WO2018003940A1

WO2018003940A1 - Optical receptacle and optical transceiver

Info

Publication number: WO2018003940A1
Application number: PCT/JP2017/024011
Authority: WO
Inventors: 祥近藤; 弘嗣我妻; 哲史兼行; 悟史箱崎; 裕希佐藤; 康平冨永
Original assignee: Toto株式会社
Priority date: 2016-06-29
Filing date: 2017-06-29
Publication date: 2018-01-04

Abstract

An optical receptacle is provided with: a fiber stub that includes an optical fiber having a core and cladding, a ferrule having a through hole, and an elastic member for affixing the optical fiber; retention hardware for retaining the fiber stub; and a sleeve for retaining a plug ferrule. The optical fiber has one end surface and another end surface on the opposite side. The optical fiber has a first part on the other end surface side, a third part on the one end surface side, and a second part between these. The core diameter of the first part is smaller than the core diameter of the third part. The core diameter of the second part becomes larger moving from the first to the third part. The elastic member is provided between the optical fiber and the inside wall of the through hole. Thus, it is possible to provide an optical receptacle and optical transceiver wherein the total length of the optical module is reduced, highly precise dimensional tolerance is unnecessary for the length in the axial direction of fiber, reductions in coupling efficiency are prevented, and MFD conversion loss is suppressed.

Description

Optical receptacle and optical transceiver

An aspect of the present invention generally relates to an optical transceiver and module for optical communication, and more particularly to an optical receptacle suitable for a module for high-speed communication.

An optical receptacle is used as a component for optically connecting an optical fiber connector to an optical element such as a light receiving element or a light emitting element in an optical module of an optical communication transceiver.

In recent years, with the increase in IP traffic, optical communication transceivers are required to increase in speed. In general, the shape of a transceiver or the like that adopts a receptacle-type optical module is standardized, and if the modulation speed of an optical signal emitted from a semiconductor laser, which is one of optical elements, is increased, the space required for an electric circuit increases. Therefore, downsizing of the optical module is demanded.

The mode field diameter of a semiconductor laser element is generally smaller than the core diameter of 10 μm of an optical fiber used as an optical signal transmission path.

In recent years, in order to further increase the communication speed of optical transceivers, a single module has a plurality of semiconductor lasers, and light emitted from each semiconductor laser is transmitted into an optical waveguide formed inside a plate-shaped member. Then, an optical module having a structure that is optically coupled to an optical fiber of an optical receptacle after being combined into one waveguide is also used. In these optical modules, in order to reduce the size, it is necessary to reduce the size of the plate member having the optical waveguide described above, and the core diameter of the optical waveguide tends to be reduced.

Even in an optical module that uses a light receiving element instead of a light emitting element, there is a tendency to reduce the light receiving diameter of the light receiving element in order to use it for higher speed and longer distance communication.

A lens for condensing light emitted from a semiconductor laser element onto a fiber core or condensing light emitted from a fiber core onto a light receiving element has a difference between the mode field diameter of the optical element and the fiber core diameter. In some cases, it is necessary to have a magnification function. However, the larger the difference, the longer the focal length of the lens, or the larger the number of necessary lenses, and there is a problem that the optical system becomes complicated and expensive.

In order to prevent an increase in the overall length of the module or complication of the optical system, the magnification by the lens is kept small. Instead, a lens is formed on a part of the optical fiber side end face of the optical fiber, or a GI fiber is fused. Thus, a method is known in which the mode field diameter of the incident light is enlarged and the optimum mode field diameter for the fiber is incident on the fiber end face (for example, Patent Document 1).

However, since the method of Patent Document 1 uses a GI fiber whose mode field diameter periodically changes, in order to obtain an optimum mode field diameter, the length of the GI fiber must be strictly controlled. There was a problem that it was difficult to manage.

In addition, when a fiber having different refractive indexes is fused stepwise from the core center to the outer peripheral portion in the radial direction, such as a GI fiber, a core having a different refractive index is fused in a fusion technique in which the fiber end faces are fused and integrated. Since it melts and mixes, it is difficult to manage the refractive index around the fused part, and there is a problem that optical loss increases.

Patent Document 2 proposes an optical receptacle in which the optical element side of the optical fiber is formed in a tapered shape, and the mode field diameter on the optical element side is smaller than the mode field diameter on the PC (Physical Contact) side. Thereby, connection loss can be suppressed. However, in the configuration of Patent Document 2, the taper shape is located at the end on the optical element side. Both end portions of the optical fiber need to be mirrored (polished) so as not to cause adverse effects of light entering and exiting. For this reason, there has been a problem that the diameter varies depending on the degree of mirror finishing, and it is difficult to stably control the mode field diameter. That is, the configuration of Patent Document 2 also requires a highly accurate dimensional tolerance with respect to the axial length of the optical fiber.

JP 2006-154243 A JP 2006-119633 A

An aspect of the present invention has been made to solve the above-described problems. The core of the optical element side end surface of the optical fiber is made smaller, and the refractive index difference between the core and the clad than the fiber generally used in the transmission line is reduced. While fusing a large fiber, it contributes to shortening the total length of the optical module, while the refractive index and the fiber are generally used in the transmission line, and the refractive index and the fusion part of the fiber having a large refractive index difference between the core and the clad. To provide an optical receptacle and an optical transceiver capable of suppressing mode field conversion efficiency by forming a portion where the core diameter gradually changes, and consequently suppressing a decrease in coupling efficiency from an optical element to a plug ferrule. With the goal.

The first invention includes an optical fiber having a core and a cladding for conducting light, a ferrule having a through hole to which the optical fiber is fixed, and a first elastic member for fixing the optical fiber to the through hole. A fiber stub, a holding tool for holding the fiber stub, and a sleeve for holding the fiber stub at one end and holding the plug ferrule at the other end, the fiber stub having a plug ferrule of the ferrule, One end face on the side to be optically connected and the other end face opposite to the one end face, and the optical fiber includes a first part on the other end face side and a third part on the one end face side. , Having a second part between the first part and the third part, wherein the core diameter in the first part is smaller than the core diameter in the third part, and the second part In The core diameter increases from the first part side toward the third part side, the first elastic member is provided between the optical fiber and the inner wall of the through hole, and the holder is The optical receptacle is characterized in that the other end surface side of the fiber stub is held, and the sleeve holds the one end surface side of the fiber stub.

According to this optical receptacle, the core diameter at the end surface of the ferrule opposite to the side optically connected to the plug ferrule is smaller than the core diameter at the end surface of the ferrule on the side optically connected to the plug ferrule. The length of can be reduced.
In addition, since the second portion is formed, a rapid change in the core shape can be suppressed when the first portion transitions to the third portion. Loss can be suppressed.
Furthermore, since the first part and the third part do not change in shape with respect to the axial direction and the loss of light is small, there is no problem regardless of where the second part is located in the inner diameter part of the optical ferrule. As a result, the receptacle can be manufactured economically without requiring precise length control of the fiber.
The optical receptacle is connected to an optical fiber that is generally laid. Generally, the MFD of the optical fiber to be laid is about 10 μm, and the connection loss due to the MFD difference between the plug and the optical receptacle can be suppressed by arranging the third portion on the optical connection side.

According to a second invention, in the first invention, the refractive index of the core of the first portion, the refractive index of the core of the second portion, and the refractive index of the core of the third portion are equal to each other, The refractive index of the cladding of the first part is smaller than the refractive index of the cladding of the third part, and the refractive index of the cladding of the second part is from the first part side to the third part side. It is an optical receptacle characterized by becoming larger.

According to this optical receptacle, by using a fiber having a large refractive index difference, light can be confined without scattering even with a small core diameter, and loss when light enters the fiber can be suppressed. In addition, since the second portion is formed, it is possible to suppress a sudden change in the refractive index difference when the first portion transitions to the third portion. Loss can be suppressed. Moreover, since the core material can be shared and there is no refractive index difference between the cores in the connecting portions of the first part, the second part, and the third part, the loss due to the reflection of the connecting part is suppressed. be able to.

According to a third invention, in the first invention, the refractive index of the cladding of the first portion, the refractive index of the cladding of the second portion, and the refractive index of the cladding of the third portion are equal to each other, The refractive index of the core of the first part is larger than the refractive index of the core of the third part, and the refractive index of the core of the second part is from the first part side to the third part side. It is an optical receptacle characterized by becoming smaller toward.

According to this optical receptacle, since the clad can be formed of the same material, the clad can have uniform physical properties. Thereby, since the melting point becomes uniform, the outer diameter of the clad at the time of fusion can be easily formed.

According to a fourth invention, in any one of the first to third inventions, the core diameter of the second part increases linearly from the first part side toward the third part side. Is an optical receptacle.

According to this optical receptacle, even if the laser that has entered the second portion spreads radially, it enters the boundary between the cladding and the core at a small angle, and the total reflection of the light causes the cladding side Can prevent light from escaping.

According to a fifth invention, in any one of the first to third inventions, the core diameter of the second part increases nonlinearly from the first part side toward the third part side. It is the optical receptacle characterized.

According to this optical receptacle, since it is not necessary to precisely control the fusion fiber pulling speed, the fusion discharge time, and the power when forming the second portion, it can be manufactured relatively easily. it can.

According to a sixth aspect of the present invention, in any one of the first to third aspects, the core of the second portion has a core diameter of the second portion from the first portion side to the third portion side. An optical receptacle characterized by having a step in a part of a region where is increased.

According to this optical receptacle, since it is not necessary to precisely control the fusion fiber pulling speed, the fusion discharge time, and the power when forming the second portion, it can be manufactured relatively easily. it can. In addition, if this shape is adopted, even fibers having different melting points can be connected, so that the options of fibers used for fusion can be expanded.

A seventh invention is an optical receptacle according to any one of the first to sixth inventions, wherein a core diameter in the first portion is 0.5 μm or more and 8 μm or less.

According to this optical receptacle, since the MFD is reduced on the fiber side with respect to the light emitted from the fine optical waveguide, it is not necessary to zoom the light when entering the fiber. Accordingly, the coupling distance can be shortened and the lens can be simplified.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the difference between the refractive index of the core and the refractive index of the cladding in the first portion is the difference between the refractive index of the core and the cladding in the third portion. It is an optical receptacle characterized by being larger than the difference from the refractive index.

According to this optical receptacle, in the first portion, when transmitting light having a beam waist smaller than that in the third portion, the light can be propagated in a single mode and with little loss.

According to a ninth invention, in any one of the first to eighth inventions, the difference between the refractive index of the core and the refractive index of the cladding in the first portion is the difference between the refractive index of the core and the cladding in the second portion. It is an optical receptacle characterized by being larger than the difference from the refractive index.

According to this optical receptacle, when transmitting light having a beam waist smaller than that of the second portion in the first portion, the light can be propagated in a single mode and with little loss.

A tenth aspect of the invention is an optical receptacle according to any one of the first to ninth aspects, wherein a core diameter in the third portion is 8 μm or more and 20 μm or less.

According to this optical receptacle, the single mode fiber for optical communication that is currently used generally and the MFD can be aligned, so that the coupling loss caused by the MFD difference when coupled with the plug ferrule can be suppressed.

In an eleventh aspect of the invention, in any one of the first to tenth aspects, the difference between the refractive index of the core and the refractive index of the cladding in the third portion is the difference between the refractive index of the core and the cladding in the second portion. It is an optical receptacle characterized by being smaller than the difference from the refractive index.

According to this optical receptacle, in the third portion, when transmitting light having a larger beam waist than that of the second portion, light can be propagated in a single mode and with little loss.

According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the difference between the refractive index of the core and the refractive index of the cladding in the second portion is from the first portion side to the third portion side. It is an optical receptacle characterized by becoming smaller toward.

According to this optical receptacle, the refractive index gradually decreases from the first part side toward the third part side, thereby preventing a sudden change in the refractive index between the first part and the third part. And light loss due to reflection or scattering at the coupling position of the first part and the third part can be suppressed.

A thirteenth invention is characterized in that, in any one of the first to twelfth inventions, an outer diameter of the optical fiber in the first portion is equal to an outer diameter of the optical fiber in the third portion. Is an optical receptacle.

According to this optical receptacle, since the outer shapes of the first part and the third part are equal, the center axis deviation between the first part and the third part can be prevented, and the fusion caused by the axis deviation can be prevented. Loss can be suppressed.

A fourteenth invention is characterized in that, in any one of the first to thirteenth inventions, an outer diameter of the optical fiber in the second portion is smaller than an outer diameter of the optical fiber in the first portion. Is an optical receptacle.

According to this optical receptacle, since the first elastic member exists in a wedge shape on the outer periphery of the second portion where the outer diameter of the optical fiber is thin, the optical fiber is prevented from protruding outward from the ferrule, and the optical fiber It is possible to suppress cracks and cracks on the outer periphery.

A fifteenth invention is characterized in that, in any one of the first to fourteenth inventions, an outer diameter of the optical fiber in the second portion is smaller than an outer diameter of the optical fiber in the third portion. Is an optical receptacle.

