JP6122784B2 - Optical fiber side input / output device and optical communication switching system - Google Patents

Description

  The present invention relates to a technique for inputting and outputting light from the side of an optical fiber.

  Optical fiber side input / output technology enables the transmission and reception of optical signals between two optical fibers by a structure in which another optical fiber is abutted against the side of a bent portion of an optical fiber bent at an angle. Technology. Hereinafter, in this specification, the optical fiber that is bent is referred to as a bent optical fiber, and the optical fiber that is abutted against the side surface of the bent optical fiber is referred to as a probe fiber. Application of the optical fiber side input / output technology to a leakage light monitor, test light incidence for controlling a core wire, or a short interruption switch for changing the route of an optical line is being studied.

  FIG. 17 is a conceptual diagram for explaining an optical fiber side input / output device. A coated optical fiber or the like is pressed against the cylindrical portion 2 which is a cylindrical rigid body, and the bent optical fiber 1 is formed. The refractive index matching agent 4 which is a transparent gel-like member is formed so as to have a certain thickness so as to cover the bent portion 3 which is in close contact with the cylindrical portion 2. The end face of the probe fiber 5 is abutted against the bent portion 3 so as to be inserted into the refractive index matching agent 4, thereby forming a lateral input / output optical system. A lens (not shown) may be formed on the end face of the probe fiber 5.

  The radius of curvature of the portion of the bent portion 3 that contacts the cylindrical portion 2 is, for example, 1.7 mm, and the angle formed by the arc portion is about 30 degrees. By forming the bent portion 3, the total reflection condition of the optical fiber is relaxed, and light can be input / output from the side of the optical fiber. Light from the bent optical fiber 1 passes through the refractive index matching agent 4 and enters the probe fiber 5 and is output to the outside. The traveling direction of the light is reversible, and the light from the probe fiber 5 can be input to the bent optical fiber 1 through the same path.

  For example, a short break switch has been proposed as a usage application of this technology. The short interruption switch can be applied to an optical communication line switching device in an access network, for example. The optical communication line switching device is a device for bypassing an optical signal to a detour line by optical fiber side input / output technology. If this type of device is used, communication can be maintained on the detour line even if the working optical fiber is cut off due to troubled relocation work, etc., so the switching work of the optical communication line can be performed in-service.

  FIG. 18 is a diagram illustrating an optical communication line switching device disclosed in Patent Document 2. An optical communication line switching device is formed by providing a pair of side light input / output mechanisms in the middle of the working optical line optical fiber to divert the light. Further, as shown in FIG. 19, a pair of optical communication line switching devices are arranged opposite to each other on the working optical line optical fiber, and the new optical line optical fiber 300 ′ is connected in parallel with the working optical line optical fiber, so that It is possible to form an optical system capable of switching the path from the working optical line optical fiber to the new optical line optical fiber 300 ′ with a short interruption.

JP 2009-25210 A JP 2012-252099 A

Tanaka, Araki, Higashi, "Individual test of PON branch line by local injection", 2008 IEICE General Conference B-10-5, Proceedings of Communication Lecture 2, PP288, 2008-3 Honda, Iwata, Shinho, Kawano, Manabe, Higashi, “Study on optical fiber breakage in small-diameter bending test”, 2012 IEICE Communication Society B-10-23, Communication Lectures Collection 2, P205 Honda, Kawano, Iwata, Maho, Manabe, Higashi, “Basic study of optical line switching method using local optical input / output”, IEICE Technical Report: IEICE 112 ( 261), 43-46, 2012-10-25 Maho Makoto, Enobu Hamada, Natsuki Honda, Tomohiro Kawano, Tetsuya Manabe, Yuji Higashi, “Basic study on the input section of a cardiac contrast device using local optical input technology”, IEICE Technical Report, OFICE2012-54 (2013-01) Enobu Hamada, Tomohiro Kawano, Makoto Maho, Kazutaka Nodo, Natsuki Honda, Tetsuya Manabe, “Examination of core-line contrast transmitter using lateral light input technology”, IEICE Technical Report, IEICE Technical Report, OFT2012-79, OPE2012-197 (2013-03) Enobu Hamada et al., “Design examination of test light incidence mechanism using optical fiber lateral input technology”, OFT 2011-84, pp. 57-60, 2012

  In the optical fiber side input / output device, the efficiency when the leaked light recombines with the probe fiber, that is, the optical coupling efficiency is important. If the optical coupling efficiency is low, the optical signal is lost, resulting in many problems such as deterioration of the S / N ratio. In the existing technology, the opening angle of the probe fiber that receives the leaked light is narrow, and the loss of light collected on the probe fiber core (core diameter: φ10 μm) is large. For this reason, it is difficult to reliably capture the optical signal (leakage light), and the improvement of the optical coupling efficiency reaches its peak. In particular, in application to a short break switch or the like, there is a problem that sufficient optical coupling efficiency cannot be obtained between the existing fiber and the probe fiber.

