further, in this embodiment, an example is shown in which the optical fiber 56 is a polarization maintaining fiber. However, the present invention is not limited to this, and two independent modes polarized in two directions perpendicular to each other in the fiber cross section are propagated. To a single mode optical fiber.

When both the end face 55c of the capillary 55 and the end face 56a of the optical fiber 56 are polished so as to be inclined about 8 ° in the axial direction from the state shown in FIG. 10, the return loss can be increased to 40 dB or more. .

Furthermore, if a wavelength plate that can be manually adjusted is provided behind the polarizing glass 61, the polarization direction of the light emitted from the polarizing glass 61 can be changed to an arbitrary state.

[0076]

As described above, according to the present invention, the direction of the polarization axis of the light propagating through the optical fiber can be confirmed by the reference surface formed on the holding member attached to the end of the optical fiber. Therefore, the polarization axis of the light propagating through the optical component and the polarization axis of the light propagating through the optical fiber can always have a predetermined angle relationship.

Further, in the present invention, since the optical component has a collimating lens for converting the light emitted from the optical fiber into a collimated light and a polarizing glass for polarizing the light, the effective diameter is increased. And can be installed at a position distant from the emission end face of the optical fiber. Therefore, the polarization axis alignment and assembly are facilitated. Further, since the return loss and the crosstalk can be increased, a high-performance optical device can be obtained.

Further, since the optical fiber and the polarizing glass are connected at a predetermined distance from each other, reflected return light can be suppressed. Further, by using the polarizing glass having small incident angle dependence, the end face of the optical fiber can be inclined, and the reflected return light can be further reduced. Further, since the optical fiber and the polarizing glass are connected so that their polarization axes coincide, it is possible to prevent a reduction in crosstalk.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams showing a configuration of a capillary according to a first reference example of the present invention, wherein FIG. 1A is a perspective view and FIG. 1B is a perspective view showing a state where an optical fiber is inserted.

FIG. 2 is a plan view showing a schematic configuration of an optical waveguide component according to a first reference example of the present invention.

FIG. 3 is a cross-sectional view of the optical waveguide component of FIG. 2 along a longitudinal direction.

FIG. 4 is a diagram showing a procedure for connecting an optical fiber and a capillary to an optical waveguide component.

FIG. 5 is an enlarged view of an end face of the optical fiber.

FIG. 6 is a plan view showing a schematic configuration of an optical waveguide component according to a second reference example of the present invention.

7A and 7B are diagrams showing a configuration of a capillary according to a second reference example of the present invention, wherein FIG. 7A is a perspective view, and FIG. 7B is a perspective view showing a state where an optical fiber is inserted.

FIG. 8 is a side sectional view showing a configuration of a collimator according to a third reference example of the present invention.

FIG. 9 is a side sectional view showing a configuration of a collimator according to a fourth reference example of the present invention.

FIG. 10 is a side sectional view showing the configuration of the collimator according to the first embodiment of the present invention.

FIG. 11 is a diagram showing a configuration and a coupling relationship of a polarizing glass, a spacer, and a capillary in FIG. 10;

FIG. 12 is a side sectional view showing a configuration of a collimator according to a second embodiment of the present invention.

FIG. 13 is a plan view showing an example of an optical waveguide component in which optical fibers are coupled by a conventional method.

14 is a diagram showing a method of connecting an optical fiber to the optical waveguide surface of FIG.

FIG. 15 is an enlarged view of an end face of the optical fiber of FIG.

FIG. 16 is a diagram showing a schematic configuration of a conventional collimator.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 optical waveguide component 10 d lower surface (first reference surface) 11 optical waveguide surface 12, 13 optical fiber 14, 15 capillary 15 b cutout surface (second reference surface) 50 collimator 52 collimating lens 53 polarizing glass 54 spacer 55 capillary 56 Optical fiber 61 Polarized glass

Continuation of the front page (56) References JP-A-4-3484 (JP, A) JP-A-6-242346 (JP, A) JP-A-61-80113 (JP, A) JP-A-61-185705 (JP) JP-A-6-27419 (JP, A) JP-A-1-173005 (JP, A) JP-A-61-106 (JP, U) JP-A-3-29810 (JP, U) Field surveyed (Int.Cl. ⁷ , DB name) G02B 6/16 G02B 6/24 G02B 6/34 G02B 6/36 G02B 27/30

Claims (5)

(57) [Claims] 1. An optical device using an optical fiber, comprising: an optical fiber; a polarizing glass for polarizing light from the optical fiber; and a collimating lens for converting light from the polarizing glass to collimated light. A holding member attached to an end of the optical fiber and having a reference surface indicating a direction of a polarization axis of light propagating through the optical fiber, wherein the reference surface of the holding member fits With parts
Having a spacer to which the polarizing glass is bonded,
By fitting the reference surface and the shape portion, the light
The fiber and the polarizing glass are separated by a predetermined distance, and the optical fiber
The polarization axis of light propagating through the glass and the polarization axis of the polarizing glass are
An optical device characterized by being matched . 2. An optical device using an optical fiber, comprising: an optical fiber; a collimating lens for converting light from the optical fiber into collimated light; and a polarizing glass for polarizing light from the collimating lens. A holding member attached to an end of the optical fiber and having a reference surface indicating a direction of a polarization axis of light propagating through the optical fiber, a predetermined distance between the optical fiber and the collimating lens; is connected Contact <br/> have been a polarizing glass and the optical fiber,
A space that is connected so that its polarization axes coincide and has a shape portion into which the reference surface of the holding member fits.
The reference surface and the shape portion are fitted.
Thus, the optical fiber and the polarizing glass are kept at a predetermined distance.
The polarization axis of the light propagating through the optical fiber and the polarization axis.
An optical device characterized in that the polarization axes of the laths are matched . 3. A shape portion to which a reference surface of the holding member fits.
And the end face of the optical fiber and the collimation
Scan to fix the distance between Torenzu a predetermined distance pacer, the
The optical device according to claim 1, further comprising:
Place. 4. The method according to claim 1, wherein the predetermined distance is equal to the focus of the collimator lens.
4. The optical device according to claim 3, wherein the distance is a point distance.
Place. 5. The optical fiber according to claim 1, wherein an end face of the optical fiber is inclined with respect to an optical axis.
Claims characterized by being formed so as to be inclined
5. The optical device according to 1, 2, 3, or 4.