According to this optical receptacle, the wedge action by the first elastic member provided on the outer side of the clad of the second part is more effective by providing a difference in the clad outer diameter of the second part and the third part. You can do it.

According to a sixteenth aspect of the present invention, in any one of the first to fifteenth aspects, the central portion in the axial direction of the second portion is disposed so as not to overlap an area where the ferrule and the holder are in contact with each other. It is an optical receptacle characterized by being.

According to this optical receptacle, for example, even when the second portion is formed by fusion, stress is applied to the second portion having a relatively lower strength than the first portion and the third portion, and the second portion It is possible to suppress the occurrence of fiber breakage or the like in this portion. The reliability of the optical receptacle can be further improved.

In a seventeenth aspect based on any one of the first to sixteenth aspects, the first portion, the second portion, and the third portion are disposed in the through hole over the entire area. It is an optical receptacle characterized by the above.

According to this optical receptacle, since the entire optical fiber is present in the through-hole of the ferrule, it is possible to suppress problems such as bending and cracking of the optical fiber due to external force.

An eighteenth invention according to any one of the first to seventeenth inventions, further comprising a translucent member fixed to the ferrule, wherein the through hole is provided on the small diameter portion and the other end surface side. A large-diameter portion having a larger diameter than the small-diameter portion, and the entire optical fiber is disposed in the small-diameter portion, and at least a part of the translucent member is disposed in the large-diameter portion. The first elastic member is an optical receptacle provided between the optical fiber and the translucent member.

According to this optical receptacle, by providing the third portion, when light is incident on the fiber from an optical member such as a fine waveguide, the optical connection distance is extended by beam diameter conversion represented by a zoom lens or the like. By providing a large-diameter portion on the ferrule, the incident surface can be further disposed inside the receptacle, and the optical connection distance from the plug connection surface of the optical receptacle to the waveguide can be shortened. it can.

In a nineteenth aspect based on any one of the first to sixteenth aspects, the first portion has a portion protruding from the ferrule, and the second portion and the third portion are disposed over the entire area. An optical receptacle characterized by being disposed in the through hole.

According to this optical receptacle, alignment of the optical element and the optical receptacle can be facilitated by making the optical fiber protrude from the ferrule end face.

According to a twentieth aspect, in the nineteenth aspect, the through hole of the ferrule has a first region in which a width in an orthogonal direction orthogonal to an axial direction corresponds to a width in the orthogonal direction of the optical fiber, A second region that is disposed closer to the other end surface than the first region and widens in the orthogonal direction toward the other end surface, and the axially central portion of the second portion is the first region An optical receptacle characterized by being disposed so as to overlap with a region.

According to this optical receptacle, it is possible to suppress external stress from being applied to the second portion by disposing the central portion in the axial direction of the second portion so as to overlap the first region. Thereby, it is possible to suppress occurrence of fiber breakage or the like in the second portion.

In a twenty-first aspect, in the nineteenth aspect, the through hole of the ferrule has a first region in which a width in an orthogonal direction orthogonal to an axial direction corresponds to a width in the orthogonal direction of the optical fiber, A second region that is disposed closer to the other end surface than the first region and widens in the orthogonal direction toward the other end surface, and the second portion overlaps the first region. An optical receptacle characterized by being arranged.

According to this optical receptacle, it is possible to suppress external stress from being applied to the second portion by disposing the second portion so as to overlap the first region. Thereby, it is possible to suppress occurrence of fiber breakage or the like in the second portion.

In a twenty-second aspect of the invention, in any one of the nineteenth to twenty-first aspects, the apparatus further includes a fixing member that is provided on an end surface side of the portion protruding from the ferrule of the first portion and fixes the optical fiber, The fixing member is an optical receptacle characterized in that the fixing member is spaced apart from the ferrule.

According to this optical receptacle, by providing the fixing member, the position of the optical fiber can be managed with high accuracy even when a part of the optical fiber protrudes from the ferrule. For example, the alignment with the optical element can be accurately performed in a short time.

According to a twenty-third aspect, in the twentieth or twenty-first aspect, the holder holds a portion of the outer surface of the ferrule that is closer to the other end surface than the first region. It is.

According to this optical receptacle, it is possible to further suppress the external stress accompanying the press-fitting into the ferrule holder from being applied to the second portion.

The twenty-fourth invention is an optical receptacle according to any one of the nineteenth to twenty-third inventions, wherein the holder does not protrude from the other end surface.

According to this optical receptacle, the holder can be made into a simple shape, and the member cost of the holder can be suppressed. Moreover, when an optical fiber is bent, it can also suppress that an optical fiber contacts a holder.

A twenty-fifth aspect of the invention is an optical receptacle according to the twentieth or twenty-first aspect of the invention, wherein the holder holds only a portion of the outer surface of the ferrule facing the first region.

According to this optical receptacle, the member cost of the holder can be suppressed, and the optical fiber can be prevented from coming into contact with the holder. Furthermore, the stress applied to the boundary portion between the first region and the second region can be relaxed.

According to a twenty-sixth aspect of the present invention, in any one of the nineteenth to twenty-fifth aspects, the optical fiber further includes a protective member that covers a portion of the optical fiber that extends outward from the ferrule, and a tube that covers the protective member. The optical receptacle is characterized in that a space is provided between the protective member and the tube.

This optical receptacle can suppress the protective member from coming into direct contact with the holder. In addition, stress concentration also occurs at the interface between the tube and the first elastic member even when bending, but since there is a space between the tube and the protective member, the development of cracks is suppressed. be able to. In addition, since the tube exists independently of the optical fiber, there is no limitation on the selection of the material according to the optical characteristics of the optical fiber, and the protective member can be selected by selecting a material stronger than the protective member. Stronger bending resistance can be achieved.

According to a twenty-seventh aspect of the present invention, in any one of the nineteenth to twenty-sixth aspects, the optical fiber further includes a second elastic member that covers the first elastic member at a portion extending outward of the ferrule. 2. The optical receptacle is characterized in that the hardness of the elastic member is lower than the hardness of the first elastic member.

According to this optical receptacle, the optical fiber and the ferrule can realize optical properties, and at the end of the holder, stress relaxation can be realized when bending acts on the optical fiber. can do.

According to a twenty-eighth aspect of the invention, in any one of the first to twenty-seventh aspects, a part of the end face of the ferrule and the optical fiber on the end face of the fiber stub opposite to the side optically connected to the plug ferrule. The optical receptacle is characterized in that an end surface has a predetermined angle from a plane perpendicular to the central axis of the fiber stub.

According to this optical receptacle, a part of the end face of the ferrule and the end face of the optical fiber are polished so as to have a predetermined angle from a plane perpendicular to the central axis of the fiber stub, thereby being connected to the optical receptacle. Among the light emitted from the light emitting element and entering the optical fiber, the light reflected by the end face of the optical fiber can be prevented from returning to the light emitting element, and the optical element can be operated stably.

The twenty-ninth invention is the optical receptacle according to any one of the first to twenty-eighth inventions, wherein the first portion, the second portion, and the third portion are integrally formed. It is.

According to this optical receptacle, by forming the optical fiber integrally, it is possible to suppress the optical loss by preventing the generation of voids at the boundaries of the first part, the second part, and the third part. Can do.

A thirtieth aspect of the present invention is the optical receptacle according to any one of the first to twenty-ninth aspects, wherein the length of the first portion along the central axis of the fiber stub is 5 μm or more. .

According to this optical receptacle, it is possible to suppress optical loss due to variations in the length of optical fiber and polishing.

A thirty-first invention is the optical receptacle according to any one of the first to thirty-first inventions, wherein the length of the third portion along the central axis of the fiber stub is 5 μm or more. .

In a thirty-second invention, in any one of the first to thirty-first inventions, the optical fiber has the smallest details of the smallest outer diameter in the second portion, and the change in the inner diameter of the through hole is: The thickness of the first elastic member is smaller than the change in the outer diameter of the optical fiber, and the thickness of the first elastic member is the largest in the finest detail, and gradually increases from the first portion toward the finest detail. The length in the axial direction of the optical fiber of the first elastic member provided between the second portion and the inner wall is gradually increased from the portion to the most detailed portion. The axial length of the first elastic member provided between the portion and the inner wall, and the axial length of the first elastic member provided between the third portion and the inner wall. An optical receptor characterized by being shorter than at least one of the lengths It is a cycle.

According to this optical receptacle, the first elastic member provided in the smallest detail with the smallest outer diameter of the optical fiber is present in a wedge shape, and the movement of the optical fiber in the axial direction can be suppressed. For example, it is possible to suppress the optical fiber from protruding outward from the ferrule, and to suppress chipping and cracks on the outer periphery of the optical fiber. It can be suppressed that the optical fiber tip is deeper than the tip of the ferrule and an optical loss when coupled with the plug ferrule is increased.

In a thirty-third aspect of the invention according to any one of the first to thirty-second aspects, the eccentric amount of the center of the core when the other end surface is based on the center of the outer diameter of the ferrule is 7 μm or less. An optical receptacle characterized by being.

According to this optical receptacle, at the time of alignment with an optical element such as a semiconductor laser element, at least a part of the light emitted from the optical element can be obtained simply by installing the optical receptacle and the optical element at the initial position. Can be made incident on the core, and alignment work can be facilitated.

A thirty-fourth invention is the invention according to any one of the first to thirty-third inventions, which is orthogonal to the axial direction of the optical fiber between the cladding of the first portion and the cladding of the third portion. The optical receptacle is characterized in that the amount of displacement in the direction to lie is 4 μm or less.

According to this optical receptacle, it is possible to suppress the occurrence of axial misalignment with the plug ferrule on the one end face side optically connected to the plug ferrule. It is possible to suppress an increase in connection loss due to an axial deviation from the plug ferrule.

A thirty-fifth aspect of the present invention is an optical transceiver comprising any one of the first to thirty-four optical receptacles.

According to this optical transceiver, the core on the optical element side end face of the optical fiber is made small, and a fiber having a refractive index difference between the core and the clad larger than that of a fiber generally used for a transmission path is fused. While contributing to shortening the overall length of the module, a part where the refractive index and core diameter gradually change is formed in the fused part of the fiber generally used in the transmission line and the fiber having a large refractive index difference between the core and the cladding. Thus, the conversion efficiency of the mode field can be suppressed, and as a result, a decrease in coupling efficiency from the optical element to the plug ferrule can be suppressed.

While reducing the overall length of the optical module by reducing the core of the optical element side end face of the optical fiber, it does not require high-accuracy dimensional tolerances regarding the axial length of the fiber, and the axial movement of the fiber can be reduced. An optical receptacle and an optical transceiver capable of preventing a reduction in coupling efficiency by suppressing and suppressing a loss of MFD conversion are provided.

It is a schematic cross section of the optical receptacle which shows 1st embodiment of this invention. It is an expanded sectional view of the fiber stub in 1st embodiment of this invention. It is an expanded sectional view in the state where the 2nd portion in a first embodiment of the present invention has expanded linearly. It is a schematic diagram of the beam propagation in the first embodiment of the present invention. It is an expanded sectional view of the state where the 2nd portion in a first embodiment of the present invention is expanding nonlinearly. It is an expanded sectional view of the state which has a level | step difference in the 2nd part in 1st embodiment of this invention. It is a schematic cross section which illustrates the 2nd part in 1st embodiment of this invention. It is an enlarged front view of the fiber stub in the first embodiment of the present invention. It is an expanded sectional view of the optical fiber in 1st embodiment of this invention. It is a graph showing the relationship between the axial shift in the optical connection surface of a fiber stub and a plug ferrule and connection loss. It is an expanded sectional view of the fiber stub in 2nd embodiment of this invention. It is a schematic diagram which illustrates an example of the analysis regarding the conversion part length of a 2nd part. It is a graph showing the analysis result regarding the conversion part length of a 2nd part. It is the contour figure and graph which represent the light intensity distribution of the analysis result regarding the conversion part length of a 2nd part. FIG. 15A to FIG. 15C are schematic views illustrating analysis regarding the length of the first portion. FIG. 16A and FIG. 16B are schematic cross-sectional views illustrating a part of the optical receptacle according to the third embodiment of the invention. It is a typical sectional view which illustrates a part of optical receptacle concerning a 4th embodiment of the present invention. FIG. 10 is a schematic cross-sectional view illustrating a modification of the optical receptacle according to the fourth embodiment of the invention. FIG. 10 is a schematic cross-sectional view illustrating a part of an optical receptacle according to a fifth embodiment of the invention. FIG. 10 is a schematic cross-sectional view illustrating a part of an optical receptacle according to a sixth embodiment of the invention. It is typical sectional drawing showing the modification of the optical receptacle which concerns on the 6th embodiment of this invention. It is typical sectional drawing showing the modification of the optical receptacle which concerns on the 6th embodiment of this invention. It is typical sectional drawing showing the modification of the optical receptacle which concerns on the 6th embodiment of this invention. It is typical sectional drawing showing the modification of the optical receptacle which concerns on the 6th embodiment of this invention. It is typical sectional drawing showing the modification of the optical receptacle which concerns on the 6th embodiment of this invention. FIG. 26A and FIG. 26B are schematic cross-sectional views illustrating an optical receptacle according to the seventh embodiment of the invention. FIGS. 27A to 27E are explanatory views showing an example of the analysis result of the optical receptacle according to the seventh embodiment of the present invention. It is a typical sectional view which illustrates a modification of an optical receptacle concerning a 7th embodiment of the present invention. FIGS. 29A and 29B are schematic views illustrating an optical transceiver according to the eighth embodiment of the invention.

