Optical connector and method for manufacturing optical connector plug

Abstract

To provide an optical connector capable of connecting an optical fiber with low loss, and a method for manufacturing the optical connector plug.　An optical connector (200) has a waveguide (20) formed using a photocurable resin (13). The waveguide (20) is connected to a core end surface of an optical fiber (10), one end of which is fixedly inserted in an optical connector plug (100), and can transmit an optical signal of a core of the optical fiber (10) to the other end. An end surface of the other end of the waveguide (20) is formed in accordance with a position and size of a core end surface of a reference optical fiber (70) on an attachment / detachment end surface side of a reference connector plug (300) for waveguide production.

Description

Optical connector and method of manufacturing optical connector plug

[0001] The present disclosure relates to an optical connector and a method for manufacturing an optical connector plug.

[0002] With the spread of the Internet, the transmission capacity of information networks is expanding year by year. Methods for expanding the transmission capacity of optical fibers include time division multiplexing, wavelength division multiplexing, and space division multiplexing. In particular, space division multiplexing is a technology that achieves large capacity by arranging multiple cores or multiple modes in a single optical fiber. With single-mode uncoupled multicore fibers, by using an interface such as fine-in-fan-out, it is possible to expand the transmission capacity using conventional transceiver devices as is.

[0003] Furthermore, one method for increasing transmission capacity is mode-division multiplexing, which increases capacity by placing multiple propagation modes in one core and transmitting different signals in each mode. This technology uses an interface such as fine-in-fan-out to use each mode in each core as a different signal transmission path, thereby increasing transmission capacity.

[0004] In order to utilize space division multiplexing transmission technology in data centers, access networks, etc., it is necessary to lay multicore fiber optical cables that serve as transmission paths for space division multiplexing transmission. In order to maintain the scalability of laying multicore fiber cables, optical connectors that can connect multicore fibers are required. In multicore fiber connector technology, the fiber cores are positioned off-center with respect to the outer diameter of the fiber, so they need to be mounted with rotational alignment to achieve low connection loss. Non-Patent Documents 1 and 2 have proposed technologies for achieving low connection loss.

[0005] Satoshi Morishima, Yuki Saito, Osamu Shimakawa, Masaru Manabe, Tetsuya Nakanishi, Tomomi Sano, Tetsuya Hayashi, "Multicore Fiber Splicing Technology," IEICE General University, BCI-1-5, 2021. Hidetaka Terasawa, Takeshi Yukikawa, Keisuke Kondo, Okihiro Sugihara, "Fabrication of Near-Infrared Self-Written Optical Waveguides and Their Application to Multichannel Optical Waveguides," IEICE General University, C-13-2, 2013.

[0006] (1) Regarding single-mode connectors with one core propagation mode Non-Patent Document 1 describes a method for suppressing rotational misalignment when fabricating a single-core or multi-core connector plug for connecting multicore fibers. However, this technology requires precise alignment, including rotational alignment, and has the problem of requiring the use of parts and rotational alignment methods with higher precision than conventional connectors.

[0007] Non-Patent Document 2 describes a technique for connecting specific combinations of multicore fibers using self-forming waveguides. However, since optical connectors are required to be connectable in any combination, cores need to be arranged in standardized design target positions, but does not describe a method for arranging cores in the design target positions.

[0008] (2) Mode multiplexing transmission with multiple core propagation modes When connecting cores with multiple propagation modes, mode conversion may occur at the optical connection point even if no optical loss occurs. In mode multiplexing transmission, different signals are transmitted in each mode, so if mode conversion occurs, the signals will interfere with each other, leading to signal degradation.

[0009] The technology in Non-Patent Document 1 discloses a splice performance of 0.07 dB on average for splicing single-mode cores. For example, if a two-mode core is used and the splice loss between the fundamental modes is 0.07 dB, and that loss is due to mode conversion from the fundamental mode to a higher-order mode, the extinction ratio (the ratio of the fundamental mode propagating light before the splice point to the light converted to the higher-order mode) is -18 dB. For example, in wavelength multiplexing transmission, wavelength multiplexing / demultiplexing devices require an extinction ratio of -30 dB or less, so an extinction ratio of -18 dB can be considered high for multiplexed transmission. As described above, the technology in Non-Patent Document 1 has issues with mode conversion.

[0010] Furthermore, in the technology of Non-Patent Document 2, it is necessary to place the core at the design target position of the optical connector, but there is no description of a method for placing the core at the design target position.

[0011] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide an optical connector capable of connecting optical fibers with low loss, and a method for manufacturing an optical connector plug.

[0012] One aspect of the present disclosure is an optical connector having a waveguide formed using a photocurable resin, one end of the waveguide being connected to a core end face of an optical fiber inserted and fixed into an optical connector plug, and capable of transmitting an optical signal from the core of the optical fiber to the other end, the end face of the other end being formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug for waveguide fabrication.

[0013] One aspect of the present disclosure is an optical connector having a waveguide formed using a photocurable resin, one end of the waveguide being connected to a core end face of an optical fiber inserted and fixed into an optical connector plug, and capable of transmitting an optical signal from the optical fiber core to the other end, and the end face of the other end of the waveguide being formed according to the position and size of a light-transmitting hole in a photomask used to fabricate the waveguide.

[0014] One aspect of the present disclosure is a method for manufacturing an optical connector plug for use in an optical connector, the optical connector plug having a ferrule capable of holding a connection end of an optical fiber and photocurable resin, the connection end of the optical fiber inserted and fixed into the ferrule, the photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber, and a sealant forming a detachable end face of the ferrule and preventing the photocurable resin from leaking out, wherein an end face of a reference optical fiber inserted and fixed into a reference connector plug is arranged opposite the detachable end face of the ferrule, and light of a wavelength that increases the refractive index of the photocurable resin and hardens the photocurable resin is irradiated from the core of the optical fiber onto the photocurable resin, and light of the same wavelength is irradiated from the core of the reference optical fiber onto the photocurable resin, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening the resin, thereby forming a waveguide, and the end face of the waveguide on the detachable end face side is formed in accordance with the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug.

[0015] One aspect of the present disclosure is a method for manufacturing an optical connector plug for use in an optical connector, the optical connector plug having a ferrule capable of holding a connection end of an optical fiber and photocurable resin, the connection end of the optical fiber inserted and fixed within the ferrule, the photocurable resin filled within the ferrule so as to abut against the connection end of the optical fiber, and a sealant that forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out, wherein light of a wavelength that increases the refractive index of the photocurable resin and hardens it is irradiated from the core of the optical fiber to the photocurable resin, and light of the wavelength is irradiated from the detachable end face side to the photocurable resin through a photomask, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening it, thereby forming a waveguide, and the end face of the waveguide on the detachable end face side is formed according to the position and size of the light-transmitting hole of the photomask.

[0016] According to the present disclosure, it is possible to provide an optical connector capable of connecting optical fibers with low loss, and a method for manufacturing an optical connector plug.

[0017] FIG. 1 is a diagram showing the structure of an optical connector plug of an optical connector. FIG. 2 is a diagram showing a modified example of a sealing material of an optical connector plug. FIG. 3 is a diagram showing an example of an arrangement of multiple optical fibers in an optical connector plug. FIG. 4 is a diagram showing a modified example of an arrangement member of an optical connector plug. FIG. 5 is a diagram showing an example of a connection configuration of an optical connector. FIG. 6 is a diagram showing another example of a connection configuration of an optical connector. FIG. 7 is a diagram explaining a first method of manufacturing an optical connector plug. FIG. 8 is a diagram showing a waveguide of the optical connector plug shown in FIG. 7. FIG. 9 is a diagram showing a modified example of the first method of manufacturing an optical connector plug. FIG. 10 is a diagram showing a second method of manufacturing an optical connector plug. FIG. 11 is a diagram showing a method of manufacturing an optical connector plug for connecting a multicore fiber. FIG. 12 is a diagram showing a waveguide of the optical connector plug shown in FIG. 11. FIG. 13 is a diagram showing an example of an optical connector plug structure of a single-core optical connector. FIG. 14 is a diagram showing a modified example of a sealing material of an optical connector plug of a single-core optical connector. FIG. 15 is a diagram showing an example of a connection configuration of a single-core optical connector. FIG. 16 is a diagram explaining a first method of manufacturing an optical connector plug of a single-core optical connector. Fig. 17 is a diagram showing a waveguide of the optical connector plug shown in Fig. 16. Fig. 18 is a diagram explaining a second method for producing an optical connector plug for a single-core optical connector. Fig. 19 is a diagram explaining a method for producing an optical connector plug for a single-core optical connector to which a multi-core fiber is connected. Fig. 20 is an enlarged view of a portion of the optical connector plug shown in Fig. 19.