  The present invention has been made paying attention to the above circumstances, and an object thereof is to provide an optical fiber side input / output device and an optical communication switching system capable of reliably capturing leaked light.

  In order to achieve the above object, the present invention has the following aspects.

(1) An optical fiber side input / output device according to the present invention is an optical fiber side input / output device that inputs / outputs light to / from an optical fiber formed with a bent portion. This optical fiber side input / output device is provided between the bending portion and the end surface, and an optical fiber for incidence that can face incident light to the bending portion through the end surface. The optical system which changes the path | route of the leakage light which leaks from a part in the direction which goes to the said end surface from a bending part, and the capture | acquisition part which capture | acquires the leakage light from which the path | route was changed.

  That is, according to the aspect (1), the path of the leaked light is bent in a direction different from the incident optical fiber as the probe fiber, and the leaked light is captured by the capturing unit. This makes it possible to reliably capture leaked light regardless of the limitations associated with the incident optical fiber.

  (2) In the optical fiber side input / output device according to the present invention, the capturing unit in (1) includes a light receiving element that receives the leaked light whose path has been changed. Thereby, the leakage light can be optically / electrically converted without loss.

  (3) In the optical fiber side input / output device according to the present invention, the capturing unit in (1) includes a multimode optical fiber having a core diameter capable of receiving leaked light whose path has been changed. Thereby, leaked light can be captured without loss.

(4) In the optical fiber side input / output device according to the present invention, the optical system in (1) includes a mirror portion that reflects leaked light in a direction different from the direction from the bent portion of the incident optical fiber toward the end surface. . As a result, the path of the leaked light is changed without loss.

  (5) In the optical fiber side input / output device according to the present invention, the optical system in (4) includes a light-transmissive solid member that presses the optical fiber against a curved surface to form a bent portion, and a mirror portion. Is formed into a film on the solid member. This improves the manufacturing yield.

  (6) An optical communication switching system according to the present invention temporarily bypasses an optical signal exchanged between a first device and a second device connected via a first optical fiber to the second optical fiber. This is an optical communication switching system. In this optical communication switching system, a bent portion is formed in the first optical fiber by the optical fiber side input / output device according to any one of claims (1) to (5). An optical coupling unit that optically couples the first optical fiber and the second optical fiber, and the second optical fiber is connected to the incident optical fiber of the optical fiber side input / output device, and the second optical fiber A first optical signal transmitted from the first apparatus to the second apparatus via the first optical signal via the incident optical fiber and incident on the bending portion and transmitted to the second apparatus; and a second apparatus The second optical signal that is uplink-transmitted from the first to the first device is leaked from the bent portion, captured by the capturing unit of the optical fiber side input / output device, and transmitted to the first device via the second optical fiber. A link optical transmission system.

  That is, according to the aspect (6), it is possible to reliably capture the second optical signal transmitted in the uplink, and to perform the switching work without loss.

  (7) In (6), the optical communication switching system according to the present invention further includes a relay amplifier that amplifies the captured second optical signal. By doing so, the second optical signal transmitted in the uplink is amplified, and the loss can be further reduced.

  (8) An optical communication switching system according to the present invention temporarily bypasses an optical signal exchanged between a first device and a second device connected via a first optical fiber to the second optical fiber. This is an optical communication switching system. The optical communication switching system includes a first closure that houses the first optical fiber and the second optical fiber on the first device side, and a second closure that houses the first optical fiber and the second optical fiber on the second device side. It comprises.

  The first closure includes a first optical input / output device that uses the optical fiber side input / output device of any one of (1) to (5), and forms a bent portion in the first optical fiber; The first optical signal transmitted through the downlink to the apparatus leaks from the bent portion of the first optical input / output device, is captured by the capturing unit of the first optical input / output device, and is transmitted through the second optical fiber to the second device. The first optical signal transmitted to the first device and transmitted from the second device to the first device through the incident optical fiber of the first optical input / output device to the bending portion and transmitted to the first device. A transmission system.

  The second closure forms a bent portion in the first optical fiber, uses the optical fiber side input / output device of any one of (1) to (5), and the second optical signal to the second optical signal. Leakage from the bending portion of the two optical input / output device, capture by the capturing portion of the second optical input / output device, and transmission to the first device via the second optical fiber, and the first optical signal to the second optical input / output device A second optical transmission system that is incident on the bending portion from the incident optical fiber and is transmitted to the second device.

  That is, according to the aspect (8), since the first optical transmission system is formed in the first closure and the second optical transmission system is formed in the second closure, the switching work can be easily performed.