Hereinafter, embodiments of the present invention will be illustrated with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same component in each drawing, and detailed description is abbreviate | omitted suitably.

(First embodiment)
FIG. 1 is a schematic cross-sectional view of an optical receptacle showing a first embodiment of the present invention.
The optical receptacle 1 includes a fiber stub 4, a holder 5 that holds the fiber stub 4, and a sleeve 6 that holds the tip of the fiber stub 4 at one end and a plug ferrule inserted into the optical receptacle 1 at the other end. And. The fiber stub 4 includes an optical fiber 2, a ferrule 3 having a through hole 3 c that holds the optical fiber 2, and an elastic member 9 (first elastic member). The elastic member 9 is provided between the optical fiber 2 and the inner wall of the through hole 3c. The optical fiber 2 is bonded and fixed to the through hole 3 c of the ferrule 3 using an elastic member 9. Note that the plug ferrule to be inserted into the optical receptacle 1 is not shown.

The holder 5 has a bush 5a and a housing 5b. The bush 5 a is fitted on the outer surface of the ferrule 3 and holds the rear end side of the ferrule 3. The housing 5b fits on the outer surface of the bush 5a and covers the fiber stub 4 and the sleeve 6. The housing 5b covers the fiber stub 4 and the sleeve 6 around the axis, and protects the fiber stub 4 and the sleeve 6 from external force and the like. Thus, the bush 5a holds the fiber stub 4 and the sleeve 6 in a state of being accommodated in the housing 5b. The housing 5b is, for example, cylindrical. The outer diameter of the bush 5 a is larger than the outer diameter of the sleeve 6. The inner diameter of the housing 5b is substantially the same as the outer diameter of the bush 5a. The housing 5b fits only on the outer surface of the bush 5a without fitting on the outer surface of the sleeve 6.

Examples of suitable materials for the ferrule 3 include ceramics and glass. In this embodiment, zirconia ceramics is used. The optical fiber 2 is bonded and fixed at the center of the ferrule 3, and one end (end face 3b: FIG. 1) optically connected to the plug ferrule. And a convex spherical surface. Further, in assembling the optical receptacle 1, the fiber stub 4 is often press-fitted and fixed to the holder 5 (bush 5a).

The material suitable for the sleeve 6 includes resin, metal, ceramics, etc. In this embodiment, a split sleeve made of zirconia ceramics having slits in the full length direction was used. The sleeve 6 holds the tip (end face 3b) polished on the convex spherical surface of the fiber stub 4 at one end, and holds the plug ferrule to be inserted into the optical receptacle at the other end.

The optical fiber 2 has a core 8 extending along the central axis C1 and a clad 7 surrounding the core 8. For example, the refractive index of the core is higher than the refractive index of the cladding. As a material of the optical fiber (the core 8 and the clad 7), for example, quartz glass can be cited. Impurities may be added to the quartz glass.

The fiber stub 4 has one end face (end face 3b) optically connected to the plug ferrule and the other end face (end face 3a) opposite to the one end face. The core 8 is exposed from the clad 7 at the end face 3a and the end face 3b.

For example, an optical element such as a semiconductor laser element is disposed on the end face 3a side. Light emitted from a semiconductor laser element or the like enters the optical receptacle 1 from the end face 3 a side and propagates in the core 8. Alternatively, the light incident on the core 8 from the end surface 3b propagates in the core 8 and is emitted from the end surface 3a side toward the optical element.

An optical element such as an isolator may be provided between the end face 3a and an optical element such as a semiconductor laser element. The isolator has, for example, an element (such as a Faraday element) that rotates a polarization angle or a polarizer, and transmits light only in one direction. Thereby, for example, damage to the laser element due to the return light reflected by the end face 3a, noise, and the like can be suppressed.

Further, the fiber stub 4 may be polished so that the end surface 3b is inclined with respect to a plane orthogonal to the central axis C1. That is, the convex spherical end surface 3b may be an oblique convex spherical surface that is inclined with respect to a plane orthogonal to the central axis C1. Thereby, the optical receptacle 1 is optically connected to an APC (AngledngPhysical Contact) connector at the end face 3b, and reflection and connection loss at the connection point can be suppressed.

FIG. 2 is an enlarged cross-sectional view of the fiber stub in the first embodiment of the present invention.
The optical fiber 2 is a single fiber in which a first portion (first portion 21), a second portion (second portion 22), and a third portion (third portion 23) are fused. The first portion of the optical fiber 2 includes a first partial cladding 7a and a first partial core 8a, the second portion includes a second partial cladding 7b and a second partial core 8b, and the third portion includes a third partial cladding 7c and a third portion. The core 8c comprises a fiber stub 4 polished on the convex spherical surface, a third portion on the end surface 3b side, a second portion in the center, and a first portion on the end surface 3a side optically connected to the optical element opposite to the end surface 3b. Is arranged. The holder 5 (bush 5a) holds the end surface 3a side (first portion 21 side) of the fiber stub 4. The sleeve 6 holds the end surface 3 b side (third portion 23 side) of the fiber stub 4. The first partial cladding 7a, the second partial cladding 7b, and the third partial cladding 7c are included in the cladding 7 described with reference to FIG. The first partial core 8a, the second partial core 8b, and the third partial core 8c are included in the core 8 described with reference to FIG.

The core diameter D1 of the first part is smaller than the core diameter D3 of the third part, and the core diameter D2 of the second part gradually increases as the transition from the first part to the third part (see, for example, FIG. 3). . Further, the fiber outer diameter D4 of the first portion and the fiber outer diameter D6 of the third portion are the same, but the fiber outer diameter D5 of the second portion is smaller than them (see, for example, FIG. 3). The core diameter is the length of the core along the direction orthogonal to the optical axis (center axis C1), that is, the core diameter. The fiber outer diameter is the fiber length (cladding length) along the direction orthogonal to the central axis C1, that is, the fiber diameter.

Examples of the method for forming the second part include a method of stretching the optical fiber fusion part while applying heat higher than the melting point of quartz from the outer periphery of the fusion part when the first part and the third part are fused. . The length of the second portion of the fiber stub 4 in the direction of the central axis C1 needs to be designed in consideration of the length with the least loss and the limit length that can be extended while applying heat. The length is desirably 10 micrometers (μm) or more and 1000 μm.

Thus, the optical fiber 2 has the smallest portion NP having the smallest outer diameter in the second portion 22. The change in the inner diameter of the through hole 3 c is smaller than the change in the outer diameter of the optical fiber 2. The inner diameter of the through hole 3 c is substantially constant from the first portion 21 to the third portion 23. The thickness of the elastic member 9 is largest at the most detailed NP, and gradually increases from the first portion 21 toward the most detailed NP, and gradually increases from the third portion 23 toward the most detailed NP. The length of the elastic member 9 provided between the second portion 22 and the inner wall 3c in the axial direction of the optical fiber 2 is the axis of the elastic member 9 provided between the first portion 21 and the inner wall 3c. This is shorter than at least one of the length in the direction and the length in the axial direction of the elastic member 9 provided between the third portion 23 and the inner wall 3c. In this example, the length of the elastic member 9 of the second portion 22 is shorter than both the length of the elastic member 9 of the first portion 21 and the length of the elastic member 9 of the third portion 23.

FIG. 3, FIG. 4, FIG. 5, FIG. 6 and FIG. 7 show the shape of the second part.

FIG. 3 shows a state in which the core diameter D2 of the second part linearly expands as it changes from the first part to the third part. By adopting this shape, even if the laser that has entered the second portion spreads at a spread angle α, as shown in FIG. 4, the light is incident on the wall at a small angle α ′, and light is incident on the cladding side. Prevent running away. However, in order to create this shape, the speed at which the fiber is pulled and the discharge amount, discharge timing, and discharge position for applying heat to the fiber must be strictly controlled. high.

FIG. 5 shows a state in which the core diameter D2 of the second part increases nonlinearly as it changes from the first part to the third part. By adopting this shape, there is a possibility that the loss in the conversion part (second part) is larger than when the core expands linearly, but since the allowable value for the above control items increases, the discharge amount and discharge Even if it is placed on a manufacturing device whose timing cannot be controlled, there is an advantage that it can be created by relatively simple control.

FIG. 6 shows that while the core diameter D2 of the second part changes from the first part to the third part, the core expands nonlinearly, but a part of the boundary between the clad 7 and the core 8 extends to the fiber center axis C1. On the other hand, a state is shown in which a portion S1 (this is referred to as a step) is substantially vertical. By taking this shape, there is an advantage that it can be created even when it is difficult to transfer heat over the entire second portion during fusion.

The difference between the refractive index of the cladding and the refractive index of the core in each part is the largest in the first part, then the second part is the largest, and the third part is the smallest. Because the second part is formed at the time of fusing the first part and the third part, the refractive index difference is large on the first part side, and the refractive index difference is gradually reduced toward the third part side.

¡When the laser is focused to a certain beam waist diameter D7, it has the characteristic of spreading at a spread angle of α degrees. That is, if one of the divergence angle or the beam diameter is determined, the other is inevitably determined.

As a method for producing a refractive index difference between the core and the clad, a method of adding rare earth such as erbium or germanium to quartz glass is known, and examples of the addition target include the core, the clad, or both. The refractive index can be adjusted by the additive substance and concentration in the quartz glass. In each of the first part, the second part, and the third part, the refractive index of the core and the refractive index of the cladding are about 1.4 or more and 1.6 or less, respectively. Since the NA (aperture) that can be incident is determined by the difference in refractive index between the core and the fiber, the fiber used for the first portion has a refractive index difference so that the spread angle α of the laser incident on the first portion matches the NA. It is necessary to use a fixed fiber.

If the divergence angle is determined, the incident diameter is also determined. Therefore, it is necessary to use a fiber having an MFD (mode field diameter) matched to the incident beam diameter together with the refractive index difference.

The length of the first part and the third part in the direction of the central axis C1 is preferably 100 μm or more in order to secure the distance until the incident light settles in a single mode, and the second part penetrates the ferrule 3. It is desirable to adjust so that it may be arrange | positioned near the center of the hole 3c.

In the fiber stub 4, the optical fiber 2 is fixed to the through hole 3 c of the ferrule 3 using an elastic member (adhesive) 9. Here, examples of the material suitable for the adhesive include resin-based adhesives such as epoxy and silicon. In this example, a high-temperature curing type epoxy-based adhesive was used. In the through hole 3 c of the ferrule 3, a space existing between the optical fiber 2 and the inner wall of the ferrule 3 is filled with the same adhesive without any gap.

In the example shown in FIGS. 1 to 6, the fiber outer diameter D5 of the second portion is smaller than the fiber outer diameter D4 of the first portion and smaller than the fiber outer diameter D6 of the third portion. A gap is generated between the ferrule 3 and the outer periphery of the fiber of the second portion in 3c. The gap is filled with the elastic member 9 as an adhesive without any gap. Thereby, the elastic member 9 filled on the outside of the fiber of the second part becomes a wedge for the fiber, and the fiber stub 4 and the plug ferrule inserted into the optical receptacle 1 come into contact with each other for optical connection, Even if an external force is applied parallel to the axial direction, the fiber stub 4 or the optical fiber 2 is prevented from moving in the axial direction.

The elastic member 9 may contain bubbles that do not affect the function of the optical receptacle 1. More specifically, the elastic member 9 may contain bubbles that can prevent the optical fiber 2 from moving due to contact with the plug ferrule because the fixing strength of the optical fiber 2 is lowered due to poor adhesion. . The elastic member 9 may include bubbles having a length of 30 μm or less in the axial direction of the optical fiber 2 (direction along the interface between the optical fiber 2 and the ferrule 3), for example. The elastic member 9 may include bubbles having a maximum diameter of 30 μm or less, for example. Thereby, even when the elastic member 9 contains air bubbles, it is possible to prevent the function of the optical receptacle 1 from being affected. In the present specification, in the “state in which the elastic member 9 is filled” and the “state in which the elastic member 9 is filled without a gap”, the elastic member 9 includes bubbles having an axial length of 30 μm or less. It also includes the case of being out.

Moreover, since the second part is formed by fusing the first part and the third part, the strength of the second part is lower than the strength of the first part or the third part depending on the forming conditions. There is a case. On the other hand, the second portion can be reinforced by filling the outer periphery of the second portion with the elastic member 9.

However, in the embodiment, as shown in FIG. 7, the fiber outer diameter D5 of the second portion may be substantially the same as the fiber outer diameter D4 of the first portion or the fiber outer diameter D5 of the third portion. Good. By taking this shape, it is possible to relatively easily control the discharge amount and the discharge timing when the optical fiber 2 is formed by fusing.