[0018] Next, several embodiments will be described in detail with reference to the drawings. In the description, the same components are designated by the same reference numerals and duplicated explanations will be omitted.

[0019] The first and second embodiments describe single mode embodiments, and the third and fourth embodiments describe multimode embodiments.

[0020] [First embodiment] Fig. 1 is a diagram showing an example of the structure of a connector plug of an optical connector according to a first embodiment. Fig. 1 is a cross-sectional view (side cross-sectional view) of an optical connector plug 100 taken along a plane parallel to the longitudinal direction of an optical fiber 10.

[0021] The optical connector of this embodiment includes optical connector plugs 100, each of which has a waveguide formed using a photocurable resin 13. One end of the waveguide is connected to a core end face of an optical fiber 10 inserted and fixed in the optical connector plug 100, and the waveguide is capable of transmitting an optical signal from the core of the optical fiber 10 to the other end. The end face of the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used for waveguide fabrication. The end face of the other end of the waveguide may also be formed according to the position and size of a light-transmitting hole in a photomask used for waveguide fabrication. The optical connector plug 100 may also include a ferrule 11 capable of holding the connection end of the optical fiber 10 and the photocurable resin 13, and a sealant 14 that forms the detachable end face of the ferrule 11 and prevents the photocurable resin from leaking. The photocurable resin 13 is filled in the ferrule 11 so as to abut against the connection end of the optical fiber 10.

[0022] The illustrated optical connector plug 100 includes connection ends of a plurality of optical fibers 10 inserted and fixed in a ferrule 11, the ferrule 11, an adhesive 12, a photocurable resin 13 that forms a self-forming optical waveguide (hereinafter referred to as "waveguide"), a sealing material 14, and an alignment member 16. The end face 15 of the ferrule 11 may be formed at an angle.

[0023] The optical connector plug 100 is a multi-fiber optical connector plug, and may be, for example, an F12-type multi-fiber optical fiber connector (MT connector). Alternatively, an F13-type multi-fiber optical fiber connector (MPO connector) may be used as the optical connector plug 100. In this case, the end face of the MT ferrule may be formed at an angle. The MT ferrule is housed in an MPO plug housing, and the MPO plug is connected within an MPO adapter. The multi-fiber optical connector is not limited to an MT connector or an MPO connector, as long as it can connect multiple optical fibers in a detachable manner.

[0024] The photocurable resin 13 is connected to the optical fiber 10 inside the ferrule 11. A waveguide capable of transmitting an optical signal is formed in the photocurable resin 13. The ferrule 11 is filled with the photocurable resin 13.

[0025] The sealing material 14 is provided on the ferrule end surface 15 and prevents the photocurable resin 13 from flowing out of the ferrule 11. The sealing material 14 holds the photocurable resin 13 inside the ferrule 11. The sealing material 14 forms the attachment / detachment end surface of the ferrule 11. The sealing material 14 is also referred to as the attachment / detachment end surface.

[0026] The sealing material 14 may be disposed in a shape that protrudes from the ferrule end face 15, as shown in Fig. 1. Alternatively, as shown in Fig. 2, a portion of the ferrule end face 15 may be recessed, and the sealing material 14 may be embedded in the ferrule end face 15. The sealing material 14 may have any shape and may be disposed in any manner as long as it is possible to prevent the photocurable resin 13 from leaking out from the ferrule end face 15.

[0027] For example, glass or resin may be used for the sealing material 14. The sealing material 14 may have any shape as long as it can emit light propagating through the waveguide formed in the photocurable resin 13 or propagate incident light through the waveguide. When a glass material is used for the sealing material 14, the waveguide formed in the photocurable resin 53 and the waveguide capable of transmitting an optical signal may be formed in the sealing material 14 by laser drawing.

[0028] Fig. 3 is a diagram for explaining a plurality of optical fibers 10 arranged in the optical connector plug 100. Fig. 3 is a cross-sectional view of the optical connector plug 100 cut along a plane perpendicular to the longitudinal direction of the optical fibers 10. The cross-sectional view shown is a cross-sectional view of a region where the adhesive 12 and the alignment member 16 are present.

[0029] The optical fibers 10 are arranged at equal intervals by an aligning member 16 toward the ferrule end face 15, and are adhesively fixed to the ferrule 11 by an adhesive 12. The adhesive 12 is injected through a hole (not shown) provided in the top of the ferrule 11.

[0030] In order to arrange the optical fibers 10 at equal intervals, for example, V-grooves, semicircular grooves, circular holes, etc. are formed in the arrangement member 16. The shape formed in the arrangement member 16 may be any shape as long as it allows the optical fibers 10 to be arranged at equal intervals. In the example shown in Fig. 3, eight optical fibers 10 are arranged, but the number of optical fibers 10 is not limited to eight as long as it is two or more.

[0031] 4, the alignment member 16 may have a tapered shape to facilitate insertion of the optical fiber 10. The optical fiber 10 may be, for example, a single-core fiber, a multi-core fiber, or a polarization-maintaining fiber, as long as it is an optical fiber that transmits light of any wavelength.

[0032] 5 is a diagram showing an example of a connection configuration of the optical connector 200 of this embodiment. Here, axial alignment is performed by inserting a guide pin (not shown) into a guide hole (not shown) arranged on the ferrule end face 15, and a pressing force is applied to the opposing optical connector plugs 100 by a spring (not shown), causing the sealing materials 14 (attachment / detachment end faces) to tightly contact each other to form the optical connector 200. This allows the optical fibers 10 inserted and fixed in the opposing optical connector plugs 100 to be connected with low loss.

[0033] 6, a refractive index matching material 18 may be applied between the opposing sealing materials 14. The refractive index matching material 18 may be in a gel or solid state. When a solid refractive index matching material 18 is used, there is no need to remove and reapply the refractive index matching material 18 when connecting or disconnecting the optical connector, which reduces the amount of work required for connecting or disconnecting the optical connector.

[0034] 7 is a diagram illustrating a first method for fabricating the optical connector plug 100 used in the optical connector 200 of this embodiment. In the first fabrication method, the end face of the reference optical fiber 30 inserted and fixed in the reference connector plug 300 is positioned opposite the detachable end face 14 of the ferrule 11, and light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens the resin is irradiated from the core of the optical fiber 10 onto the photocurable resin 13, while light of the same wavelength is irradiated from the core of the reference optical fiber 30 onto the photocurable resin 13, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 30 on the detachable end face side of the reference connector plug 300.

[0035] Specifically, a hollow portion connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14) is filled with photocurable resin 13. Then, a reference connector plug 300 for fabricating a waveguide is connected to the optical connector plug 100 of the optical connector 200. The reference connector plug 300 includes a plurality of optical fibers 30 (reference optical fibers), a ferrule 31, an adhesive 32, and an alignment member 36. The optical fiber 30 has a core 30a and a cladding 30b.

[0036] Then, light sources 19 and 39 with wavelengths that increase the refractive index of the photocurable resin 13 and harden it are connected to the optical fiber 10 of the optical connector plug 100 and the optical fiber 30 of the reference connector plug 300, respectively. Light with the wavelength is then irradiated from the cores 10a and 30a of the optical fibers 10 and 30, respectively. This increases the refractive index of the irradiated portion of the photocurable resin 13 and hardens it, resulting in the creation of a waveguide 20 as shown in FIG. 8. FIG. 8 is an enlarged view of a portion of the cross-sectional view of the optical connector plug 100 shown in FIG. 1. That is, the end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 30 on the detachable end face side of the reference connector plug 300. After the waveguide 20 is created, the reference connector plug 300 and the light source 19 are removed, thereby completing the optical connector plug 100.