  That is, according to the present invention, it is possible to provide an optical fiber side input / output device and an optical communication switching system that can reliably capture leaked light.

FIG. 1 is a diagram illustrating an example of an optical communication switching system to which an optical fiber side input / output device according to an embodiment can be applied. FIG. 2 is a block diagram illustrating an example of an optical fiber side input / output device according to the first embodiment. FIG. 3 is a diagram showing the reflection characteristics of the wavelength beam splitter 6 shown in FIG. FIG. 4 is a diagram illustrating another example of the optical communication switching system to which the optical fiber side input / output device according to the embodiment can be applied. FIG. 5 is a block diagram illustrating an example of an optical fiber side input / output device according to the second embodiment. FIG. 6 is a block diagram illustrating an example of an optical fiber side input / output device according to the third embodiment. FIG. 7 is a block diagram illustrating an example of an optical fiber side input / output device according to the fourth embodiment. FIG. 8 is a diagram showing the reflection characteristics of the wavelength beam splitter 6 shown in FIG. FIG. 9 is a block diagram illustrating an example of an optical fiber side input / output device according to the fifth embodiment. FIG. 10 is a diagram showing various shapes of the wavelength beam splitter 6. FIG. 11 is a diagram illustrating another example of an optical communication switching system to which the optical fiber side input / output device according to the embodiment can be applied. FIG. 12 is a diagram illustrating another example of an optical communication switching system to which the optical fiber side input / output device according to the embodiment can be applied. FIG. 13 is a block diagram illustrating an example of an optical fiber side input / output device according to the ninth embodiment. FIG. 14 is a block diagram illustrating another example of the optical fiber side input / output device according to the ninth embodiment. FIG. 15 is a block diagram illustrating an example of an optical fiber side input / output device according to the tenth embodiment. FIG. 16 is a block diagram illustrating another example of the optical fiber side input / output device according to the tenth embodiment. FIG. 17 is a conceptual diagram for explaining an optical fiber side input / output device. FIG. 18 is a diagram showing a short break switch shown in Patent Document 2. As shown in FIG. FIG. 19 is a diagram illustrating an optical communication line switching device disclosed in Patent Document 2.

[First Embodiment]
FIG. 1 is a diagram illustrating an example of an optical communication switching system to which an optical fiber side input / output device according to an embodiment can be applied. This system includes a station-side transmission device 20 installed in a telephone station or the like, and a subscriber-side transmission device 30 installed in a subscriber's house or the like. The station-side transmission device 20 and the subscriber-side transmission device 30 are interconnected via an optical fiber 40s and exchange optical signals with each other.

  In the embodiment, light having a wavelength of 1550 nm (referred to as long wavelength light in the embodiment), light having a wavelength of 1490 nm (referred to as medium wavelength light in the embodiment), and light having a wavelength of 1310 nm (referred to as short wavelength light in the embodiment). Think. Among them, long wavelength light and medium wavelength light are transmitted from the station side transmission device 20 to the subscriber side transmission device 30 in the downlink. The short wavelength light is transmitted from the subscriber side transmission device 30 to the station side transmission device 20 via the uplink. The distinction between long, medium, and short here is only for comparison and is not an absolute indicator.

  Communication from the station-side transmission device 20 to the subscriber-side transmission device 30 is provided by medium wavelength light. Communication from the subscriber-side transmission device 30 to the station-side transmission device 20 is provided by short wavelength light. Long wavelength light provides television broadcast services to subscribers, for example.

  In FIG. 1, an active optical fiber 40s used for in-service is connected to an in-house coupler 50 on the inside and branched to a bypass optical fiber 40p. The in-house coupler 50 optically couples the optical fiber 40s and the optical fiber 40p. The optical fiber 40s and the optical fiber 40p are drawn into the optical network unit (ONU) side closure 60 on the outside.

  The optical fiber 40 s accommodated in the ONU side closure 60 is connected to the subscriber side transmission device 30 via the temporary light blocking mechanism 61 and the optical fiber side input / output device 67. The optical fiber side input / output device 67 forms a bent portion in the optical fiber 40s.

  The optical fiber 40 p accommodated in the ONU side closure 60 is connected to a WDM (Wavelength Division Multiplex) coupler 64 via a temporary light blocking mechanism 62. The WDM coupler 64 connects the long wavelength light from the optical fiber 40 p to the optical amplifier 65 and connects the medium wavelength light to the relay amplifier 71.

  The long wavelength light amplified by the optical amplifier 65 and the medium wavelength light amplified by the relay amplifier 71 are combined by another WDM coupler 66, and both are incident on the optical fiber side input / output device 67. The optical fiber side input / output device 67 causes the long wavelength light and the medium wavelength light to enter the optical fiber 40 s from the bent portion, and allows the wavelength light to reach the subscriber side transmission device 30.