Also, normally, in the optical receptacle 1, in order to prevent reflection of light at the end face 2 a (see FIG. 2) of the optical fiber 2 when light enters the optical fiber 2 or when light is emitted from the optical fiber 2, In the end surface 3a opposite to the end surface 3b polished to the convex spherical surface of the stub 4, the end surface 2a of the optical fiber 2 is a plane substantially perpendicular to the central axis C1 of the ferrule 3 (same as the central axis of the fiber stub). It is polished to become. Here, “substantially perpendicular” is preferably about 85 to 95 degrees with respect to the central axis C1.

In the first embodiment of the present invention, the end face 2a of the optical fiber 2 is polished to a plane perpendicular to the central axis C1 of the fiber stub 4, and the end face 2a of the optical fiber 2 and the end face 3a of the ferrule 3 are further polished. Exist on the same plane. Here, it is preferable that the distance between the end face 2a of the optical fiber 2 and the end face 3a of the ferrule 3 is about −250 nm to +250 nm.

The center of the core 8 of the optical fiber 2 is within the range of 0.005 millimeters (mm) from the center of the ferrule 3 on the end surface 3a opposite to the end surface 3b polished to the convex spherical surface of the fiber stub 4. Thereby, by controlling the position of the core 8 of the optical fiber 2, the connection loss at the time of assembling the optical module can be reduced, and the optical module can be easily assembled.

The convex spherical surface of the fiber stub 4 is usually formed on a plane perpendicular to the central axis C1 of the ferrule 3, but is formed on a plane having a predetermined angle (for example, 4 to 10 degrees) from the perpendicular surface. May be.

FIG. 8 is an enlarged front view of the fiber stub in the first embodiment of the present invention.
As illustrated in FIG. 8, the core 8 may be eccentric with respect to the ferrule 3 due to, for example, a manufacturing error. At this time, at the other end face (end face 3a) opposite to the one end face (end face 3b) optically connected to the plug ferrule, the deviation of the center CL2 of the core 8 when the center CL1 of the outer diameter of the ferrule 3 is used as a reference. The core amount EA is 7 μm or less. Thereby, alignment work with optical elements, such as a semiconductor laser element, can be made easy.

FIG. 9 is an enlarged cross-sectional view of the optical fiber in the first embodiment of the present invention.
As shown in FIG. 9, when forming the optical fiber 2 by fusing two optical fibers, if at least one core of each optical fiber is eccentric with respect to the cladding, the centers of the cores Are welded together. For this reason, a positional shift may occur between the first partial cladding 7a and the third partial cladding 7c in a direction orthogonal to the axial direction.

In this case, the displacement DA in the direction perpendicular to the axial direction of the optical fiber 2 between the first partial cladding 7a of the first portion 21 and the third partial cladding 7c of the third portion 23 is 4 μm or less. is there.

Thereby, it is possible to suppress the occurrence of axial misalignment with the plug ferrule on one end surface (end surface 3b) side optically connected to the plug ferrule. It is possible to suppress an increase in connection loss due to an axial deviation from the plug ferrule. Further, for example, it is possible to prevent the step between the first partial cladding 7 a and the third partial cladding 7 c from being caught by the ferrule 3 and the optical fiber 2 from entering the ferrule 3. Furthermore, it can be suppressed that stress concentration due to an adhesive or the like occurs in the second portion 22 and causes the optical fiber 2 to break. Thus, by reducing the displacement amount DA, it is possible to suppress breakage of the optical fiber 2 and to improve the assembly yield.

FIG. 10 is a graph showing the relationship between the axial shift and the connection loss in the optical connection surface between the fiber stub and the plug ferrule.
The required quality of the connection loss between the fiber stub 4 and the plug ferrule on the optical connection surface side is often 0.5 dB or less. There are various causes of the loss, but it is considered that the influence of the axial deviation between the fiber stub 4 and the plug ferrule is large.

For example, when the displacement amount DA is 4 μm, in order to insert the optical fiber 2 into the ferrule 3, the through hole 3c of the ferrule 3 must be 4 μm or more. When the diameter of the through-hole 3c is large, the optical fiber 2 is biased and bonded, resulting in misalignment of the optical connection surface, which may increase the connection loss. For example, the connection loss on the optical connection surface exceeds 0.5 dB, and the request cannot be satisfied. Therefore, as described above, the displacement amount DA is 4 μm or less. Thereby, the axial shift with the plug ferrule on the optical connection surface can be suppressed, and the connection loss can be suppressed. It is possible to suppress the connection loss from exceeding 0.8 dB.

(Second embodiment)
FIG. 11 is a schematic cross-sectional view of an optical receptacle showing a second embodiment of the present invention.
The members constituting the optical receptacle 1 are the same as those in the first embodiment, and the end surface 3b (see FIG. 11) polished to the convex spherical surface of the ferrule 3 having the optical fiber 2 and the through hole 3c for holding the optical fiber 2. In the opposite end face 3a (see FIG. 11), a part of the end face 2a of the optical fiber 2 and a part of the end face 3b of the ferrule 3 are at a predetermined angle (for example, 4) from a plane perpendicular to the central axis C1 of the ferrule 3. It is polished so as to be a flat surface having a degree of 10 degrees.

This prevents light reflected from the end face 2a of the optical fiber 2 from returning from the light emitting element connected to the optical receptacle 1 and entering the optical fiber 2 from returning to the light emitting element. It can be operated stably.

Usually, in order to form a surface having a predetermined angle from a surface perpendicular to the central axis C1 of the ferrule 3 in the fiber stub 4, the optical fiber 2 is inserted into the through hole 3c of the ferrule 3 and an adhesive is used. After fixing, the ferrule 3 and the optical fiber 2 are formed by polishing simultaneously.

In the first and second embodiments of the present invention, an elastic member (adhesion) for fixing the optical fiber 2 in the through hole 3c of the ferrule 3 on the outer periphery of the portion 2b where the outer diameter of the second portion is reduced. Agent) 9 is filled. For this reason, even if a force parallel to the central axis C1 of the optical fiber is applied, the elastic member acts as a wedge and can suppress the deviation in the central axis direction of the fiber. The phenomenon of jumping out of the ferrule is less likely to occur.

Next, the study on the core diameter, refractive index, and length of the second portion in the central axis C1 direction performed by the present inventor will be described with reference to the drawings.
12 to 14 are schematic views illustrating examples of analysis conditions and analysis results used in the examination.

First, the core diameter will be described.
FIG. 12 is a schematic cross-sectional view showing the optical fiber used in this study.
When a beam having a beam waist having a diameter w1 is incident on a fiber having an MFD having a diameter w2, assuming that there is no axial deviation, angular deviation, and optical axis deviation in the optical axis vertical direction, the coupling efficiency η is It is known that it is required in

According to this theoretical formula, it can be seen that the efficiency is 1 (100%) when w1 = w2 where the beam waist of the laser and the MFD of the fiber coincide. In addition, it is known that the MFD of a single mode fiber has a diameter that is 0.5 to 4 μm larger than the core diameter of the fiber, although it varies depending on the wavelength when the core diameter is in the range of 0 to 10 μm. From this fact, it is desirable that the core diameter of the fiber is smaller by 0.5 to 4 μm than the incident beam waist.

Explanation of refractive index difference. In order for light to propagate through the single mode fiber, it is desirable that the light spread angle θ1 and the light receiving angle θ2 of the fiber match. It is known that θ1 can be obtained by the following equation.

According to this equation, if the beam waist w1 of the incident laser beam is known, the divergence angle θ1 can be obtained. The light receiving angle θ2 of the fiber is

As can be seen from the above, it is found from the refractive index n _{core of the core} and the refractive index n _{clad of the} cladding.

If the incident beam waist w1 is determined, the divergence angle of the beam is inevitably determined, so the difference in refractive index between the core and the clad of the fiber must be determined to be θ2 = θ1. For example, when quartz glass is used for the core and the clad, the refractive index of the core and the clad changes in the range of about 1.4 to 1.6.

The length of the second part in the direction of the central axis C1 will be described. In order to confirm the effect of this difference in length, optical CAE analysis was performed. In this examination, the core diameter D1 of the first portion is 3 μm, the refractive index of the first partial core 8a is 1.49, the core diameter D3 of the third portion is 8.2 μm, and the refractive index of the third partial core 8c is 1.4677, The total length of the fiber was 1000 μm, the refractive indexes of the clads (7a, 7b, and 7c) in each part were 1.4624 in common, and the beam waist diameter D7 of the incident beam was 3.2 μm. Under this condition, it was calculated how the light intensity changes when the length of the second portion in the central axis C1 direction is changed from 0 μm to 500 μm in increments of 100 μm. The lengths of the first part and the third part were (1000 μm − second part length) ÷ 2.

Fig. 13 shows a graph summarizing the analysis results of this analysis. The horizontal axis indicates the length of the second portion in the direction of the central axis C1, and the vertical axis indicates the logarithm of the light intensity at the fiber exit end when the incident light is 1. According to this analysis result, if the length of the second portion in the direction of the central axis C1 is increased, the loss inside the optical fiber 2 is reduced. As the state of the change, the loss rapidly decreases as the length increases from 0 to 100 μm, and the loss becomes almost flat at 100 μm or more. From this, it is considered that the length of the second portion is desirably 100 μm or more.

FIG. 14 is a contour diagram and a graph showing the light intensity distribution in the fiber in an example of the analysis conditions. The vertical axis of the graph indicates the distance from the incident end of the fiber, and the horizontal axis indicates the light intensity. What should be noted in this graph is that light is not substantially attenuated in the process of propagating through the first part and the third part. The incident light is initially reduced in intensity due to light interference, but is stabilized when it has propagated to some extent from the exit end. After that, the second part is entered while maintaining a constant value. In the second part, loss due to MFD conversion and refractive index change occurs, so that the light intensity decreases, and then enters the third part. In the third part, there is almost no change in intensity, and a constant value is maintained until the emission end.

According to one embodiment of the present invention, the length of the first portion and the third portion in the direction of the central axis C1 does not affect the attenuation, so even if the length changes, the function of the fiber and the loss of the entire fiber are not affected. There is no effect. In other words, the lengths of the first part and the third part can be designed with any length of the designer, and the dimensional tolerance of the design dimension can be made large. This advantage does not require strict dimensional accuracy like GI fiber or fiber with lens, and can greatly contribute to the improvement of mass productivity.

Next, a study on the length of the first portion along the central axis C1 direction and the length of the third portion along the central axis C1 direction will be described.
FIG. 15A to FIG. 15C are schematic views illustrating an example of the optical receptacle of the reference example used for the study on the length of the first portion and an analysis result thereof.

The optical receptacle of the reference example has a fiber stub 49 shown in FIG. The structure of the fiber stub 49 of the reference example is the same as the structure in which the first portion 21 (the first partial cladding 7a and the first partial core 8a) is not provided in the fiber stub 4 according to the embodiment.
That is, the fiber stub 49 includes an optical fiber 29 and a ferrule 39 that holds the optical fiber 29. The fiber stub 49 has an end face 39b connected to the plug ferrule and an end face 39a opposite to the end face 39b. In addition, the optical fiber 29 has a second portion 229 (conversion unit) and a third portion 239. The third portion 239 is aligned with the second portion 229 in the axial direction and is continuous with the second portion 229. The second part 229 forms part of the end face 39a, and the third part 239 forms part of the end face 39b. In the central axis C1 direction, the core diameter of the second portion 229 increases toward the third portion 239. The core diameter of the third portion 239 is substantially constant in the direction of the central axis C1. In FIG. 15A, for convenience, some elements such as an elastic member are omitted.

In general, the end surface 39a is polished in a mirror shape. The end surface 39b is polished into a convex spherical shape. Thereby, the loss of light at the end faces 39a and 39b can be suppressed. In the optical receptacle, it is desirable to polish the end face from the viewpoint of connection between the optical element and the optical receptacle (for example, a V-shaped groove is used) and removal of the adhered adhesive.
The polishing amount of the end face 39a is, for example, not less than 5 μm and not more than 50 μm. Thereby, a mirror-like end surface can be formed.

Here, in the fiber stub 49 shown in FIG. 15A, for example, when the end face 39a is polished by about 5 to 50 μm, the length of the second portion 229 is shortened according to the polishing amount. In other words, the end surface position of the second portion 229 (the position of the portion exposed as part of the end surface 39a of the second portion 229) varies by about 5 to 50 μm according to the polishing amount. That is, the core diameter Da on the end face 39a varies. This causes a loss when using a fiber whose MFD changes periodically, such as a GI fiber.

The inventor of the present application analyzed the relationship between the polishing of the end face 39a and the loss as described above. FIG. 15B and FIG. 15C show examples of analysis results. In this examination, before polishing the end face 39a, the length La along the axial direction of the second portion 229 was 50 μm, the core diameter Da at the end face 39a was 3 μm, and the core diameter Db at the end face 39b was 9 μm. The rate of change along the axial direction of the core diameter in the second portion 229 was constant.