[0037] In this way, the end face on the detachable end face side of the waveguide 20 fabricated by the first fabrication method is formed according to the core end face of the reference connector plug 300, and therefore the end face on the detachable end face side of the waveguide 20 of an optical connector plug 100 fabricated using the same reference connector plug 300 has the same shape and size and is formed at the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 fabricated by the first fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated.

[0038] 9 , a cladding 21 may be formed around the waveguide 20. After the waveguide 20 is formed, the photocurable resin 13 may be removed from the portion where the waveguide 20 is not formed, and the ferrule 11 may be filled with another photocurable resin 13b capable of forming a cladding having a lower refractive index than the waveguide 20. Light having a wavelength that causes the other photocurable resin 13b to harden may be irradiated from the ferrule end face 15 side, thereby hardening the other photocurable resin 13b, thereby forming the cladding 21 around the waveguide 20.

[0039] Specifically, the photocurable resin 13 is removed from the injection port 22 provided in the ferrule 11, and instead photocurable resin 13b that can be irradiated with light to form a cladding 21 having a lower refractive index than the waveguide 20 is injected. Then, a light source 37 with a wavelength that causes the photocurable resin 13b to harden is disposed near the ferrule end face 15, and the cladding 21 may be formed by irradiating the photocurable resin 13b with light 37a of the wavelength from the light source 37. The injection port 22 may be provided in advance in the ferrule 11 for removing the photocurable resin 13 and injecting the photocurable resin 13b.

[0040] An optical connector plug used in a high-precision optical connector manufactured with minimal error from the design target of the optical connector may be used as the reference connector plug 300. In the case of a single-core fiber connector, a reference connector specified by the IEC (International Electrotechnical Commission) may be used.

[0041] In the case of a multicore fiber connector without a reference connector, an optical connector with low connection loss may be selected, for example, using the following procedure. A plurality of optical connectors are fabricated in which the core positions are aligned so that there is little error from the design target by image alignment or the like, and those with small errors are selected from among them to extract sample group A. Another plurality of optical connectors are fabricated in which the core positions are aligned, and those with small errors are selected from among them to extract sample group B, which is different from sample group A. A plurality of optical connectors are fabricated in which the core positions are aligned, and those with small errors are selected from among them to extract sample group C, which is different from sample groups A and B. The optical connectors of sample groups A, B, and C are then connected together to select an optical connector that achieves even lower connection loss. The optical connector plug of the optical connector selected in this manner may be used as the reference connector plug 300.

[0042] 10 is a diagram illustrating a second manufacturing method for the optical connector plug 100 according to the first embodiment. In the second manufacturing method, the photocurable resin 13 is irradiated with light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens the resin from the core of the optical fiber 10, and the photocurable resin 13 is also irradiated with light of the wavelength from the attachment / detachment end face side through a photomask 42, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the attachment / detachment end face side is formed according to the position and size of the light transmission hole in the photomask 42.

[0043] Specifically, in the second fabrication method, instead of using the reference connector plug 300, photolithography using a photomask 42 and a light source 38 is used. The hollow portion connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14) is filled with photocurable resin 13. Then, the photomask 42 and a light source 38 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it are placed near the ferrule end face 15 of the optical connector plug 100. In addition, a light source 19 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is connected to the optical fiber 10 of the optical connector plug 100.

[0044] By irradiating the photocurable resin 13 with light of a wavelength that increases the refractive index and hardens the resin from the core 10a of the optical fiber 10 and the photomask 42, respectively, the refractive index of the irradiated portion of the photocurable resin 13 increases and hardens, thereby generating a waveguide 20.

[0045] The photomask 42 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 42 may have any structure as long as the light-transmitting holes allow light to pass through and the remaining portions block light. The photomask 42 may have, for example, a structure in which holes are drilled in a metal plate or a structure in which metal is vapor-deposited on the surface of a glass plate. The end face of the waveguide 20 on the detachable end face 14 side is formed according to the position and size of the light-transmitting holes in the photomask 42. After the waveguide 20 is formed, the photomask 42 and the light sources 19 and 38 are removed to produce the optical connector plug 100.

[0046] Since the end face on the detachable end face side of the waveguide 20 fabricated by the second fabrication method is formed according to the light-transmitting holes of the photomask 42, the end face on the detachable end face side of the waveguide 20 of an optical connector plug 100 fabricated using the same photomask 42 will have the same shape and size and be formed at the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 fabricated by the second fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated. Note that the cladding 21 may also be formed in the second fabrication method in the same way as in the first fabrication method.

[0047] In this embodiment, the waveguide 20 is formed using the reference connector plug 300 or photolithography technology, but the method is not limited to these as long as it is possible to fabricate the waveguide 20 so that the core position of the optical connector plug 100 has a small error from the design target.

[0048] 11 is a diagram illustrating a method for fabricating an optical connector plug 100 for connecting a multicore fiber. Here, a method for fabricating the optical connector plug 100 using the first fabrication method described above will be described as an example. A reference connector plug 300 is connected to the optical connector plug 100. The optical fiber 10 of the optical connector plug 100 and the optical fiber 30 of the reference connector plug 300 are each connected to a single-core fiber 40 via a fan-out 41. Light sources 19, 39 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it are connected to each single-core fiber 40, and light of the wavelength is irradiated from the cores 10a, 30a of the optical fibers 10, 30.

[0049] This causes an increase in the refractive index and hardening of the light-irradiated portion of the photocurable resin 13, forming a plurality of waveguides 20 as shown in FIG. 12. After the waveguides 20 are formed, the reference connector plug 300 and the fan-out 41 are removed to produce the optical connector plug 100. By connecting two optical connector plugs 100 produced using the same reference connector plug 300, it is possible to produce an optical connector that can connect optical fibers with low loss. Although FIGS. 11 and 12 show an example of a multicore fiber having four cores, the number of cores in the multicore fiber may be two or more, and the core arrangement may be any desired arrangement.

[0050] [Second embodiment] Fig. 13 is a diagram showing an example of a connector plug structure of an optical connector according to a second embodiment. Fig. 13 is a cross-sectional view (side cross-sectional view) of an optical connector plug 500 cut along a plane parallel to the longitudinal direction of an optical fiber 50.

[0051] The optical connector of this embodiment includes optical connector plugs 500, each of which has a waveguide formed using a photocurable resin 53. One end of the waveguide is connected to a core end face of an optical fiber 50 inserted and fixed in the optical connector plug 500, and the optical signal from the core of the optical fiber 50 can be transmitted to the other end. The end face of the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used for waveguide fabrication. The end face of the other end of the waveguide may also be formed according to the position and size of a light-transmitting hole in a photomask used for waveguide fabrication. The optical connector plug 500 may include a ferrule 51 capable of holding the connecting end of the optical fiber 50 and the photocurable resin 53, and a sealant 54 that forms the detachable end face of the ferrule 51 and prevents the photocurable resin from leaking. The photocurable resin 53 is filled in the ferrule 51 so as to abut against the connecting end of the optical fiber 50.

[0052] The illustrated optical connector plug 500 is a single-core optical connector plug, and includes a connection end of a single optical fiber 50 inserted and fixed in a ferrule 51, the ferrule 51, a plug frame 52, a photocurable resin 53 that forms a self-forming optical waveguide (waveguide), a sealant 54, a tab 56, a flange 57, a spring 58, and a stop ring 59. The sealant 54 is disposed on a ferrule end face 55 to prevent the photocurable resin 53 filled in the ferrule 51 from leaking out.

[0053] An F04 type optical fiber connector (SC connector) may be used as the single-core optical connector plug 500. Also, an F14 type optical fiber connector (MU connector) may be used as the optical connector plug 500 instead of the SC connector.

[0054] The optical connector plug 500 may have any shape as long as the single-core optical fiber 50 adhesively fixed to the ferrule 51 can be connected to an opposing optical fiber via an adapter (not shown). That is, the presence or absence of the flange 57, spring 58, stop ring 59, plug frame 52, and knob 56, as well as their shapes, are not limited to those shown in Figure 13. The single-core optical connector of this embodiment is not limited to an SC connector or an MU connector as long as it can detachably connect a single-core optical fiber.