  With the above configuration, a downlink optical transmission system is formed. The downlink optical transmission system connects the optical fiber 40 p to the probe fiber of the optical fiber side input / output device 67. Then, long-wavelength light and medium-wavelength light transmitted through the optical fiber 40p through the optical fiber 40p are incident on the bending portion from the probe fiber and transmitted to the subscriber-side transmission device 30. The probe fiber will be described with reference to FIG.

  Short-wavelength light that is uplink-transmitted from the subscriber-side transmission device 30 toward the station-side transmission device 20 leaks from the bent portion of the optical fiber 40 s and is avalanche photodiode (APD) 68 of the optical fiber side input / output device 67. Be captured. The captured short wavelength light is converted into an electrical signal and input to the relay amplifier 69.

  The relay amplifier 69 amplifies the electric signal from the APD 68 and then returns it to an optical signal by a semiconductor laser (not shown). This optical signal enters the WDM coupler 66, reaches the WDM coupler 64 via the relay amplifier 71, and is coupled to the optical fiber 40p. The optical fiber 40p goes out of the ONU side closure 60 through the temporary light blocking mechanism 62 and is extended to the in-house coupler 50 inside.

  With the above configuration, an uplink optical transmission system is formed. The uplink optical transmission system leaks short-wavelength light from the bent portion, captures it by the APD 68, and transmits it to the station-side transmission device 20 via the optical fiber 40p. The temporary light blocking mechanisms 61 and 62 in the ONU side closure 60 operate in synchronization with each other under the control of the synchronous operation control unit 63.

  FIG. 2 is a block diagram illustrating an example of an optical fiber side input / output device according to the first embodiment. Optical fiber side input / output device The optical fiber side input / output device 67 shown in FIG. 1 can be applied.

  The optical fiber side input / output device shown in FIG. 2 includes a cylindrical portion 2, a probe fiber 5, and a photodiode 8. The photodiode 8 is sealed in a TO-can (Top Open Can) 7 and receives light from an opening formed in the TO-can 7 with high efficiency.

  The optical fiber is pressed against the cylindrical portion 2 to form a bent portion 3 having a certain curvature along the shape of the cylindrical portion 2. The optical fiber in which the bent portion 3 is formed is referred to as a bent optical fiber 1. Light can be input to and output from the bending optical fiber 1 through the bending portion 3.

The probe fiber 5 is arranged so that its end face is abutted against the bending portion 3. Incident light from the probe fiber 5 is radiated from the end face and can enter the bent optical fiber 1 from the bent portion 3. By bringing the gel-like refractive index matching agent 4 into contact with the bending portion 3 and inserting the probe fiber 5 into the refractive index matching agent 4, an optical system as shown in FIG. 2 can be formed. As the refractive index matching agent 4, a material close to the refractive index of the coating of the bent optical fiber 1 is preferably selected.

By the way, in the first embodiment, a multilayered wavelength beam splitter 6 is provided between the bent portion 3 and the end face of the probe fiber 5, for example. The wavelength beam splitter 6 is installed obliquely with respect to the traveling direction of the leaked light leaking from the bent portion 3, and changes the path of the leaked light in a direction different from the direction toward the end face of the probe fiber 5. That is, the wavelength beam splitter 6 transmits incident light radiated from the end face to reach the bent portion 3, but reflects the leaked light from the bent portion 3 and irradiates the photodiode 8. The wavelength beam splitter 6 has a function as a mirror part that reflects light in a specific wavelength band in the leaked light toward the photodiode 8.

  The photodiode 8 captures the leaked light that has been rerouted (reflected) by the wavelength beam splitter 6 and converts it into an electrical signal. This electric signal can be amplified by, for example, an amplifier (not shown) and then returned to an optical signal by a semiconductor laser (not shown). That is, the photodiode 8 corresponds to the APD 68 shown in FIG.

  FIG. 3 is a diagram showing the reflection characteristics of the wavelength beam splitter 6 shown in FIG. In the first embodiment, the wavelength beam splitter 6 is configured to reflect light in a short wavelength region (near 1310 nm) and transmit light in a medium wavelength region and a long wavelength region (1490 nm or more). As a result, in FIG. 1, medium wavelength light and long wavelength light from the WDM coupler 66 are incident on the optical fiber 40 s and transmitted to the subscriber side transmission device 30, and short wavelength light from the subscriber side transmission device 30 is transmitted to the APD 68. Incident light can be input to the relay amplifier 69.

  In the existing optical fiber side input / output device, the leakage light is incident on the probe fiber to capture the leakage light. However, due to the small cross-section of the probe fiber and the small amount of received light and the limited optical coupling efficiency, it has been difficult to reliably capture leaked light without loss. In the first place, since the intensity of leaked light is very weak, there is a loss even if a fiber with a lens is used as a probe fiber.