FIG. 15B shows the length La of 20% (polishing amount of 10 μm), 40% (polishing amount of 20 μm), 60% (polishing amount of 30 μm) or 70% (polishing amount of 30 μm) of the fiber stub 49 as described above. It represents the loss (dB) when shortened by 80% (polishing amount 40 μm). FIG. 15C is a graph showing the data of FIG. Here, the loss (dB) is calculated from the intensity of light at the emission end (end surface 39b) when light (diameter DL = 3 μm) enters from the end surface 39a.

The loss is -1.06 dB before the end face 39a is polished. From the graph, it can be seen that the loss increases as the second portion 229 is shortened by polishing. For example, when the conversion portion (second portion 229) is shortened by 50% by polishing, the loss is about −3 dB.

As described above, in the reference example in which the first portion is not provided, the loss increases by polishing the end face. In the reference example, even if the core diameter of the end face before polishing is determined in consideration of the polishing amount in advance, the loss varies depending on the variation in the polishing amount. The amount of polishing needs to be strictly controlled, and mass productivity may be reduced.

On the other hand, in the optical receptacle according to the embodiment, a first portion in which the core diameter and the refractive index do not substantially change along the central axis C1 is provided. Even if the length of the first portion along the central axis C1 varies due to the polishing of the end surface 3a, an increase in optical loss and a variation in variation are small. For example, even if the end face position changes within the length of the first portion, the characteristics of the optical receptacle are not substantially deteriorated.

From the above, it is desirable that the length of the first portion along the central axis C1 is equal to or greater than the polishing amount of the end surface 3a. As described above, in order to make the end surface 3a a mirror surface, the end surface 3a is polished by about 5 μm or more and 50 μm or less. Accordingly, the length of the first portion along the central axis C1 is desirably 5 μm or more, and more desirably 50 μm or more if possible. The upper limit of the length along the central axis C1 of the first part is not particularly limited as long as the second part and the third part can be disposed in the fiber stub 4 (in the through hole of the ferrule 3). Therefore, depending on the overall length of the fiber stub 4, the first portion may be extended to about 7 to 10 mm. Thereby, mass productivity can be improved.

15A to 15C are the same in the reference example having no third part, for example. That is, in this case, the core diameter at the end face connected to the plug ferrule varies depending on the polishing amount. Loss increases due to changes in the core diameter at the end face. On the other hand, in the optical receptacle according to the embodiment, a third portion in which the core diameter and the refractive index do not substantially change along the central axis C1 is provided. Even if the length of the third portion along the central axis C1 varies due to the polishing of the end surface 3b, an increase in optical loss and a variation in variation are small.

Thus, the length of the third portion along the central axis C1 is preferably equal to or greater than the polishing amount of the end surface 3b. For example, in order to make the end surface 3b into a convex spherical shape, the end surface 3b is polished by about 5 μm or more and 20 μm or less. Accordingly, the length of the third portion along the central axis C1 is preferably 5 μm or more, and more preferably 20 μm or more if possible. The upper limit of the length of the third portion along the central axis C1 is not particularly limited as long as the first portion and the second portion can be disposed in the fiber stub 4 (in the through hole of the ferrule 3). Therefore, depending on the overall length of the fiber stub 4, the third portion may be extended to about 7 to 10 mm. Thereby, mass productivity can be improved.

As described above, according to the present embodiment, the core diameter D1 of the end surface 3a opposite to the end surface 3b polished to the convex spherical surface of the fiber stub 4 is smaller than the core diameter D2 of the end surface 3b polished to the convex spherical surface. The length of the optical module can be reduced. Further, it is possible to eliminate the need for highly accurate dimensional management with respect to the axial lengths of the first portion and the third portion.
Since the fiber outer diameter D5 of the second portion is smaller than the cladding through-hole 3c, the elastic member 9 is filled in the gap, thereby preventing the fiber from moving in the central axis direction.

(Third embodiment)
FIG. 16A and FIG. 16B are schematic cross-sectional views illustrating a part of the optical receptacle according to the third embodiment of the invention.
FIGS. 16A and 16B show an enlarged view of the fiber stub 4 and the holder 5 (bush 5a) in the optical receptacle according to the present embodiment.
As shown in FIG. 16A, in this example, the axial central portion C2 of the second portion 22 of the optical fiber 2 overlaps with the region A1 where the ferrule 3 and the holder 5 (bush 5a) are in contact with each other. It is arranged so that it does not become. That is, the central portion C2 in the axial direction of the second portion 22 is provided at a position where the fiber stub 4 is not press-fitted into the holder 5 (bush 5a). The axial direction is, for example, the direction in which the first portion 21, the second portion 22, and the third portion 23 are arranged. In other words, the axial direction is the direction in which the optical fiber 2 extends. More specifically, the axial center portion C2 is the axial center of the second portion 22 where the core diameter D2 gradually changes.

As described above, the second portion 22 is formed, for example, by fusing the first portion 21 and the third portion 23 and stretching the fusion portion while applying heat. In this case, the cladding outer shape changes at the fusion part. The cladding outer diameter of the second portion 22 is smaller than the cladding outer diameter of the first portion 21 and the cladding outer diameter of the third portion 23. For this reason, the strength of the second portion 22 is lower than the strength of the first portion 21 and the third portion 23. Further, in the fused portion, there is a possibility that a defect or a gap is generated in the optical fiber 2. In this case, the strength of the second portion 22 is further reduced.

At this time, as shown in FIG. 16A, the central portion C2 in the axial direction of the second portion 22 is disposed so as not to overlap the region A1 where the ferrule 3 and the holder 5 (bush 5a) are in contact. To do. Thereby, for example, even when the second portion 22 is formed by fusion, a stress is applied to the second portion 22 having relatively lower strength than the first portion 21 and the third portion 23, and the The occurrence of fiber breakage or the like in the second portion 22 can be suppressed. The reliability of the optical receptacle 1 can be further improved.

In FIG. 16A, the axial central portion C2 of the second portion 22 is shifted toward the end face 3b optically connected to the plug ferrule with respect to the region A1. As shown in FIG. 16B, the axial center C2 of the second portion 22 may be shifted to the end face 3a side optically connected to the optical element with respect to the region A1.

In FIG. 16A, a part of the second portion 22 overlaps the area A1. Without being limited to this, as shown in FIG. 16B, the entire second portion 22 may not overlap the region A1. When the entire second portion 22 does not overlap with the region A1, it is possible to further suppress the occurrence of stress on the second portion 22 and the occurrence of fiber breakage. On the other hand, when a part of the second portion 22 overlaps the region A1, the length of the fiber stub 4 in the axial direction can be further shortened.

(Fourth embodiment)
FIG. 17 is a schematic cross-sectional view illustrating a part of an optical receptacle according to the fourth embodiment of the invention.
In FIG. 17, the portion of the fiber stub 4 in the optical receptacle according to the present embodiment is shown enlarged.
As shown in FIG. 17, in this example, the fiber stub 4 further includes a translucent member 70 fixed to the ferrule 3. The through hole 3c of the ferrule 3 has a small diameter part DP1 and a large diameter part DP2. The large diameter portion DP2 is provided closer to the end face 3a than the small diameter portion DP1. The large diameter portion DP2 has a larger diameter than the small diameter portion DP1. In other words, the diameter of the large-diameter portion DP2 is the width in the direction orthogonal to the axial direction. The large diameter portion DP2 is a portion that is provided closer to the end surface 3a than the small diameter portion DP1 in the through hole 3c, and is wider than the small diameter portion DP2. Further, the diameter of the large diameter portion DP2 may be increased toward the end surface 3a, for example.

In this example, the entire optical fiber 2 is disposed in the small diameter portion DP1. The translucent member 70 is disposed in the large diameter portion DP2. For example, the whole translucent member 70 is provided in the large diameter portion DP2. A part of the translucent member 70 may protrude from the ferrule 3. That is, at least a part of the translucent member 70 only needs to be provided in the large diameter portion DP2.

In the cross section orthogonal to the axial direction, the cross sectional shapes of the translucent member 70 and the large diameter portion DP2 are, for example, rectangular. The cross-sectional shapes of the translucent member 70 and the large-diameter portion DP2 may be circular, elliptical, or polygonal.

The elastic member 9 is provided in a gap between the optical fiber 2 and the small diameter portion DP1 of the through hole 3c of the ferrule 3, and the gap between the translucent member 70 and the large diameter portion DP2 and the optical fiber. 2 and the translucent member 70. In other words, the elastic member 9 is filled in a gap between the optical fiber 2 and the small diameter portion DP1 of the through hole 3c of the ferrule 3, and between the translucent member 70 and the large diameter portion DP2. The gap and the gap between the optical fiber 2 and the translucent member 70 are filled. Thereby, the optical fiber 2 and the translucent member 70 are bonded and fixed in the through hole 3 c of the ferrule 3 using the elastic member 9.

The end face 2 a of the optical fiber 2 opposite to the side optically connected to the plug ferrule is in close contact with the elastic member 9. An end surface 70 a on the optical fiber 2 side of the translucent member 70 is in close contact with the elastic member 9. The elastic member 9 and the translucent member 70 have translucency. Thereby, the light irradiated from the optical element enters the optical fiber 2 through the translucent member 70 and the elastic member 9, and the light emitted from the optical fiber 2 passes through the translucent member 70 and the elastic member 9. Through the optical element.

At least a part of the end surface 70 b of the translucent member 70 opposite to the optical fiber 2 has a plane that is substantially perpendicular to the central axis C 1 of the optical receptacle 1. Here, the term “substantially perpendicular” refers to, for example, an angle of about 85 degrees or more and 95 degrees or less with respect to the central axis C1 of the optical receptacle 1.

As a method for forming a flat surface on the end surface 70b of the translucent member 70, there is a method using a polishing film having diamond abrasive grains. Further, the surface roughness of the end surface 70b of the translucent member 70 is desirably an arithmetic average roughness of 0.1 micrometers or less in order to minimize the amount of reflected light.

The elastic member 9 is filled with no gap between the optical fiber 2 and the small diameter portion DP1. Thereby, the bias of the elastic member 9 filled around the optical fiber 2 is reduced, and the thermal expansion coefficient of the elastic member 9 and the thermal expansion coefficient of the optical fiber 2 when the optical receptacle 1 is exposed to a temperature change. It is possible to prevent the optical fiber 2 from being broken or cracked due to the difference between the two. Further, since the amount of variation in the diameter direction in the through-hole 3c of the ferrule 3 on the end face 2a opposite to the optically connected side of the plug ferrule of the optical fiber 2 is reduced, the light emitting element and the light receiving element and the end face of the optical fiber 2 The time for aligning is reduced. Here, the material of the elastic member 9 in the small diameter portion DP1 may be different from the material of the elastic member 9 in the large diameter portion DP2.

It is desirable that each of the elastic member 9 and the translucent member 70 has substantially the same refractive index as the refractive index of the core of the optical fiber 2. The substantially same refractive index here is about 1.4 or more and 1.6 or less. The refractive index of the core of the optical fiber 2 is, for example, about 1.46 or more and 1.47 or less. The refractive index of the elastic member 9 is, for example, about 1.4 or more and 1.5 or less. The refractive index of the translucent member 70 is, for example, about 1.4 or more and 1.6 or less. Thereby, reflection of the light in the interface between the translucent member 70 and the elastic member 9 and the interface between the elastic member 9 and the optical fiber 2 can be reduced, and the coupling efficiency of the optical module can be reduced. improves.

The elastic member 9 has a lower elastic modulus than ceramics used as a material for the ferrule 3 and quartz glass used as a material for the optical fiber 2. For example, an epoxy resin, an acrylic resin, a silicon resin, etc. are illustrated.

In an optical receptacle, in order to reduce reflection, it is common to perform polishing so that the end surface 2a of the optical fiber 2 becomes a mirror-like plane. On the other hand, in the configuration shown in FIG. 17, the reflection of light at the end surface 2a can be reduced even if the end surface 2a of the optical fiber 2 is not similarly polished. Furthermore, the fixing strength of the translucent member 70 can be ensured.

Further, by providing the third portion 23 in the optical fiber 2, when light is incident on the optical fiber 2 from an optical member such as a fine waveguide, the optical connection distance is reduced by beam diameter conversion represented by a zoom lens or the like. By suppressing the extension and providing the ferrule 3 with the large-diameter portion DP2, the incident surface can be further disposed inside the receptacle, and the optical connection distance from the plug connection surface of the optical receptacle 1 to the waveguide can be increased. It can be made shorter. For example, the optical receptacle 1 can be miniaturized.

FIG. 18 is a schematic cross-sectional view illustrating a modification of the optical receptacle according to the fourth embodiment of the invention.
As shown in FIG. 18, this example has a structure in which the translucent member 70 of the optical receptacle described with reference to FIG. 17 is replaced with an isolator 72. In the optical receptacle shown in FIG. 18, the configuration other than the isolator 72 is substantially the same as the optical receptacle described with reference to FIG.

The isolator 72 includes a first polarizer 74, a second polarizer 75, and a Faraday rotator 76. The Faraday rotator 76 is provided between the first polarizer 74 and the second polarizer 75. The Faraday rotator 76 includes a material such as garnet. Thereby, the light emitted from the light emitting element and incident on the optical fiber 2 or the light emitted from the optical fiber 2 and incident on the light receiving element can be transmitted only in one direction.