[0055] The photocurable resin 53 is connected to the optical fiber 50 inside the ferrule 51 to form a self-written optical waveguide capable of transmitting an optical signal. The photocurable resin 53 is prevented from flowing out of the ferrule end face 55 by the sealing material 54, and is held inside the ferrule 51.

[0056] The sealing material 54 may be disposed in a shape that protrudes from the ferrule end face 55 as shown in FIG. 13 , or may be disposed in a shape that is recessed into the ferrule end face 55 as shown in FIG. 14 . The sealing material 54 may have any shape and be disposed in any position as long as it can prevent the photocurable resin 53 from leaking out of the ferrule end face 55. For example, glass, resin, or the like may be used for the sealing material 54. The sealing material 54 may have any shape as long as it can emit light propagating through the waveguide formed in the photocurable resin 53 or propagate incident light into the waveguide. When a glass material is used for the sealing material 54, the waveguide formed in the photocurable resin 53 and a waveguide capable of transmitting an optical signal may be formed in the sealing material 54 by laser drawing.

[0057] The single-core optical fiber 50 may be, for example, a single-core fiber, a multi-core fiber, a polarization-maintaining fiber, or the like, as long as it is an optical fiber that transmits light of an arbitrary wavelength.

[0058] 15 is a diagram showing an example of a connection configuration of an optical connector according to the second embodiment. Axial alignment is performed by inserting two opposing ferrules 51 into a sleeve 63 attached to an adapter (not shown). Then, a pressing force is applied to the optical fiber 50 and the ferrule end face 55 by a spring 58, forming an optical connector 600 in a configuration in which the sealing materials 54 are in close contact with each other, and the optical fiber 50 is connected.

[0059] To reduce return loss, a refractive index matching material (not shown) may be applied between the sealing materials 54. The refractive index matching material may be in a gel or solid state. When a solid refractive index matching material is used, there is no need to remove and reapply the matching material when connecting or disconnecting the optical connector, which reduces the amount of work required for connecting or disconnecting the optical connector.

[0060] 16 is a diagram illustrating a first method for fabricating the optical connector plug 500 of the second embodiment. In the first fabrication method, the end face of the reference optical fiber 70 inserted and fixed in the reference connector plug 700 is positioned opposite the detachable end face 54 of the ferrule 51, and light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens the resin is irradiated from the core of the optical fiber 50 to the photocurable resin 53, while light of the same wavelength is irradiated from the core of the reference optical fiber 70 to the photocurable resin 53, thereby increasing the refractive index of the irradiated portion of the photocurable resin 53 and hardening the resin, thereby forming the waveguide 60. The end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 70 on the detachable end face side of the reference connector plug 700.

[0061] Specifically, a photocurable resin 53 is filled into the hollow space connecting the end face of the optical fiber disposed in the ferrule 51 and the ferrule end face 55 (detachable end face 54). Then, a reference connector plug 700 is connected to the optical connector plug 500. Light sources 69 and 89 with wavelengths that increase the refractive index of the photocurable resin 53 and harden it are connected to the optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700, respectively, and light of the wavelength is irradiated onto the photocurable resin 53 from the cores 50 a and 70 a of the optical fibers 50 and 70. This increases the refractive index of the irradiated portion of the photocurable resin 53 and hardens it, forming a waveguide 60 as shown in FIG. 17 . That is, the end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 70 on the detachable end face side of the reference connector plug 700. After the waveguide 60 is created, the reference connector plug 700 and the light source 69 are removed, thereby producing the optical connector plug 500 .

[0062] In this way, the end face on the detachable end face side of the waveguide 60 fabricated by the first fabrication method is formed according to the core end face of the reference connector plug 700, and therefore the end face on the detachable end face side of the waveguide 60 of an optical connector plug 500 fabricated using the same reference connector plug 700 has the same shape and size and is formed at the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 fabricated by the first fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated.

[0063] After the waveguide 60 is produced, a cladding may be formed in the same manner as in the first manufacturing method of the first embodiment. Specifically, after the waveguide is produced, the photocurable resin 53 is removed from an injection port (not shown) formed in the ferrule 51, and instead a photocurable resin capable of forming a cladding having a lower refractive index than the waveguide by light irradiation is injected. A light source with a wavelength that causes the photocurable resin for the cladding to harden may be prepared, and the cladding may be formed by irradiating light from the light source.

[0064] An optical connector plug used in a high-precision optical connector manufactured with minimal error from the design target of the optical connector may be used as the reference connector plug 700. In the case of a single-core fiber connector, a reference connector specified by the IEC (International Electrotechnical Commission) may be used.

[0065] In the case of a multicore fiber connector without a reference connector, an optical connector with low connection loss may be selected, for example, using the following procedure. A plurality of optical connectors are fabricated in which the core positions are aligned so that there is little error from the design target by image alignment or the like, and those with small errors are selected from among them to extract sample group A. Another plurality of optical connectors are fabricated in which the core positions are aligned, and those with small errors are selected from among them to extract sample group B, which is different from sample group A. A plurality of optical connectors are fabricated in which the core positions are aligned, and those with small errors are selected from among them to extract sample group C, which is different from sample groups A and B. The optical connectors of sample groups A, B, and C are then connected together to select an optical connector that achieves even lower connection loss. The optical connector plug of the optical connector selected in this manner may be used as the reference connector plug 700.

[0066] 18 is a diagram illustrating a second method for manufacturing the optical connector plug 500 of the second embodiment. In the second manufacturing method, the photocurable resin 53 is irradiated with light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it from the core of the optical fiber 50, and the photocurable resin 53 is also irradiated with light of the same wavelength from the attachment / detachment end face side through a photomask 62, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 53, thereby forming the waveguide 60. The end face of the waveguide 60 on the attachment / detachment end face side is formed according to the position and size of the light transmission hole in the photomask 62.

[0067] Specifically, in the second fabrication method, instead of using the reference connector plug 700, photolithography using a photomask 62 and a light source 88 is used. A hollow portion connecting the end face of the optical fiber placed in the ferrule 51 and the ferrule end face 55 (detachable end face 54) is filled with photocurable resin 53. Then, a photomask 62 and a light source 88 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are placed near the ferrule end face 55 of the optical connector plug 500. In addition, a light source 69 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is connected to the optical fiber 50 of the optical connector plug 500.

[0068] By irradiating light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens it from the core 50a of the optical fiber 50 and the photomask 62, respectively, the refractive index of the irradiated portion of the photocurable resin 53 increases and hardens, thereby generating a waveguide 60.

[0069] The photomask 62 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 62 may have any structure as long as the light-transmitting holes allow light to pass through and the remaining portions block light. The photomask 62 may have, for example, a structure in which holes are drilled in a metal plate or a structure in which metal is vapor-deposited on the surface of a glass plate. The end face of the waveguide 60 on the detachable end face 54 side is formed according to the position and size of the light-transmitting holes in the photomask 62. After the waveguide 60 is formed, the photomask 62 and the light sources 69 and 88 are removed to produce the optical connector plug 500.

[0070] Since the end face on the detachable end face side of the waveguide 60 fabricated by the second fabrication method is formed according to the light transmitting holes of the photomask 62, the end face on the detachable end face side of the waveguide 60 of an optical connector plug 500 fabricated using the same photomask 62 will have the same shape and size and be formed at the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 fabricated by the second fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated. Note that the cladding may also be formed in the second fabrication method as in the first fabrication method.

[0071] In this embodiment, the waveguide 20 is formed using the reference connector plug 700 or photolithography technology, but the method is not limited to these as long as it is possible to fabricate the waveguide 20 so that the core position of the optical connector plug 100 has a small error from the design target.

[0072] 19 is a diagram illustrating a method for fabricating an optical connector plug 500 for connecting a multicore fiber. Here, a method for fabricating the optical connector plug 500 using the first fabrication method described above will be described as an example. A reference connector plug 700 is connected to the optical connector plug 500.

[0073] The optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700 are each connected to a single-core fiber 80 via a fan-out 61. Light sources 69, 89 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are connected to each single-core fiber 80, and light of the wavelength is irradiated onto the photocurable resin 53 from the cores 50 a, 70 a of the optical fibers 50, 70.