  On the other hand, in the optical fiber side input / output device (FIG. 2) according to the first embodiment, the path of the leaked light is changed by the wavelength beam splitter 6, and the leaked light is actively prohibited from entering the probe fiber. To do. The light receiving surface of the photodiode 8 is arranged on the changed path of the leaked light so that the leaked light can be received with high efficiency.

  As can be easily understood, the light receiving surface of the photodiode 8 is so wide that it cannot be compared with the cross section of the probe fiber, so that the amount of received light can be increased by an order of magnitude. Incidentally, since the diameter of a normal photodiode is about 50 μm, it is possible to reliably capture leaked light.

  In addition, under the configuration shown in FIG. 2, the tolerance of alignment between the leaked light and the photodiode 8 is much larger than that of the structure in which the leaked light is received by the probe fiber. Therefore, the labor of alignment can be reduced, and the manufacturing time of the apparatus can be shortened to promote cost reduction. From these facts, according to the first embodiment, it is possible to provide an optical fiber side input / output device capable of reliably capturing leaked light.

  It goes without saying that the optical loss in the optical fiber switching work can be reduced by using the optical fiber side input / output device as described in the first embodiment. Returning to FIG. 1, the procedure of optical fiber switching work in the optical communication switching system according to the embodiment will be described.

  In a normal state, the light temporary blocking mechanism 61 in the ONU side closure 60 is opened, and the light temporary blocking mechanism 62 is closed. Thereby, long wavelength light, medium wavelength light, and short wavelength light can be transmitted and received via the optical fiber 40s. The optical fiber 40s has a bent portion formed by the optical fiber side input / output device 67 and causes a loss of about -2 dB, which is within an allowable range.

  In order to replace a part of the current optical fiber 40s with a new optical fiber, an optical fiber switching work is performed. Immediately before cutting the working optical fiber 40s, the temporary light blocking mechanism 61 is closed and the temporary light blocking mechanism 62 is opened. This switching is performed simultaneously by the synchronous operation control unit 63. As a result, the paths of the long wavelength light, medium wavelength light, and short wavelength light are switched to the bypass optical fiber 40p without interruption. When the replacement with the new optical fiber is completed, the optical signal path is switched back to the optical fiber 40s.

  By using the optical fiber side input / output device 67 according to the first embodiment, uplink short wavelength light (1310 nm) can be bypassed to the optical fiber 40p without loss. Therefore, not only signal acquisition can be performed accurately, but also the signal delivery to the detour is made efficient, and even weak signals can be relayed accurately. From these facts, according to the first embodiment, it is possible to provide an optical communication switching system capable of reliably capturing leaked light and performing switching work while maintaining communication quality.

[Second Embodiment]
FIG. 4 is a diagram illustrating another example of the optical communication switching system to which the optical fiber side input / output device according to the embodiment can be applied. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and only different parts will be described here. In the optical communication switching system of FIG. 4, the TO-can 7 and the photodiode 8 in the optical fiber side input / output device 67 are replaced with a large core diameter multimode fiber 9.

  FIG. 5 is a block diagram illustrating an example of an optical fiber side input / output device according to the second embodiment. The short wavelength light reflected by the wavelength beam splitter 6 is captured by the large core diameter multimode fiber 9. Since the large-core-diameter multimode fiber 9 can receive a large amount of light, the same effect as in the first embodiment can be obtained.

[Third Embodiment]
FIG. 6 is a block diagram illustrating an example of an optical fiber side input / output device according to the second embodiment. The optical fiber side input / output device of FIG. 6 includes a prism beam splitter 10 instead of the refractive index matching agent 4 in the optical fiber side input / output device of FIG. The wavelength beam splitter 6 is formed in a film shape inside the prism beam splitter 10.

The prism beam splitter 10 is formed of a light transmissive solid member such as glass or acrylic. The prism beam splitter 10 presses the bending optical fiber 1 against the curved surface of the cylindrical portion 2 to form the bending portion 3. Furthermore, the prism beam splitter 10 includes a first plane that is substantially in close contact with the end face of the probe fiber 5 and a second plane that is substantially perpendicular to the first plane and is in contact with the TO-can 7. A pressure may be applied to enhance the mutual adhesion between the prism beam splitter 10 and the bent optical fiber 1, the probe fiber 5, and the TO-can 7.

  In the above configuration, since all the light passes through the transparent solid, the refractive index matching agent can be dispensed with. Thereby, since the consumption of the refractive index matching agent which is a fluid (gel) is eliminated, an effect that the optical path is stabilized without fluctuation is obtained.