Thus, the isolator 72 may be used as the translucent member 70. When the isolator 72 is used, for example, it is possible to suppress the reflection of light at the end surface 72b of the isolator 72, or to prevent the reflected light from returning to the light emitting element, and to stably operate the light emitting element. . Further, an AR (anti-reflective) coating may be applied to the end surface 72b of the isolator 72 opposite to the optical fiber 2, for example.

(Fifth embodiment)
FIG. 19 is a schematic cross-sectional view illustrating a part of an optical receptacle according to the fifth embodiment of the invention.
FIG. 19 shows an enlarged view of the fiber stub 4 in the optical receptacle according to the present embodiment. As shown in FIG. 19, the first part (first part 21) includes a part (inner side part 21 a) arranged in the through hole 3 c of the ferrule 3 and a part (projecting part) arranged outside the through hole 3 c. 21b). Further, the optical receptacle according to the present embodiment has an elastic member 19. Except for the above, this embodiment is the same as the first or second embodiment.

The protruding portion 21b protrudes outward from the ferrule 3 (the surface of the ferrule 3 opposite to the end surface 3b). That is, the protrusion 21b is not aligned with the ferrule 3 in the direction orthogonal to the central axis C1. The inner portion 21a is aligned with the ferrule 3 in a direction orthogonal to the central axis C1, and is surrounded by the ferrule 3 when viewed along the central axis C1.

Further, the entire area of the second portion and the entire area of the third portion are respectively disposed in the through holes 3c. That is, the entire area of the second portion and the entire area of the third portion are aligned with the ferrule 3 in a direction orthogonal to the central axis C1, and are surrounded by the ferrule 3 when viewed along the central axis C1.

As already described, a module such as a semiconductor laser element and an optical element are provided on the side opposite to the end face 3b of the optical receptacle. FIG. 19 shows a part 31 of the optical element as an example.

For example, the portion 31 of the optical element has a shape (such as a groove) corresponding to the protruding portion 21b. When assembling the optical element and the optical receptacle, the projecting portion 21b is placed on the part 31 of the optical element and pressed directly against the light emitting end of the optical element. Alternatively, light is made incident on the protruding portion 21 from the light emitting end using an element such as a lens. Thereby, the labor of alignment at the time of an assembly can be reduced. In addition, alignment accuracy can be improved, and optical connection loss can be reduced.

The elastic member 19 is provided at the end of the protruding portion 21b on the third portion side. The elastic member 19 is in contact with the protruding portion 21b and the ferrule 3, for example. Thereby, the elastic member 19 protects the first portion. The length L1 along the direction of the central axis C1 of the elastic member 19 is, for example, about 2 mm. For this reason, the length L2 along the direction of the central axis C1 of the protruding portion 21b is desirably 2 mm or more. Further, from the viewpoint of securing the strength of the first portion and reducing the size of the optical receptacle, the length L2 of the protruding portion 21b is desirably 20 mm or less. However, depending on the intended use of the optical receptacle, the length L2 of the protrusion 21b may be 100 mm or less. In addition, since the 2nd part and the 3rd part are arrange | positioned inside the through-hole 3c, they are protected by the ferrule 3. FIG.

(Sixth embodiment)
FIG. 20 is a schematic cross-sectional view illustrating a part of the optical receptacle according to the sixth embodiment of the invention.
FIG. 20 shows an enlarged view of the fiber stub 4 in the optical receptacle according to the present embodiment.
As shown in FIG. 20, in this example, the through hole 3c of the ferrule 3 has a first region R1 and a second region R2. In the optical receptacle shown in FIG. 20, the configuration other than the through hole 3c is substantially the same as that of the optical receptacle described with reference to FIG.

The first region R1 is a region in which the width in the orthogonal direction orthogonal to the axial direction corresponds to the width of the optical fiber 2 in the orthogonal direction. That is, the first region R1 is a portion having substantially the same diameter as the outer diameter of the optical fiber 2 in the through hole 3c. The diameter of the first region R1 is substantially constant along the axial direction. The first region R1 is continuous with the end surface 3b of the ferrule 3. The ferrule 3 holds the optical fiber 2 in the first region R1.

2nd area | region R2 is arrange | positioned rather than 1st area | region R1 at the end surface 3a side. The second region R2 is continuous with the first region R1. Further, in this example, the second region R 2 is continuous with the end face 3 a of the ferrule 3. The second region R2 is a region where the width in the orthogonal direction widens toward the end face 3a side of the ferrule 3. That is, 2nd area | region R2 is a part which a diameter spreads as it goes to the end surface 3a side in the through-hole 3c.

In the second region R2, for example, the diameter continuously increases toward the end face 3a. For example, the diameter in the second region R2 may be increased stepwise toward the end face 3a. However, by continuously expanding the diameter of the second region R2, for example, when the optical fiber 2 is inserted into the through hole 3c, the tip of the optical fiber 2 is placed in the through hole 3c along the inclination of the second region R2. Can be easily inserted. For example, the manufacturability of the optical receptacle 1 can be improved. For example, the elastic member 19 is filled in the second region R2.

The central portion C2 in the axial direction of the second portion 22 is disposed so as to overlap the first region R1. In this example, the entire second portion 22 is disposed so as to overlap the first region R1. For example, a part of the second portion 22 on the end surface 3a side may overlap the second region R2. In the second portion 22, at least the axial center portion C 2 only needs to overlap the first region R 1.

Thus, the second region R2 is provided in the through hole 3c of the ferrule 3. Thereby, the optical fiber 2 can be easily inserted into the through hole 3c, and the manufacturability of the optical receptacle 1 can be improved. In this case, the central portion C2 in the axial direction of the second portion 22 is disposed so as to overlap the first region R1. Thereby, it is possible to suppress external stress from being applied to the second portion 22, and to suppress occurrence of fiber breakage or the like in the second portion 22. And it can suppress more that external stress is added to the 2nd part 22 by arrange | positioning the whole 2nd part 22 so that it may overlap with 1st area | region R1.

The holder 5 (bush 5a) holds, for example, a portion facing the first region R1 and a portion facing the second region R2 on the outer surface of the ferrule 3. At this time, as described above, the central portion C2 in the axial direction of the second portion 22 is disposed so as not to overlap the region A1 where the ferrule 3 and the holder 5 (bush 5a) are in contact. Thereby, generation | occurrence | production of fiber breakage etc. can be suppressed.

FIG. 21 is a schematic cross-sectional view showing a modification of the optical receptacle according to the sixth embodiment of the present invention.
As shown in FIG. 21, in this example, the holder 5 (bush 5 a) holds only the portion of the outer surface of the ferrule 3 that is closer to the end surface 3 a than the first region R 1. For example, the holder 5 (bush 5a) holds only a portion of the outer surface of the ferrule 3 that faces the second region R2. Thereby, it can suppress more that the external stress accompanying the press injection to the holder 5 (bush 5a) of the ferrule 3 is added to the 2nd part 22. FIG.

In this example, the optical receptacle 1 further includes a protective member 10. The protective member 10 covers a portion of the optical fiber 2 that extends outward from the ferrule 3. The protection member 10 has flexibility and bends in any direction together with the optical fiber 2. For the protective member 10, for example, a resin material such as polyester elastomer or acrylate resin is used. The outer diameter of the protective member 10 is, for example, about 0.2 mm to 1.0 mm.

The tip 10a of the protection member 10 is located in the second region R2 of the through hole 3c. The protective member 10 covers a portion of the optical fiber 2 that is not held by the ferrule 3.

The inner peripheral surface 5n of the bush 5a has a first inner peripheral portion IS1 and a second inner peripheral portion IS2. The first inner peripheral portion IS1 fits on the outer surface of the ferrule 3. The second inner peripheral portion IS2 is located behind (the end surface 3a side) of the first inner peripheral portion IS1, protrudes inward from the first inner peripheral portion IS1, and is part of the optical fiber 2 and part of the protective member 10. Around the axis.

The inner diameter of the first inner peripheral portion IS1 of the bush 5a is substantially the same as the outer diameter of the ferrule 3. On the other hand, the inner diameter of the second inner peripheral portion IS2 of the bush 5a is smaller than the outer diameter of the ferrule 3. Accordingly, the second inner peripheral portion IS2 is located behind the end surface 3a of the ferrule 3.

The inner diameter of the second inner peripheral portion IS2 is set to a value larger than the outer diameter of the protective member 10 and smaller than the outer diameter of the ferrule 3, for example. The inner diameter of the portion of the second inner peripheral portion IS2 is, for example, smaller than the opening diameter on the end surface 3a side of the through hole 3c that expands in the second region R2.

Between the end surface 3a of the ferrule 3 and the second inner peripheral portion IS2, a gap SP is provided in the axial direction. The elastic member 9 is also filled in the gap SP. The distance in the axial direction of the gap SP is, for example, longer than the outer diameter of the optical fiber 2. The distance in the axial direction of the gap SP is, for example, about 0.125 mm to 0.2 mm. In other words, the distance in the axial direction of the gap SP is the distance in the axial direction between the end surface 3a of the ferrule 3 and the second inner peripheral portion IS2. In other words, the outer diameter of the optical fiber 2 is the length in the direction orthogonal to the axial direction of the optical fiber 2. Since the optical performance is not affected, the elastic member 9 excluding the first region R1 may contain bubbles of any size.

The bush 5a has a first rear end face BS1 and a second rear end face BS2. The second rear end face BS2 is recessed more to the front end side (end face 3b side) than the first rear end face BS1 on the outer peripheral side than the first rear end face BS1. The first rear end surface BS1 and the second rear end surface BS2 are, for example, planes orthogonal to the axial direction. As described above, the bush 5a protrudes inward in the vicinity of the rear end of the inner peripheral surface 5n. Thereby, the area of 1st rear end surface BS1 and 2nd rear end surface BS2 can be enlarged.

The bush 5a has a chamfered portion 5c between the first rear end surface BS1 and the second inner peripheral portion IS2 (inner peripheral surface 5n). In other words, the diameter of the opening on the rear end side of the bush 5a increases toward the rear end side. The chamfered portion 5c may be a so-called C surface obtained by linearly grinding a corner portion between the first rear end surface BS1 and the second inner peripheral portion IS2, or a corner portion between the first rear end surface BS1 and the second inner peripheral portion IS2. A so-called R-plane obtained by rounding off may be used.

The elastic member 9 has a protruding portion 9p that protrudes outward of the bush 5a on the rear end side of the bush 5a and covers a corner portion between the rear end of the bush 5a and the outer surface of the protection member 10. The outer surface of the protruding portion 9p is, for example, a concave curved surface that is recessed toward the corner portion side and gently connects the rear end of the bush 5a and the outer surface of the protection member 10.

The outer surface of the ferrule 3 has a first contact portion CP1 that contacts the inner peripheral surface 5n of the bush 5a. The outer surface of the bush 5a has a second contact portion CP2 that contacts the inner peripheral surface of the housing 5b. The intermediate point m2 in the axial direction of the second contact part CP2 is located behind the intermediate point m1 in the axial direction of the first contact part CP1.

In this example, the tip 10a of the protection member 10 is located in the second region R2 of the through hole 3c. Thereby, the length of the part which protruded from the protection member 10 of the optical fiber 2 can be shortened as much as possible. For example, the bending of the optical fiber 2 can be suppressed and the optical fiber 2 can be easily inserted into the through hole 3 c of the ferrule 3. For example, the manufacturability of the optical receptacle 1 can be improved.

In this example, the optical fiber 2 and the protective member 10 further extend outward from the bush 5a (holding tool 5), and are bonded and fixed to the bush 5a by the elastic member 9. Thereby, it can suppress that the part which protruded from the protection member 10 of the optical fiber 2 deform | transforms or inclines by external force. Moreover, it can suppress that the front-end | tip of the optical fiber 2 protrudes from the front-end | tip of the ferrule 3 with the application of external force, or retracts on the contrary.

In this example, the elastic member 9 is also filled in the gap SP between the end face 3a of the ferrule 3 and the second inner peripheral portion IS2. Thereby, the deformation | transformation and position shift of the front-end | tip part of the optical fiber 2 accompanying external force can be suppressed more. Since the optical performance is not affected, the elastic member 9 excluding the first region R1 may contain bubbles of any size.

In this example, the bush 5a has a first rear end face BS1 and a second rear end face BS2. Thereby, for example, by using the first rear end surface BS1 as a receiving surface of the adhesive serving as the elastic member 9, it is possible to suppress the adhesive from flowing into the second rear end surface BS2. When the bush 5a is press-fitted into the housing 5b, the second rear end surface BS2 is used as a positioning surface, and the second rear end surface BS2 is pressed into the housing 5b so that the bush 5a and the housing 5b are pressed. It can suppress that position shift arises.

For example, when the application of the adhesive and the positioning of the bush 5a are performed on the same plane, the adhesive flows into the positioning surface, and the bush 5a may be deeply pressed into the housing 5b by the amount of the hardened adhesive. There is sex. By providing the first rear end face BS1 and the second rear end face BS2, such positional deviation can be suppressed and the positional accuracy between the bush 5a and the housing 5b can be increased.