[0074] This causes an increase in the refractive index and hardening of the photocurable resin 13 in the irradiated portions, resulting in the creation of a plurality of waveguides 60 as shown in Fig. 20. After the waveguides 60 are created, the reference connector plug 700 and the fan-out 61 are removed to create the optical connector plug 500. By connecting two optical connector plugs 500 created using the same reference connector plug 700, it is possible to create an optical connector that can connect optical fibers with low loss. Although Figs. 19 and 20 show an example of a multicore fiber having four cores, the number of cores in the multicore fiber may be two or more, and the core arrangement may be any arbitrary arrangement.

[0075] [Third Embodiment] Figure 13 is a diagram showing an example of a connector plug structure of an optical connector according to a third embodiment. The connector plug structure of this embodiment is similar to the connector plug structure of the second embodiment described above. That is, the optical connector plug 500 of this embodiment has a waveguide formed using a photocurable resin 53, one end of which is connected to the core end face of an optical fiber 50 inserted and fixed in the optical connector plug 500, and which is capable of transmitting an optical signal from the core of the optical fiber 50 to the other end. The end face of the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug used for waveguide fabrication. Furthermore, the end face of the other end of the waveguide may be formed according to the position and size of a light-transmitting hole in a photomask used for waveguide fabrication. The optical connector plug 500 may also include a ferrule 51 capable of holding the connection end of the optical fiber 50 and the photocurable resin 53, and a sealant 54 that forms the detachable end face of the ferrule 51 and prevents the photocurable resin from leaking. The photocurable resin 53 is filled into the ferrule 51 so as to abut against the connection end of the optical fiber 50 .

[0076] The optical connector plug 500 of the illustrated embodiment is a single-core optical connector plug and includes a single optical fiber 50, a ferrule 51, a plug frame 52, a photocurable resin 53 that forms a self-forming optical waveguide (waveguide), a sealant 54 (detachable end face), a tab 56 (housing), a flange 57, a spring 58, and a stop ring 59. The sealant 54 is disposed on a ferrule end face 55 to prevent the photocurable resin 53 filled in the ferrule 51 from leaking out. The single-core optical connector plug 500 can be, for example, an SC connector, an MU connector, or other optical connector plug, but is not limited to these.

[0077] The optical connector plug 500 may have any shape as long as the single-core optical fiber 50 adhesively fixed to the ferrule 51 can be connected to an opposing optical fiber via an adapter (not shown). That is, the presence or absence of the flange 57, spring 58, stop ring 59, plug frame 52, and knob 56, as well as their shapes, are not limited to those shown in Figure 16. The single-core optical connector of this embodiment is not limited to an SC connector or an MU connector as long as it can connect a single-core optical fiber in a detachable manner.

[0078] The photocurable resin 53 is connected to the optical fiber 50 inside the ferrule 51 to form a self-written optical waveguide capable of transmitting an optical signal. The photocurable resin 53 is prevented from flowing out of the ferrule end face 55 by the sealing material 54, and is held inside the ferrule 51.

[0079] One end of the waveguide is connected to the core end face of the optical fiber 50, and the other end is connected to the sealing material 54, which is the detachable end face. That is, the optical waveguide in the photocurable resin 53 is formed so as to connect the end face of the optical fiber 50 to the design target position of the optical connector core on the detachable end face 54.

[0080] The sealing material 54 may be disposed in a shape that protrudes from the ferrule end face 55 as shown in FIG. 16 , or may be disposed in a shape that is embedded in the ferrule end face 55 by making the ferrule end face 55 concave as shown in FIG. 17 . The sealing material 54 may have any shape and be disposed in any position as long as it can prevent the photocurable resin 53 from leaking out from the ferrule end face 55. For example, glass, resin, or the like may be used for the sealing material 54. The sealing material 54 may have any shape as long as it can emit light propagating through the waveguide formed in the photocurable resin 53 or propagate incident light into the waveguide. A waveguide formed in the photocurable resin 53 and a waveguide capable of transmitting an optical signal may be formed in the sealing material 54 by laser drawing.

[0081] The single-core optical fiber 50 of this embodiment may be, for example, a single-core multimode fiber or a multi-core multimode fiber, as long as it is an optical fiber that transmits light of any wavelength in multiple propagation modes. In this embodiment, a case where a multi-core multimode fiber is used will be described.

[0082] 16 will be used to explain a first method for fabricating the optical connector plug of this embodiment. In the first fabrication method, the end face of the reference optical fiber 70 inserted and fixed in the reference connector plug 700 is positioned opposite the detachable end face 54 of the ferrule 51, and light of a wavelength that increases the refractive index of the photocurable resin 53 and hardens the resin is irradiated from the core of the optical fiber 50 onto the photocurable resin 53, while light of the same wavelength is irradiated from the core of the reference optical fiber 70 onto the photocurable resin 53, thereby increasing the refractive index of the irradiated portion of the photocurable resin 53 and hardening the resin, thereby forming a waveguide 60. The end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 70 on the detachable end face side of the reference connector plug 700.

[0083] Specifically, a photocurable resin 53 is filled into the hollow space connecting the end face of the optical fiber disposed in the ferrule 51 and the ferrule end face 55 (detachable end face 54). Then, a reference connector plug 700 is connected to the optical connector plug 500. Light sources 69 and 89 with wavelengths that increase the refractive index of the photocurable resin 53 and harden it are connected to the optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700, respectively, and light of the wavelength is irradiated onto the photocurable resin 53 from the cores 50 a and 70 a of the optical fibers 50 and 70. This increases the refractive index and hardens the irradiated portion of the photocurable resin 53, forming a waveguide 60 as shown in FIG. 17 . That is, the end face of the waveguide 60 on the detachable end face side is formed according to the position and size of the core end face of the optical fiber 70 on the detachable end face side of the reference connector plug 700. After the waveguide 60 is created, the reference connector plug 700 and the light source 69 are removed, thereby producing the optical connector plug 500 .

[0084] In this way, the end face on the detachable end face side of the waveguide 60 fabricated by the first fabrication method is formed according to the core end face of the reference connector plug 700, and therefore the end face on the detachable end face side of the waveguide 60 of an optical connector plug 500 fabricated using the same reference connector plug 700 has the same shape and size and is formed at the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 fabricated by the first fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated.

[0085] A high-precision connector manufactured with a small error in the core position of the optical connector from the design target may be used as the reference connector plug 700. If an appropriate high-precision connector is not available, for example, as described in the second embodiment, a plurality of optical connectors are manufactured in which the core position is aligned by image alignment or the like so that the error from the design target is small, and from these, those with small errors are selected by end face image inspection or the like to extract three sample groups A, B, and C. The optical connectors in each sample group are connected to each other to select connector combinations that achieve lower connection loss, and the optical connector plugs of the selected optical connectors may be used as the reference connector plug 700.

[0086] The light sources 69 and 89 may have the same wavelength as the communication light to be transmitted through the optical connector, and may propagate in the same propagation mode as the propagation mode used for communication to generate the waveguide 60. As a method for this, for example, when connecting a multimode fiber using three propagation modes, LP01 mode, LP11 mode, and LP02 mode, there is a method in which the light output from the light sources 69 and 89 is first propagated in the optical fiber 50 in the LP01 mode to harden the photocurable resin 53, then propagated in the LP11 mode to harden the photocurable resin 53, and then propagated in the LP02 mode to harden the photocurable resin 53.

[0087] After the waveguide is created, the photocurable resin 53 is removed, and a photocurable resin capable of forming a cladding having a lower refractive index than the waveguide by light irradiation is injected, and a light source with a wavelength that causes the injected photocurable resin to harden is prepared, and the cladding can be formed by irradiating the injected photocurable resin with light of a wavelength that causes the injected photocurable resin to harden.

[0088] Alternatively, a photocurable resin 53 having the characteristic of being cured at two or more different wavelengths may be used to form a waveguide, and then a light source of a wavelength different from that used when the waveguide was formed may be used to cure the remaining uncured photocurable resin 53, thereby forming a cladding with a low refractive index.

[0089] The refractive index of the cladding changes depending on whether or not the cladding is cured, and if it is cured, the physical properties of the photocurable resin injected and the wavelength used for curing. A change in the refractive index of the cladding changes the mode field diameter of the light propagating through the formed waveguide. Taking advantage of this, after forming the waveguide, the loss and mode conversion state can be measured, and if necessary, the refractive index of the cladding can be changed to change the mode field diameter of the waveguide and improve the loss and mode conversion state.