[Fourth Embodiment]
FIG. 7 is a block diagram illustrating an example of an optical fiber side input / output device according to the fourth embodiment. In FIG. 7, the reflection characteristics of the wavelength beam splitter 6 are different from those in FIG. 2, and medium wavelength light is incident on the photodiode 8.

  FIG. 8 is a diagram showing the wavelength dependency of the reflectance of the wavelength beam splitter 6 of the optical fiber side input / output device shown in FIG. As shown in FIG. 8, the wavelength beam splitter 6 has a bandpass characteristic that reflects light in the band near 1490 nm, so that medium wavelength light is reflected and incident on the photodiode 8.

  In the first embodiment, an example in which short-wavelength light (1310 nm) transmitted from the subscriber side transmission apparatus 30 in uplink is selected and amplified and relayed is shown. In the fourth embodiment, medium wavelength light (1490 nm) transmitted in downlink from the station-side transmission device 20 is selected and amplified and relayed. Thus, by changing the reflectance characteristic of the wavelength beam splitter 6, the degree of freedom in designing the optical communication switching system can be increased.

[Fifth Embodiment]
FIG. 9 is a block diagram illustrating an example of an optical fiber side input / output device according to the fifth embodiment. In the configuration of FIG. 9, the TO-can 7 and the photodiode 8 in the configuration of FIG. 7 are replaced with a large core diameter multimode fiber 9. According to this configuration, in addition to the effects obtained by the fourth embodiment, an optical fiber side input / output device and an optical communication switching system that have the same effects as those of the second embodiment can be realized.

[Sixth Embodiment]
As shown by the thick line in FIG. 10, the wavelength beam splitter 6 can be formed in various shapes. A planar thin film as shown in (a) is typical. Alternatively, it may be formed on the sandwiching surface of a right-angled triangle shown in (b) and (c) or a cubic prism bonded with a right-angled triangle prism as shown in (d). Further, it may be formed on a trapezoidal hypotenuse as shown in (f) and (g), or may be formed on a thick plate. (E) corresponds to the mode shown in FIG. 6 and may be formed at an interface sandwiched between prisms having a curved surface and a flat surface. When the refractive index matching agent is formed around the prism, the refractive indexes are close to each other, so that it can be handled as if only the film of the beam splitter exists.

[Seventh Embodiment]
FIG. 11 is a diagram illustrating another example of an optical communication switching system to which the optical fiber side input / output device according to the embodiment can be applied. The difference from the configuration shown in FIG. 1 or FIG. 4 is that the optical amplifier and the relay amplifier of the ONU side closure 60 are moved to the inside. A reference numeral 82 is given to the optical amplifier inside, and a reference numeral 84 is given to the relay amplifier.

  According to the configuration shown in FIG. 11, it is possible for the operator of the switching work to perform the work without bringing the optical amplifier and the relay amplifier to the construction site, so that labor is greatly reduced. In addition, when a plurality of switching works occur continuously for the same station, the optical amplifier and the relay amplifier can be shared by the respective works, so that there is an advantage that the cost can be reduced.

[Eighth Embodiment]
FIG. 12 is a diagram illustrating another example of an optical communication switching system to which the optical fiber side input / output device according to the embodiment can be applied. In the optical communication switching system according to the eighth embodiment, an optical line terminal (OLT) side closure 90 is provided in the vicinity of the station side transmission apparatus 20, and both the ONU side closure 60 and the OLT side closure 90 on the subscriber side are used. The optical fibers 40s and 40p are accommodated. The optical arrangement of the second embodiment is arranged in the ONU side closure 60, and the optical arrangement of the fifth embodiment is arranged in the OLT side closure 90.

  With the above configuration, the in-house coupler 50 can be eliminated, and it is not necessary to dispose the detour path (optical fiber 40p) from the in-house coupler 50 to the subscriber side. In reality, there are many cases where there is no empty core wire (core wire) suitable for the optical fiber 40p. According to the configuration shown in FIG. 12, it is possible to switch an optical fiber between arbitrary closures even when there is no free core wire (core wire) to the station-side transmission device 20.

  As described above, the optical fiber side input / output device 67 according to the embodiment is disposed in both the OLT side closure 90 and the ONU side closure 60 on the optical fiber 40s, so that the switching work is performed in an arbitrary section. It becomes possible to do. Of course, the same effect can be obtained by using the optical arrangement according to another embodiment.

[Ninth Embodiment]
In the optical fiber side input / output devices described in the first to eighth embodiments, the wavelength beam splitter 6 serving as a mirror portion has a semi-reflective characteristic. The semi-reflective property referred to here is a property of transmitting light of a specific wavelength and reflecting part of the light.
In the ninth embodiment, a reflecting mirror 200 having total reflection characteristics is used in place of the wavelength beam splitter 6. The total reflection characteristic is a characteristic of reflecting light in all wavelength bands. The reflecting mirror 200 has a function as a mirror part that reflects leaked light in a specific direction over the entire wavelength band.