Also, by providing the gap SP, the distance between the second rear end surface BS2 that is the positioning surface and the end surface 3b of the ferrule 3 that is the PC surface can be determined more accurately. For example, when there is no gap SP and the end surface 3a of the ferrule 3 and the second inner peripheral portion IS2 are in contact, the length from the second rear end surface BS2 to the end surface 3b of the ferrule 3 is The thickness of the bush 5a changes depending on the quality (error, variation, etc.). On the other hand, by providing the gap SP as in this example, the length from the second rear end face BS2 to the end face 3b of the ferrule 3 can be determined more accurately without depending on the quality of the parts. Can do. As a result, the reliability and productivity of the optical receptacle 1 can be improved.

Further, when the gap SP is not provided, the ferrule 3 may be fixed obliquely due to the right angle of the end surface 3a of the ferrule 3 or the second inner peripheral portion IS2, or the ferrule 3 may be missing. There is a concern that the bush 5a may be deformed. In this example, by providing the gap SP, it is possible to suppress the oblique press-fitting of the ferrule 3 and the breakage and deformation of the component regardless of the quality of the component.

The error in the overall length of the ferrule 3 is, for example, about ± 0.05 mm (range 0.1 mm). The error in the thickness dimension of the bush 5a is, for example, about ± 0.05 mm (range 0.1 mm). In this case, the axial distance of the gap SP is preferably about 0.2 mm. Thus, the axial distance of the gap SP is made longer than the outer diameter of the optical fiber 2. The distance in the axial direction of the gap SP is set to about 0.125 mm or more and 0.2 mm or less. Thereby, the reliability and productivity of the optical receptacle 1 can be further improved.

Further, the protective member 10 is bonded longer by making the length of the portion of the first rear end face BS1 longer than the length necessary for holding the bush 5a in the housing 5b (length required for press-fitting). Can be fixed. Thereby, the deformation | transformation and position shift of the front-end | tip part of the optical fiber 2 can be suppressed more.

Further, in this example, by providing the chamfered portion 5c between the rear end surface and the inner peripheral surface of the bush 5a, the optical fiber 2 can be easily inserted into the bush 5a, and the productivity can be improved. Further, when the adhesive is applied to the first rear end surface BS1, the chamfered portion 5c can be used as an adhesive reservoir, and the adhesive is more prevented from flowing into the second rear end surface BS2 (positioning surface). be able to.

Further, in this example, the elastic member 9 has a protruding portion 9p. Thereby, when a load is applied by an external force, it is possible to suppress the optical fiber 2 from being locally bent at a corner portion between the rear end of the bush 5a and the outer surface of the protection member 10. For example, the bending base point of the optical fiber 2 can be moved away from the boundary portion between the first region R1 and the second region R2.

In this example, the housing 5b holds the bush 5a by press-fitting. Thereby, holding force can be improved and the bush 5a can be appropriately held with a simple configuration.

Further, in this example, the intermediate point m2 of the second contact part CP2 of the bush 5a is located behind the intermediate point m1 of the first contact part CP1 of the ferrule 3. Thereby, for example, even when the bush 5a is press-fitted into the housing 5b, the tightening force due to the press-fitting is dispersed over a wide area by the second contact portion CP2, and at the boundary portion between the first region R1 and the second region R2. Further, the concentration of external force on the optical fiber 2 can be further suppressed.

FIG. 22 is a schematic cross-sectional view showing a modification of the optical receptacle according to the sixth embodiment of the present invention.
As shown in FIG. 22, in this example, the bush 5 a holds only the outer surface of the fiber stub 4. The inner diameter of the bush 5a is substantially constant. The rear end of the bush 5a does not protrude rearward from the end surface 3a. At this time, at least a part of the bush 5a holds a portion of the outer surface of the ferrule 3 that faces the second region R2. The fiber stub 4 may be located inside the bush 5a. In this example, the protruding portion 9 p of the elastic member 9 is provided at the corner portion between the end surface 3 a of the ferrule 3 and the outer surface of the protective member 10.

Thus, by making the bush 5a a simple shape, the member cost of the bush 5a can be suppressed. Moreover, when the optical fiber 2 is bent, it can also suppress that the optical fiber 2 contacts the bush 5a.

FIG. 23 is a schematic cross-sectional view showing a modification of the optical receptacle according to the sixth embodiment of the present invention.
As illustrated in FIG. 23, in this example, the bush 5 a holds only a portion of the outer surface of the ferrule 3 that faces the first region R 1. The bush 5a holds a portion in front of the second region R2 of the ferrule 3. Thereby, like the above, the member cost of the bush 5a can be suppressed, and the optical fiber 2 can be prevented from coming into contact with the bush 5a. Furthermore, the stress applied to the boundary portion between the first region R1 and the second region R2 can be relaxed.

FIG. 24 is a schematic cross-sectional view showing a modification of the optical receptacle according to the sixth embodiment of the present invention.
As shown in FIG. 24, in this example, the optical receptacle 1 further includes a tube 12. The tube 12 has a cylindrical shape that covers the outer periphery of the protection member 10. The tube 12 has flexibility. The inner diameter of the tube 12 is slightly larger than the outer diameter of the protective member 10, and a space is provided between the tube 12 and the protective member 10. The tip of the tube 12 is located in the second region R2 of the through hole 3c. The position of the tip of the tube 12 is not limited to this, and may be an arbitrary position.

When the protective member 10 is in direct contact with the holder 5, the protective member 10 may be cracked. Moreover, when the interface between the protective member 10 and the elastic member 9 exists at the rear end of the holder 5, bending stress concentrates on the interface, and the protective member 10 may be cracked. The crack generated in the protective member 10 may propagate into the protective member 10 due to repeated bending and may reach the cladding 7 of the optical fiber 2.

By providing the tube 12 outside the protective member 10, it is possible to suppress the protective member 10 from coming into direct contact with the holder 5. In addition, stress concentration occurs at the interface between the tube 12 and the elastic member 9 even when bending is performed. However, since there is a space between the tube 12 and the protective member 10, cracks may develop. Can be suppressed. Further, since the tube 12 exists independently of the optical fiber 2, there is no restriction on the selection of the material according to the optical characteristics of the optical fiber 2, and a material having a stronger strength than the protective member 10 should be selected. Thus, bending resistance stronger than that of the protective member 10 can be realized.

FIG. 25 is a schematic cross-sectional view showing a modification of the optical receptacle according to the sixth embodiment of the present invention.
As shown in FIG. 25, in this example, the optical receptacle 1 further includes an elastic member 14 (second elastic member) in addition to the elastic member 9 (first elastic member).

The elastic member 14 covers a corner portion between the rear end of the holder 5 (bush 5a) and the outer surface of the protection member 10. When the elastic member 9 has the protruding portion 9p, the elastic member 14 covers the protruding portion 9p. The elastic member 14 covers, for example, the entire outer surface of the protruding portion 9p. In other words, the elastic member 14 covers the boundary portion between the elastic member 9 and the protection member 10.

The hardness of the elastic member 14 is lower than the hardness of the elastic member 9. In other words, the elastic modulus of the elastic member 14 is smaller than the elastic modulus of the elastic member 9. The hardness of the elastic member 9 is higher than the hardness of the protective member 10. The hardness of the elastic member 14 is, for example, about the same as the hardness of the protection member 10. The hardness of the elastic member 14 is, for example, not less than 0.8 times and not more than 1.2 times the hardness of the protective member 10. The hardness of the protective member 10 is, for example, about Shore D20 to 30. In this case, the hardness of the elastic member 14 is about shore D20 to 30 as well.

As described above, a resin material such as polyester elastomer or acrylate resin is used for the protective member 10. As described above, a resin material such as an epoxy resin is used for the elastic member 9. For the elastic member 14, for example, a resin material such as polyester resin, acrylic resin, or silicone resin is used. For example, a resin adhesive is used for the elastic member 9 and the elastic member 14. In this case, the hardness of the elastic member 9 and the hardness of the elastic member 14 are the hardnesses after the adhesive is cured (after complete curing).

The material of the elastic member 9 is preferably a low outgas material having a refractive index optically close to that of glass. In addition, the elastic member 9 is required to have a certain adhesive strength such that the optical fiber 2 moves during optical connection with the plug ferrule. On the other hand, the material of the elastic member 14 is preferably a material having a low elastic modulus in order to relieve stress. In addition, the elastic member 14 may be arrange | positioned over the inner side of the holder 5, without restricting to the end surface of the holder 5 (bush 5a).

As described above, by providing the

elastic members

9 and 14, the optical fiber 2 and the ferrule 3 have optical properties, and at the end of the holder 5, stress relaxation when bending acts on the optical fiber 2. It is possible to realize the two characteristics.

(Seventh embodiment)
FIG. 26A and FIG. 26B are schematic cross-sectional views illustrating an optical receptacle according to the seventh embodiment of the invention.
As shown in FIG. 26A and FIG. 26B, in this example, a fixing member 80 is further provided. In the optical receptacle shown in FIGS. 26A and 26B, the configuration other than the fixing member 80 is substantially the same as the optical receptacle described with reference to FIG.

The fixing member 80 is provided on the end surface 2a side of the portion protruding from the ferrule 3 of the first portion 21, and fixes the optical fiber 2. The fixing member 80 is disposed away from the ferrule 3. In other words, the fixing member 80 is disposed away from the end surface 3 a of the ferrule 3.

The fixing member 80 includes a base portion 81, a lid portion 82, and an elastic member 83. The base part 81 has a substantially rectangular block shape. A groove 81 a is provided on the upper surface of the base portion 81. The groove 81 a is formed according to the shape of the optical fiber 2. The base part 81 accommodates one end of the optical fiber 2 in the groove 81a. Thereby, the base part 81 supports the lower part of the end of the optical fiber 2. The shape of the groove 81a is, for example, a V shape.

The lid portion 82 is provided on the base portion 81 and closes the groove 81 a of the base portion 81. The lid 82 covers the upper part of one end of the optical fiber 2 accommodated in the groove 81a. Thus, the fixing member 80 covers one end of the optical fiber 2 around the axis by the base portion 81 and the lid portion 82. For the base portion 81 and the lid portion 82 of the fixing member 80, for example, optical glass such as quartz glass is used. The material of the base portion 81 and the lid portion 82 may be, for example, a brittle material such as ceramics or a metal material such as stainless steel.

The elastic member 83 is provided between the base portion 81 and the lid portion 82. The elastic member 83 is filled in the groove 81a. The elastic member 83 adheres and fixes the lid portion 82 and one end of the optical fiber 2 to the base portion 81. Thereby, one end of the optical fiber 2 is fixed to the fixing member 80. For the elastic member 83, for example, an epoxy resin, an acrylic resin, a silicon resin, or the like is used.

The optical fiber 2 is provided with a coating 86. The coating 86 covers a portion between the ferrule 3 and the fixing member 80 of the optical fiber 2. In other words, the coating 86 covers a portion of the optical fiber 2 that is not covered with the ferrule 3 and the fixing member 80. Thereby, the coating 86 protects the portion of the optical fiber 2 exposed from the ferrule 3 and the fixing member 80. For the covering 86, for example, a resin material is used.

The end surface 2a of the optical fiber 2 connected to the optical element is substantially flush with the end surface of the base portion 81 and the end surface of the lid portion 82, for example. The end surface 2a of the optical fiber 2 may protrude from the end surface of the base portion 81 and the end surface of the lid portion 82, for example.

When the optical fiber 2 and the optical element are combined to cause light to enter and exit, or when the light is condensed on the end surface 2a of the optical fiber 2 via a lens or the like, the optical fiber 2 having a small core diameter and a laser having a small diameter The light must be accurately aligned. For this reason, for example, the alignment accuracy required compared to the alignment of 10 μm laser light becomes strict.

FIGS. 27A to 27E are explanatory views showing an example of the analysis result of the optical receptacle according to the seventh embodiment of the present invention.
As shown in FIG. 27A, in the analysis, the axial misalignment between the central portion where the light is collected and the central portion of the core (Axial misalignment) and the axial position of the light condensing point ( The optical loss is obtained when the defocus) and the mode field diameter (MFD) of the optical fiber 2 are changed.

FIGS. 27B to 27E are graphs showing examples of analysis results.
As shown in FIGS. 27B to 27E, the loss of light increases as the magnitude of the axis deviation increases. On the other hand, when the defocus amount is increased, it is possible to reduce the loss of light due to the axis deviation. Then, the loss of light due to the axis deviation tends to increase as the mode field diameter of the optical fiber 2 decreases.

Thus, as the core diameter of the optical fiber 2 becomes smaller, higher alignment accuracy with the optical element is required. On the other hand, in the optical receptacle according to the present embodiment, by providing the fixing member 80, even when a part of the optical fiber 2 having a small core diameter is protruded from the ferrule 3, the position of the optical fiber 2 is high. It can be managed with accuracy. For example, the alignment with the optical element can be accurately performed in a short time. For example, the alignment state can be maintained with high accuracy.