[0090] The formed waveguide has an extremely fine structure and may be broken if an external force is applied. However, since the waveguide of this embodiment is formed within the ferrule 51 and the sealing material 54, it is protected from external forces by the ferrule 51. The ferrule 51 is protected from external forces by the plug frame 52. The plug frame 52 is protected from external forces by the tab 56. In this way, this embodiment can provide an optical connector in which the waveguide is less likely to be broken.

[0091] An example of a connection configuration of the optical connector according to the third embodiment will be described with reference to Figure 15. Axial alignment is performed by inserting two opposing ferrules 51 into a sleeve 63 attached to an adapter (not shown). Then, a pressing force is applied to the optical fiber 50 and the ferrule end face 55 by a spring 58, forming an optical connector 600 in a configuration in which the detachable end faces 54 are in close contact with each other, and the optical fiber 50 is connected. A refractive index matching material may be applied between the detachable end faces 54 to reduce return loss.

[0092] When using the sleeve 63 and ferrule 51, if components conforming to the international standard IEC 61755-3-1 are used, the maximum misalignment of the optical fiber core axis is 2.0 μm.

[0093] For example, a short waveguide distance of about 20 μm is sufficient to shift the core by 2.0 μm in a self-written optical waveguide. Because the waveguide is short, almost no optical loss occurs during propagation through the waveguide.

[0094] As described above, by using the optical connector 600 of this embodiment, it is possible to reduce the amount of axial misalignment of the optical fiber 50. As a result, the length of the waveguide required in the optical connector plug 500 can be shortened, and optical loss in the waveguide can be suppressed. Furthermore, in this embodiment, a waveguide is formed using light of the same wavelength and propagation mode as the communication light emitted from the core of the optical fiber 50. As a result, a waveguide having a shape that follows the shape of the communication light is formed, thereby suppressing propagation mode conversion within the waveguide.

[0095] 15 will be used to explain a second method for fabricating the optical connector plug of this embodiment. In the second fabrication method, light of a wavelength that increases the refractive index of photocurable resin 53 and hardens it is irradiated onto photocurable resin 53 from the core of optical fiber 50, and light of the wavelength is also irradiated onto photocurable resin 53 from the attachment / detachment end face side through a photomask 62, thereby increasing the refractive index and hardening the irradiated portion of photocurable resin 53, thereby forming waveguide 60. The end face of waveguide 60 on the attachment / detachment end face side is formed according to the position and size of the light transmission hole in photomask 62.

[0096] Specifically, in the second fabrication method, instead of using the reference connector plug 700, photolithography using a photomask 62 and a light source 88 is used. A hollow portion connecting the end face of the optical fiber placed in the ferrule 51 and the ferrule end face 55 (detachable end face 54) is filled with photocurable resin 53. Then, a photomask 62 and a light source 88 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are placed near the ferrule end face 55 of the optical connector plug 500. In addition, a light source 69 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it is connected to the optical fiber 50 of the optical connector plug 500.

[0097] By irradiating the core 50a of the optical fiber 50 with light of the above wavelength from the photomask 62, the refractive index of the irradiated portion of the photocurable resin 53 increases and the resin hardens, thereby producing the waveguide 60. After the waveguide 60 is produced, the photomask 62 and the light sources 69 and 88 are removed, and the optical connector plug 500 is fabricated.

[0098] The photomask 62 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 62 may have any structure as long as the light-transmitting holes allow light to pass through and the remaining portions block light. The photomask 62 may have, for example, a structure in which holes are drilled in a metal plate or a structure in which metal is vapor-deposited on the surface of a glass plate. The end face of the waveguide 60 on the detachable end face 54 side is formed according to the position and size of the light-transmitting holes in the photomask 62.

[0099] Since the end face on the detachable end face side of the waveguide 60 fabricated by the second fabrication method is formed according to the light transmitting holes of the photomask 62, the end face on the detachable end face side of the waveguide 60 of an optical connector plug 500 fabricated using the same photomask 62 will have the same shape and size and be formed at the same position on the ferrule end face 55. Therefore, by connecting two optical connector plugs 500 fabricated by the second fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated. Note that the cladding may also be formed in the second fabrication method as in the first fabrication method.

[0100] The light sources 69 and 88 may have the same wavelength as the communication light to be transmitted through the optical connector, and the light from the light sources 69 and 88 may be propagated in the same propagation mode as that used for communication to generate the optical waveguide 60.

[0101] 19 is a diagram illustrating a method for fabricating an optical connector plug 500 for connecting a multicore fiber. Here, a method for fabricating the optical connector plug 500 using the first fabrication method described above will be described as an example. A reference connector plug 700 is connected to the optical connector plug 500.

[0102] The optical fiber 50 of the optical connector plug 500 and the optical fiber 70 of the reference connector plug 700 are each connected to a single-core fiber 80 via a fan-out 61. Light sources 69, 89 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are connected to each single-core fiber 80, and light of the wavelength is irradiated onto the photocurable resin 53 from the cores 50 a, 70 a of the optical fibers 50, 70.

[0103] This causes an increase in the refractive index and hardening of the photocurable resin 53 in the irradiated portions, resulting in the creation of a plurality of waveguides 60 as shown in Fig. 20. After the waveguides 60 are created, the reference connector plug 700 and the fan-out 61 are removed to create the optical connector plug 500. By connecting two optical connector plugs 500 created using the same reference connector plug 700, it is possible to create an optical connector that can connect optical fibers with low loss. Although Figs. 19 and 20 show an example of a multicore fiber having four cores, the number of cores in the multicore fiber may be two or more, and the core arrangement may be any desired arrangement.

[0104] [Fourth Embodiment] Fig. 1 is a diagram showing an example of a connector plug structure of an optical connector according to a fourth embodiment. The optical connector plug 100 of this embodiment is a multi-fiber optical connector plug similar to the optical connector plug 100 of the first embodiment. The optical connector plug 100 of this embodiment has a waveguide formed using a photocurable resin 13, one end of which is connected to a core end face of an optical fiber 10 inserted and fixed in the optical connector plug 100, and which is capable of transmitting an optical signal from the core of the optical fiber 10 to the other end. The end face at the other end of the waveguide may be formed according to the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug for waveguide fabrication. Furthermore, the end face at the other end of the waveguide may be formed according to the position and size of a light-transmitting hole in a photomask for waveguide fabrication.

[0105] The optical connector plug 100 may include a ferrule 11 capable of holding the connection end of the optical fiber 10 and the photocurable resin 13, and a sealant 14 that forms the detachable end face of the ferrule 11 and prevents the photocurable resin 13 from leaking out. The photocurable resin 13 is filled in the ferrule 11 so as to abut against the connection end of the optical fiber 10.

[0106] The illustrated optical connector plug 100 includes connection ends of a plurality of optical fibers 10 inserted and fixed in a ferrule 11, the ferrule 11, an adhesive 12, a photocurable resin 13 that forms a self-forming optical waveguide, a sealing material 14 (detachable end face), and an arrangement member 16. The multi-fiber optical connector may be any multi-fiber optical connector that can detachably connect a plurality of optical fibers all at once, and is not limited to multi-fiber optical connectors such as MT connectors and MPO connectors.

[0107] The photocurable resin 13 is connected to the optical fiber 10 inside the ferrule 11, and a waveguide 20 capable of transmitting an optical signal is formed in the photocurable resin 13. One end of the waveguide 20 is connected to the end face of the core 10a of the optical fiber 10, and the other end is connected to the detachable end face 14. The waveguide 20 in the photocurable resin 13 is formed so as to connect the design target position of the optical connector core on the detachable end face 14 with the end face of the core 10a of the optical fiber 10.

[0108] The sealing material 14 may be disposed in a shape that protrudes from the ferrule end face 15 as shown in FIG. 1 , or may be disposed in a shape that is recessed into the ferrule end face 15 as shown in FIG. 2 . The sealing material 14 may have any shape that can prevent the photocurable resin 13 from leaking out from the ferrule end face 15. For example, glass or resin may be used for the sealing material 14, and the sealing material may have any shape that can emit light propagating through the waveguide 20 formed in the photocurable resin 13 or propagate incident light to the waveguide 20 formed in the photocurable resin 13. When a glass material is used for the sealing material 14, the waveguide formed in the photocurable resin 13 and the waveguide capable of transmitting an optical signal may be formed in the sealing material 14 by laser drawing.