  FIG. 13 is a block diagram illustrating an example of an optical fiber side input / output device according to the ninth embodiment. In FIG. 13, the bending optical fiber 1 is pressed against the cylindrical portion 2 by the glass block 11 and is gripped in a state where the bending portion 3 is generated. The glass block 11 has a surface formed obliquely with respect to the leakage light irradiation path, and a reflective film 200 is formed on the surface by, for example, depositing a multilayer film. The form of the reflecting mirror 200 is not limited to a plane mirror, and may be a concave mirror, for example.

  The leaked light from the bending part 3 passes through the glass block 11 and is irradiated on the reflecting mirror 200. The reflecting mirror 200 totally reflects the leaked light and enters the probe 12. The probe 12 is installed at a position where the leaked light can be captured with the maximum optical coupling efficiency. The probe 12 is connected to an optical system (not shown) that reaches, for example, a photodiode or an optical amplifier.

  As shown in FIG. 17, the existing optical fiber side input / output device has a structure in which the leaked light from the bending portion 3 goes straight and is captured by the probe fiber 5 on the path. For this reason, in order to prevent interference between the probe 12 and the bent optical fiber 1, there is no choice but to limit the size, installation direction, installation location, etc. of the probe 12. Therefore, it is difficult to install the probe 12 under the optimum conditions, resulting in a decrease in optical coupling efficiency and downsizing of the apparatus.

  On the other hand, according to the configuration shown in FIG. 13, the leakage light can be collected at an arbitrary position by the reflecting mirror 200, so that restrictions on the size and position of the probe 12 can be relaxed. . As a result, the optical coupling efficiency can be increased, and the apparatus can be reduced in size. Of course, since the traveling direction of the light is reversible, the communication light or the test light can be incident on the bent optical fiber 1 from the probe 12 as in the existing apparatus.

  When the bending angle of the bent optical fiber 1 is made shallow for miniaturization, the leaked light is leaked at a position near the bent optical fiber 1. By using the reflecting mirror 200, interference between the probe 12 and the bent optical fiber 1 can be avoided, so that the probe 12 can be installed at an optimum position.

  FIG. 14 shows an optical fiber side input / output device in which the probe 12 shown in FIG. The photodiode 8 is installed at a position where the optical coupling efficiency with the leaked light is maximized. Since the leaked light is collected at an arbitrary position by the reflecting mirror 200, it is possible to install the photodiode 8 without any size or position restrictions. As a result, the optical axis adjustment of the leaked light can be reduced. Further, since the photodiode 8 directly receives the leakage light, the number of parts can be reduced.

  According to the ninth embodiment, the restriction on the installation conditions of the probe 12 can be relaxed, so that the bending optical fiber 1 can be deformed with an optimal bending radius and bending angle to increase the output level of leaked light. Further, as shown in FIGS. 13 and 14, since the probe 12 is not directly abutted against the bent optical fiber 1, a mechanical collision can be avoided, and as a result, reliability can be improved. .

[Tenth embodiment]
FIG. 15 is a diagram illustrating an example of an optical fiber side-in / out device according to the tenth embodiment. In FIG. 15, the bending optical fiber 1 is pressed against the cylindrical portion 2 by the bending pressing portion 14 and is gripped in a state where the bending portion 3 is generated. One surface of the glass block 13 is disposed obliquely with respect to the path of the leaked light from the bent portion 3. And the reflective mirror 200 is formed by vapor-depositing, for example, a multilayer film on this surface. Leakage light from the bending part 3 is irradiated to the reflecting mirror 200. The reflecting mirror 200 totally reflects the leaked light and enters the probe 12. The probe 12 is installed at a position where the optical coupling efficiency with the leaked light is maximized.

  With such a configuration, as in the ninth embodiment, the leaked light can be collected at an arbitrary position by the reflecting mirror 200, so that restrictions on the size and position of the probe 12 can be relaxed. As a result, the optical coupling efficiency can be increased, and the apparatus can be reduced in size. Of course, since the traveling direction of the light is reversible, the communication light or the test light can be incident on the bent optical fiber 1 from the probe 12 as in the existing apparatus.

  Even if the bending angle of the bent optical fiber 1 is shallow, interference between the probe 12 and the bent optical fiber 1 can be avoided by reflecting the leaked light leaking at a position near the bent optical fiber 1 by the reflecting mirror 200, so that the size of the optical fiber 1 is small. The probe 12 can be installed at an optimum position. Of course, communication light or test light from the probe 12 can be incident on the bent optical fiber 1.