On the other end face (end face 3a) opposite to the one end face (end face 3b) optically connected to the plug ferrule, the eccentric amount EA of the center of the core 8 with respect to the center of the outer diameter of the ferrule 3 is 7 μm or less. More preferably, the eccentricity EA is 5.6 μm or less.

The light emitted from an optical element such as a semiconductor laser element enters the core 8 most efficiently when the center of the optical element coincides with the center of the core 8. During alignment, if the light emitted from the optical element is incident on the core 8 at the initial position (the state in which the optical receptacle and the optical element are merely mechanically installed) By monitoring only light fluctuations, the center of the optical element can be easily aligned with the center of the core 8.

When the light radiated from the optical element is 1 mW, when the light incident on the core 8 of the optical receptacle is measured in a state where the optical element is not radiated, for example, the incident light quantity in a state of variation of 1 μW or less is measured. The This is considered to be because light in a measurement environment such as sunlight or illumination light enters. If 1 μW is replaced with a loss with 1 mW as a reference, it becomes −30 dB.

Approximate calculation of −30 dB from the loss result of the positional deviation between the laser and the optical fiber 2 performed in FIG. 27 yields 5.6 μm in FIG. Considering the case where the output of the optical element is high, the eccentricity of the core 8 is managed at 7 μm or less.

Thereby, when performing alignment work with an optical element such as a semiconductor laser element, at least a part of the light emitted from the optical element is transferred to the core 8 only by installing the optical receptacle and the optical element at the initial position. It can be made incident, and alignment work can be facilitated. And by making the eccentricity EA 5.6 μm or less, the alignment work can be made easier. The configuration for setting the eccentricity EA in this way is particularly effective in the configuration in which the core 8 is exposed from the clad 7 at the end face 3a and the end face 3b, as shown in FIGS. is there.

FIG. 28 is a schematic cross-sectional view illustrating a modification of the optical receptacle according to the seventh embodiment of the invention.
As shown in FIG. 28, the end surface 2a of the optical fiber 2 connected to the optical element, the end surface of the base portion 81, and the end surface of the lid portion 82 may be polished obliquely.

(Eighth embodiment)
FIGS. 29A and 29B are schematic views illustrating an optical transceiver according to the eighth embodiment of the invention.
As illustrated in FIG. 29A, the optical transceiver 200 according to the present embodiment includes the optical receptacle 1, the optical element 110, and the control board 120.

A circuit or the like is formed on the control board 120. The control board 120 is electrically connected to the optical element 110. The control board 120 controls the operation of the optical element 110.

The optical element 110 is, for example, a light receiving element or a light emitting element. In this example, the optical element 110 is a light emitting unit. The optical element 110 includes a laser diode 111 and a lens 112. The laser diode 111 is controlled by the control board 120 and emits light to the fiber stub 4 of the optical receptacle 1. The lens 112 is located between the optical receptacle 1 and the laser diode 111 on the optical path of the emitted light.

Note that the optical element 110 may have an element 113 as shown in FIG. The element 113 includes a laser diode and an optical waveguide having a small core diameter. Light propagating through the core of the waveguide enters the optical receptacle 1 through the lens 112. The optical waveguide is formed by, for example, silicon photonics. A quartz waveguide may be used as the optical waveguide. In the embodiment, the light emitted from the laser diode or the optical waveguide may be directly incident on the optical receptacle 1 without providing the lens 112.

Further, a plug ferrule 50 is inserted into the optical receptacle 1. The plug ferrule 50 is held by the sleeve 6. The optical fiber 2 is optically connected to the plug ferrule 50 at the end face 3b. As a result, the optical element 110 and the plug ferrule 50 are optically connected via the optical receptacle, and optical communication is possible.

The embodiment of the present invention has been described above. However, the present invention is not limited to these descriptions. As long as the features of the present invention are provided, those skilled in the art appropriately modified the design of the above-described embodiments are also included in the scope of the present invention. For example, the shape, size, material, arrangement, etc. of each element included in the fiber stub 4 and the like, the installation form of the optical fiber 2 and the ferrule 3 are not limited to those illustrated, and can be changed as appropriate.
Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

1 optical receptacle, 2 optical fiber, 2a optical fiber end face, 3 ferrule, 3a optical end face to be optically connected to optical element, 3b optical end face to be connected to plug ferrule, 3c optical through hole, 4 optical fiber stub, 5 optical holder, 5a Bush, 5b housing, 6 sleeve, 7a first partial cladding, 7b second partial cladding, 7c third partial cladding, 8a first partial core, 8b second partial core, 8c third partial core, 9, 14, 19th elastic member, 21 first part, 21a inner part, 21b protruding part, 22 second part, 23 third part, 29 optical fiber, 31 一部分 optical element part, 39 ferrule, 39a optical element end face that is optically connected, 39b Plug ferrule and optical connection End face, 49 mm fiber stub, 50 mm plug ferrule, 70 mm translucent member, 72 mm isolator, 74 mm first polarizer, 75 mm second polarizer, 76 mm Faraday rotator, 80 mm fixed member, 81 mm base, 82 mm lid , 83 mm elastic member, 86 mm coating, 110 mm optical element, 111 mm laser diode, 112 mm lens, 113 mm element, 120 mm control board, 229 mm second part, 239 mm third part, D1 mm first part core diameter, D2 mm second part core diameter , D3 second part core diameter, D4 first part fiber outer diameter, D5 second part fiber outer diameter, D6 third part fiber outer diameter, D7 beam waist diameter, C1 中心 fiber stub 4 central axis, L1 elastic The length of the member, the length of the L2 protrusion, the S1 portion, Angle alpha divergence angle, alpha 'boundary and the beam of the second portion weaves

Claims

An optical fiber having a core and a cladding for conducting light, a ferrule having a through hole to which the optical fiber is fixed, a first elastic member for fixing the optical fiber to the through hole, and a fiber stub.
A holder for holding the fiber stub;
A sleeve that holds the fiber stub at one end and a plug ferrule at the other end;
With
The fiber stub has one end surface on the side optically connected to the plug ferrule of the ferrule, and the other end surface opposite to the one end surface,
The optical fiber has a first portion on the other end surface side, a third portion on the one end surface side, and a second portion between the first portion and the third portion,
The core diameter in the first part is smaller than the core diameter in the third part,
The core diameter in the second part increases from the first part side toward the third part side,
The first elastic member is provided between the optical fiber and the inner wall of the through hole,
The holder holds the other end surface side of the fiber stub,
The optical receptacle, wherein the sleeve holds the one end face side of the fiber stub.
The refractive index of the core of the first part, the refractive index of the core of the second part, and the refractive index of the core in the third part are equal to each other,
The refractive index of the cladding of the first portion is smaller than the refractive index of the cladding of the third portion,
2. The optical receptacle according to claim 1, wherein a refractive index of the cladding of the second portion increases from the first portion side toward the third portion side.
The refractive index of the cladding of the first portion, the refractive index of the cladding of the second portion, and the refractive index of the cladding in the third portion are equal to each other,
The refractive index of the core of the first part is greater than the refractive index of the core of the third part,
2. The optical receptacle according to claim 1, wherein the refractive index of the core of the second portion decreases from the first portion side toward the third portion side.
The optical receptacle according to any one of claims 1 to 3, wherein a core diameter of the second portion increases linearly from the first portion side toward the third portion side. .
The optical receptacle according to any one of claims 1 to 3, wherein a core diameter of the second part increases nonlinearly from the first part side toward the third part side. .
The core of the second part has a step in a part of a region where the core diameter of the second part is increased from the first part side to the third part side. The optical receptacle according to any one of claims 1 to 3.
The optical receptacle according to any one of claims 1 to 6, wherein a core diameter in the first portion is not less than 0.5 µm and not more than 8 µm.
The difference between the refractive index of the core and the refractive index of the cladding in the first portion is larger than the difference between the refractive index of the core and the refractive index of the cladding in the third portion. The optical receptacle according to any one of the above.
The difference between the refractive index of the core and the refractive index of the cladding in the first portion is larger than the difference between the refractive index of the core and the refractive index of the cladding in the second portion. The optical receptacle according to any one of the above.
10. The optical receptacle according to claim 1, wherein a core diameter in the third portion is 8 μm or more and 20 μm or less.
The difference between the refractive index of the core and the refractive index of the cladding in the third portion is smaller than the difference between the refractive index of the core and the refractive index of the cladding in the second portion. The optical receptacle according to any one of the above.
12. The difference between the refractive index of the core and the refractive index of the cladding in the second portion decreases from the first portion side toward the third portion side. The optical receptacle according to one.
The optical receptacle according to any one of claims 1 to 12, wherein an outer diameter of the optical fiber in the first portion is equal to an outer diameter of the optical fiber in the third portion.
The optical receptacle according to any one of claims 1 to 13, wherein an outer diameter of the optical fiber in the second portion is smaller than an outer diameter of the optical fiber in the first portion.
The optical receptacle according to any one of claims 1 to 14, wherein an outer diameter of the optical fiber in the second portion is smaller than an outer diameter of the optical fiber in the third portion.
The axially central portion of the second portion is disposed so as not to overlap with a region where the ferrule and the holder are in contact with each other. Light receptacle.
The first part, the second part, and the third part are disposed in the through hole over the entire area. Optical receptacle as described.
Further comprising a translucent member fixed to the ferrule,
The through hole has a small diameter portion and a large diameter portion provided on the other end surface side and having a larger diameter than the small diameter portion,
The entire optical fiber is disposed in the small diameter portion,
At least a part of the translucent member is disposed in the large diameter portion,
The optical receptacle according to any one of claims 1 to 17, wherein the first elastic member is provided between the optical fiber and the translucent member.
The first portion has a portion protruding from the ferrule,
The optical receptacle according to any one of claims 1 to 16, wherein the second portion and the third portion are disposed in the through hole over the entire area.
The through hole of the ferrule is disposed on the other end surface side of the first region corresponding to the width in the orthogonal direction of the optical fiber in the orthogonal direction orthogonal to the axial direction, and the first region. And a second region in which the width in the orthogonal direction widens toward the other end surface,
The optical receptacle according to claim 19, wherein an axially central portion of the second portion is disposed so as to overlap the first region.
The through hole of the ferrule is disposed on the other end surface side of the first region corresponding to the width in the orthogonal direction of the optical fiber in the orthogonal direction orthogonal to the axial direction, and the first region. And a second region in which the width in the orthogonal direction widens toward the other end surface,
The optical receptacle according to claim 19, wherein the second portion is disposed so as to overlap the first region.
A fixing member that is provided on an end surface side of the portion protruding from the ferrule of the first portion and fixes the optical fiber;
The optical receptacle according to any one of claims 19 to 21, wherein the fixing member is disposed apart from the ferrule.
The optical receptacle according to claim 20 or 21, wherein the holder holds a portion of the outer surface of the ferrule closer to the other end surface than the first region.
The optical receptacle according to any one of claims 19 to 23, wherein the holder does not protrude from the other end surface.
The optical receptacle according to claim 20 or 21, wherein the holder holds only a portion of the outer surface of the ferrule facing the first region.
A protective member that covers a portion of the optical fiber that extends outward from the ferrule;
A tube covering the protective member;
Further comprising
The optical receptacle according to any one of claims 19 to 25, wherein a space is provided between the protective member and the tube.
A second elastic member that covers the first elastic member in a portion extending outward of the ferrule of the optical fiber;
The optical receptacle according to any one of claims 19 to 26, wherein the hardness of the second elastic member is lower than the hardness of the first elastic member.
A part of the end surface of the ferrule and the end surface of the optical fiber are predetermined from a surface perpendicular to the central axis of the fiber stub on the end surface of the fiber stub opposite to the side optically connected to the plug ferrule. The optical receptacle according to claim 1, wherein the optical receptacle has an angle of
The optical receptacle according to any one of claims 1 to 28, wherein the first part, the second part, and the third part are integrally formed.
The optical receptacle according to any one of claims 1 to 29, wherein the length of the first portion along the central axis of the fiber stub is 5 μm or more.
The optical receptacle according to any one of claims 1 to 30, wherein the length of the third portion along the central axis of the fiber stub is 5 μm or more.
The optical fiber has the smallest details of the smallest outer diameter in the second portion;
The change in the inner diameter of the through hole is smaller than the change in the outer diameter of the optical fiber,
The thickness of the first elastic member is the largest in the finest detail, and gradually increases from the first portion toward the finest detail, and gradually increases from the third portion toward the finest detail. Become
The length of the first elastic member provided between the second part and the inner wall in the axial direction of the optical fiber is the first length provided between the first part and the inner wall. The axial length of the elastic member is shorter than at least one of the axial length of the first elastic member provided between the third portion and the inner wall. Item 32. The optical receptacle according to any one of Items 1 to 31.
The eccentricity of the center of the core with respect to the center of the outer diameter of the ferrule on the other end surface is 7 μm or less, according to any one of claims 1 to 32, Optical receptacle.
The displacement amount in a direction orthogonal to the axial direction of the optical fiber between the clad of the first portion and the clad of the third portion is 4 μm or less. 34. The optical receptacle according to any one of .about.33.
An optical transceiver comprising the optical receptacle according to any one of claims 1 to 34.