[0109] As shown in Fig. 3, the optical fibers 10 are arranged at equal intervals by an arranging member 16 toward the ferrule end face 15, and are adhesively fixed to the ferrule 11 by adhesive 12 injected through a hole (not shown) provided in the top of the ferrule 11. In order to arrange the optical fibers 10 at equal intervals, the arranging member 16 is provided with, for example, a V-groove, a semicircular groove, a circular hole, or the like. However, the grooves and holes provided in the arranging member 16 may have any shape as long as they can arrange the optical fibers 10 at equal intervals. Although Fig. 4 shows eight optical fibers arranged, the number of optical fibers 10 is not limited to eight, and may be two or more.

[0110] The optical fibers 10 may be, for example, single-core multimode fibers or multi-core multimode fibers, and may be optical fibers that transmit light of any wavelength in multiple propagation modes. In this embodiment, a case where a multi-core multimode fiber is used will be described.

[0111] An example of a connection configuration of the optical connector 200 of this embodiment will be described using Figure 5. Here, axial alignment is performed by inserting a guide pin (not shown) into a guide hole (not shown) arranged on the ferrule end face 15, and a spring (not shown) applies a pressing force to the opposing optical connector plugs 100, causing the sealing materials 14 (attachment / detachment end faces) to tightly contact each other to form the optical connector 200. This allows the optical fibers 10 inserted and fixed in the opposing optical connector plugs 100 to be connected with low loss. A refractive index matching material may be applied between the sealing materials 14 to reduce return loss.

[0112] 7 , a first method for fabricating the optical connector plug of the fourth embodiment will be described. In the first fabrication method, the end face of the reference optical fiber 30 inserted and fixed in the reference connector plug 300 is positioned opposite the detachable end face 14 of the ferrule 11, and light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens the resin is irradiated from the core of the optical fiber 10 onto the photocurable resin 13, while light of the same wavelength is irradiated from the core of the reference optical fiber 30 onto the photocurable resin 13, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the detachable end face side is formed according to the position and size of the core end face of the reference optical fiber 30 on the detachable end face side of the reference connector plug 300.

[0113] Specifically, a photocurable resin 13 is filled into the hollow portion connecting the end face of the optical fiber placed in the ferrule 11 and the ferrule end face 15 (detachable end face 14). Then, a reference connector plug 300 is connected to the optical connector plug 100. The reference connector plug 300 includes a plurality of optical fibers 30, a ferrule 31, an adhesive 32, and an alignment member 36. Light sources 19 and 39 with wavelengths that increase the refractive index of the photocurable resin 13 and harden it are connected to the optical fibers 10 of the optical connector plug 100 and the optical fibers 30 of the reference connector plug 300, respectively, and light of the wavelength is irradiated onto the photocurable resin 13 from the cores 10 a and 30 a of the optical fibers 10 and 30. This increases the refractive index and hardens the irradiated portion of the photocurable resin 13, forming a waveguide 20 as shown in FIG. 8 . That is, the end face on the detachable end face side of the waveguide 20 is formed according to the position and size of the core end face of the optical fiber 30 on the detachable end face side of the reference connector plug 300. After the waveguide 20 is generated, the reference connector plug 300 and the light source 19 are removed, thereby producing the optical connector plug 100.

[0114] In this way, the end face on the detachable end face side of the waveguide 20 fabricated by the first fabrication method is formed according to the core end face of the reference connector plug 300, and therefore the end face on the detachable end face side of the waveguide 20 of an optical connector plug 100 fabricated using the same reference connector plug 300 has the same shape and size and is formed at the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 fabricated by the first fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated.

[0115] The light from the light sources 19 and 39 may have the same wavelength as the communication light to be transmitted through the optical connector, and the light may be propagated in the same propagation mode as that used for communication to generate the waveguide 20 .

[0116] 9, a cladding 21 may be formed around the waveguide 20. Specifically, after the waveguide 20 is formed, the photocurable resin 13 is removed through an injection port 22 provided in the ferrule 11, and instead a photocurable resin 13b capable of forming a cladding 21 having a lower refractive index than the waveguide 20 by light irradiation is injected. Then, a light source 37 having a wavelength that causes the photocurable resin 13b to harden is prepared, and the cladding 21 may be formed by irradiating the light source 37 with light 37a having the wavelength. The injection port 22 may be provided in advance in the ferrule 11 for removing the photocurable resin 13 and injecting the photocurable resin 13b.

[0117] A high-precision connector manufactured with a small error in the core position of the optical connector from the design target may be used as the reference connector plug 700. If an appropriate high-precision connector is not available, for example, as described in the second embodiment, a plurality of optical connectors are manufactured in which the core position is aligned by image alignment or the like so that the error from the design target is small, and from these, those with small errors are selected by end face image inspection or the like to extract three sample groups A, B, and C. The optical connectors in each sample group are connected to each other to select connector combinations that achieve lower connection loss, and the optical connector plugs of the selected optical connectors may be used as the reference connector plug 700.

[0118] 10 will be used to explain a second method for manufacturing the optical connector plug 100 according to the fourth embodiment. In the second manufacturing method, the photocurable resin 13 is irradiated with light of a wavelength that increases the refractive index of the photocurable resin 13 and hardens it from the core of the optical fiber 10, and the photocurable resin 13 is also irradiated with light of the wavelength from the attachment / detachment end face side through a photomask 42, thereby increasing the refractive index and hardening the irradiated portion of the photocurable resin 13, thereby forming the waveguide 20. The end face of the waveguide 20 on the attachment / detachment end face side is formed according to the position and size of the light transmission hole in the photomask 42.

[0119] Specifically, in the second fabrication method, instead of using the reference connector plug 300, photolithography using a photomask 42 and a light source 38 is used. The hollow portion connecting the end face of the optical fiber disposed in the ferrule 11 and the ferrule end face 15 (the detachable end face 14) is filled with photocurable resin 13. Then, a photomask 42 and a light source 38 with a wavelength that increases the refractive index of the photocurable resin 53 and hardens it are disposed near the ferrule end face 15 of the optical connector plug 100. A light source 19 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it is connected to the optical fiber 10 of the optical connector plug 100. Then, light of the wavelength is irradiated from the core 10a of the optical fiber and the photomask 42, respectively, thereby increasing the refractive index of the irradiated portion of the photocurable resin 13 and hardening it, thereby forming the waveguide 20.

[0120] The photomask 42 has light-transmitting holes corresponding to the core size at locations corresponding to the core design positions of the optical connector. The photomask 42 may have any structure as long as the light-transmitting holes allow light to pass through and the remaining portions block light. The photomask 42 may have, for example, a structure in which holes are drilled in a metal plate or a structure in which metal is vapor-deposited on the surface of a glass plate. The end face of the waveguide 20 on the detachable end face 14 side is formed according to the position and size of the light-transmitting holes in the photomask 42. After the waveguide 20 is formed, the photomask 42 and the light sources 19 and 38 are removed to produce the optical connector plug 100.

[0121] Since the end face on the detachable end face side of the waveguide 20 fabricated by the second fabrication method is formed according to the light-transmitting holes of the photomask 42, the end face on the detachable end face side of the waveguide 20 of an optical connector plug 100 fabricated using the same photomask 42 will have the same shape and size and be formed at the same position on the ferrule end face 15. Therefore, by connecting two optical connector plugs 100 fabricated by the second fabrication method, an optical connector capable of connecting optical fibers with low loss can be fabricated. Note that the cladding 21 may also be formed in the second fabrication method in the same way as in the first fabrication method.

[0122] The light sources 19 and 38 may have the same wavelength as the communication light to be transmitted through the optical connector, and the light from the light sources 19 and 38 may be propagated in the same propagation mode as that used for communication to generate the optical waveguide 20.

[0123] In this embodiment, the waveguide 20 is formed using the reference connector plug 300 or photolithography technology, but the method is not limited to these as long as it is possible to fabricate the waveguide 20 so that the core position of the optical connector plug 100 has a small error from the design target.

[0124] A method for fabricating an optical connector plug 100 for connecting a multicore fiber will be described with reference to Fig. 11. Here, as an example, a method for fabricating the optical connector plug 100 using the first fabrication method described above will be described. A reference connector plug 300 is connected to the optical connector plug 100.

[0125] The optical fiber 10 of the optical connector plug 100 and the optical fiber 30 of the reference connector plug 300 are each connected to a single-core fiber 40 via a fan-out 41. Light sources 19, 39 with a wavelength that increases the refractive index of the photocurable resin 13 and hardens it are connected to each single-core fiber 40, and light of the wavelength is irradiated onto the photocurable resin 13 from the cores 10a, 30a of the optical fibers 10, 30.

[0126] This causes an increase in the refractive index and hardening of the photocurable resin 13 in the irradiated portions, forming a plurality of waveguides 20 as shown in FIG. 12 . After the waveguides 20 are formed, the reference connector plug 300 and the fan-out 41 are removed to produce the optical connector plug 100. By connecting two optical connector plugs 100 produced using the same reference connector plug 300, it is possible to produce an optical connector capable of connecting optical fibers with low loss. Although FIGS. 11 and 12 show an example of a multicore fiber having four cores, the number of cores in the multicore fiber may be two or more, and the core arrangement may be any desired arrangement.

[0127] The optical connectors of the first to fourth embodiments described above have a waveguide formed using a photocurable resin, one end of which is connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and which is capable of transmitting an optical signal from the core of the optical fiber to the other end, and the end face of the other end is formed in accordance with the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug for waveguide fabrication.

[0128] The optical connectors of the first to fourth embodiments have a waveguide formed using a photocurable resin, one end of which is connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, and which is capable of transmitting an optical signal from the optical fiber core to the other end, and the end face of the other end of the waveguide is formed according to the position and size of the light-transmitting hole in a photomask used to fabricate the waveguide.

[0129] In a first method for producing (manufacturing) an optical connector plug used in the optical connectors of the first to fourth embodiments, the optical connector plug includes a ferrule capable of holding a connection end of an optical fiber and photocurable resin, the connection end of the optical fiber inserted and fixed in the ferrule, the photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber, and a sealant that forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out. An end face of a reference optical fiber inserted and fixed in a reference connector plug is arranged opposite the detachable end face of the ferrule, and light of a wavelength that increases the refractive index of the photocurable resin and hardens the photocurable resin is irradiated from the core of the optical fiber onto the photocurable resin, and light of the same wavelength is irradiated from the core of the reference optical fiber onto the photocurable resin, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening the resin, thereby forming a waveguide, and the end face of the waveguide on the detachable end face side is formed in accordance with the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug.

[0130] In a second method for producing (manufacturing) an optical connector plug used in the optical connectors of the first to fourth embodiments, the optical connector plug has a ferrule capable of holding a connection end of an optical fiber and photocurable resin, the connection end of the optical fiber inserted and fixed into the ferrule, the photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber, and a sealant that forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out, and the photocurable resin is irradiated from the core of the optical fiber with light of a wavelength that increases the refractive index of the photocurable resin and hardens, and the photocurable resin is irradiated from the detachable end face side with light of the same wavelength through a photomask, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening it, thereby forming a waveguide, and the end face of the waveguide on the detachable end face side is formed according to the position and size of the light-transmitting hole of the photomask.

[0131] As a result, in this embodiment, an optical connector capable of connecting single-mode and multi-mode optical fibers with low loss can be provided, and an optical connector plug for the optical connector can be easily manufactured.

[0132] Specifically, a low-loss optical connector can be provided by combining optical connector plugs 100 in which waveguides are formed using the same reference connector or the same photomask to create an optical connector. Furthermore, according to this embodiment, an optical connector plug for an optical connector that does not require precise core alignment can be easily produced.

[0133] The present disclosure is not limited to the above-described embodiments, and various modifications and combinations are possible.

[0134] 10, 30, 50, 70 Optical fiber 10a, 30a, 50a, 70a Core 10b, 30b, 50b, 70b Cladding 100, 500 Optical connector plug 11, 31, 51, 71 Ferrule 12, 32 Adhesive 13, 13b, 53 Photocurable resin 14, 54 Sealing material (detachable end face) 15, 55 Ferrule end face 16, 36 Alignment member 18 Refractive index matching material 19, 37, 38, 39, 69, 88, 89 Light source 20, 60 Waveguide (self-written optical waveguide) 200, 600 Optical connector 21 Cladding 22 Inlet 300, 700 Reference connector plug 37a 38a, 88a Light 40, 80 Single-core fiber 41, 61 Fan-out 42, 62 Photomask 52, 72 Plug frame 56, 76 Knob 57, 77 Flange 58, 78 Spring 59, 79 Stop ring 63 Sleeve

Claims

1. An optical connector having a waveguide formed using a photocurable resin, one end of the waveguide being connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, capable of transmitting an optical signal from the core of the optical fiber to the other end, the end face of the other end of the waveguide being formed in accordance with the position and size of the core end face of a reference optical fiber on the detachable end face side of a reference connector plug for fabricating a waveguide.

2. An optical connector having a waveguide formed using a photocurable resin, one end of the waveguide being connected to the core end face of an optical fiber inserted and fixed in an optical connector plug, capable of transmitting an optical signal from the optical fiber core to the other end, the end face of the other end of the waveguide being formed according to the position and size of a light-transmitting hole in a photomask used to fabricate the waveguide.

3. The optical connector according to claim 1 or 2, wherein the optical connector plug comprises: a ferrule capable of holding the connection end of the optical fiber and the photocurable resin; and a sealing material that forms the detachable end face of the ferrule and prevents the outflow of the photocurable resin.

4. A method for manufacturing an optical connector plug for use in an optical connector, wherein the optical connector plug has: a ferrule capable of holding a connection end of an optical fiber and photocurable resin; the connection end of the optical fiber inserted and fixed in the ferrule; photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber; and a sealant which forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out; an end face of a reference optical fiber inserted and fixed in a reference connector plug is arranged opposite the detachable end face of the ferrule; the photocurable resin is irradiated from the core of the optical fiber with light of a wavelength which increases the refractive index of the photocurable resin and hardens, and the photocurable resin is irradiated with light of the same wavelength from the core of the reference optical fiber, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening it, thereby forming a waveguide; and the end face of the waveguide on the detachable end face side is shaped in accordance with the position and size of the core end face of the reference optical fiber on the detachable end face side of the reference connector plug.

5. A method for manufacturing an optical connector plug for use in an optical connector, the optical connector plug having: a ferrule capable of holding a connection end of an optical fiber and photocurable resin; the connection end of the optical fiber inserted and fixed within the ferrule; photocurable resin filled in the ferrule so as to abut against the connection end of the optical fiber; and a sealant that forms a detachable end face of the ferrule and prevents the photocurable resin from leaking out, wherein the photocurable resin is irradiated from the core of the optical fiber with light of a wavelength that increases the refractive index of the photocurable resin and hardens, and the photocurable resin is irradiated from the detachable end face side with light of the wavelength through a photomask, thereby increasing the refractive index of the irradiated portion of the photocurable resin and hardening it, thereby forming a waveguide, and the end face of the waveguide on the detachable end face side is shaped in accordance with the position and size of the light-transmitting hole of the photomask.

6. A method for manufacturing an optical connector plug according to claim 4 or 5, wherein, after forming the waveguide, the photocurable resin is removed from the portion where the waveguide is not formed, another photocurable resin capable of forming a cladding having a lower refractive index than the waveguide is filled into the ferrule, and light of a wavelength that causes the other photocurable resin to harden is irradiated from the detachable end face side, thereby hardening the other photocurable resin and forming the cladding around the waveguide.

7. A method for manufacturing an optical connector plug as described in claim 4, wherein the light irradiated from the core of the optical fiber and the light irradiated from the core of the reference optical fiber have the same wavelength and propagation mode as the communication light to be transmitted through the optical connector.

8. A method for manufacturing an optical connector plug according to claim 5, wherein the light irradiated from the core of the optical fiber and the light irradiated through the photomask have the same wavelength and propagation mode as the communication light to be transmitted through the optical connector.

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