  FIG. 16 shows an optical fiber side input / output device in which the probe 12 shown in FIG. The photodiode 8 is installed at a position where the optical coupling efficiency with the leakage light is maximized. Since the leaked light is collected at an arbitrary position by the reflecting mirror 200, it is possible to install the photodiode 8 without any size or position restrictions. As described above, according to the tenth embodiment as well, restrictions on the installation conditions of the probe 12 and the photodiode 8 can be relaxed, and the same effect as in the ninth embodiment can be obtained.

  As described above, according to each embodiment, it is possible to provide an optical fiber side input / output device and an optical communication switching system that can reliably capture leaked light.

The present invention is not limited to the above embodiment. For example, as the photodiode 8, it is possible to use a PIN photodiode instead of the avalanche photodiode.
The optical arrangement shown in FIG. 11 can of course be applied to the first, second and eighth embodiments.

2, 5, 6, 7, 9, and 13 to 16 are all shown in FIGS. 1, 4, 11, and 12. It can be applied to an optical communication switching system.
In addition, the arrangement of each optical system and the material of the optical component can be variously modified and implemented without departing from the gist of the present invention.

  In short, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Further, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

  DESCRIPTION OF SYMBOLS 1 ... Bending optical fiber, 2 ... Cylindrical part, 3 ... Bending part, 4 ... Refractive index matching agent, 5 ... Probe fiber, 6 ... Wavelength beam splitter, 7 ... TO-can, 8 ... Photodiode, 9 ... Large core diameter Multimode fiber, 10 ... Prism beam splitter, 20 ... Station side transmission device, 30 ... Subscriber side transmission device, 40p ... Optical fiber, 40s ... Optical fiber, 50 ... In-house coupler, 60 ... ONU side closure, 61 ... Temporary light Blocking mechanism, 62 ... Temporary light blocking mechanism, 63 ... Synchronous operation controller, 64 ... WDM coupler, 65 ... Optical amplifier, 66 ... WDM coupler, 67 ... Optical fiber side input / output device, 68 ... Avalanche photodiode, 69 ... Relay amplifier 71 ... Relay amplifier 82 ... Symbol 84 ... Symbol 90 ... OLT side closure 100 ... Prism 200 ... Reflector 11 ... Glass Rock, 12 ... receiving unit, 13 ... glass block, 14 ... bent pressing portions

Claims (8)

An optical fiber side input / output device for inputting / outputting light to / from an optical fiber formed with a bent portion through the bent portion,
An incident optical fiber whose end face is opposed to the bent portion and capable of entering incident light into the bent portion via the end face ;
An optical system that is provided between the bent portion and the end surface and changes a path of leakage light leaking from the bent portion in a direction different from a direction from the bent portion toward the end surface ;
An optical fiber side input / output device comprising: a capturing unit that captures the leaked light whose path has been changed.   The optical fiber side input / output device according to claim 1, wherein the capturing unit includes a light receiving element that receives the leaked light whose path has been changed.   2. The optical fiber side input / output device according to claim 1, wherein the capturing unit includes a multimode optical fiber having a core diameter capable of receiving the leaked light whose path has been changed. 2. The optical fiber side input / output device according to claim 1, wherein the optical system includes a mirror portion that reflects the leaked light in a direction different from a direction from the bent portion toward the end surface . The optical system includes a solid member having light permeability, which forms the bent portion by pressing the optical fiber against a curved surface,
The optical fiber side input / output device according to claim 4, wherein the mirror part is formed in a film shape on the solid member. An optical communication switching system for temporarily bypassing an optical signal transmitted / received between a first device and a second device connected via a first optical fiber to a second optical fiber,
The optical fiber side input / output device according to any one of claims 1 to 5, wherein the bent portion is formed in the first optical fiber.
An optical coupling unit for optically coupling the first optical fiber and the second optical fiber;
The second optical fiber is connected to an incident optical fiber of the optical fiber side input / output device, and is transmitted through the second optical fiber from the first device to the second device as a downlink. A downlink optical transmission system for transmitting an optical signal from the incident optical fiber to the bending unit and transmitting the optical signal to the second device;
A second optical signal that is uplink-transmitted from the second device toward the first device is leaked from the bent portion, and is captured by the capturing unit of the optical fiber side input / output device, and is transmitted through the second optical fiber. And an uplink optical transmission system for transmitting to the first device.   The optical communication switching system according to claim 6, further comprising a relay amplifier that amplifies the captured second optical signal. An optical communication switching system for temporarily bypassing an optical signal transmitted / received between a first device and a second device connected via a first optical fiber to a second optical fiber,
A first closure for accommodating the first optical fiber and the second optical fiber on the first device side;
A second closure for accommodating the first optical fiber and the second optical fiber on the second device side;
The first closure is:
A first optical input / output device using the optical fiber side input / output device according to any one of claims 1 to 5, wherein the bent portion is formed in the first optical fiber;
Leaking the first optical signal transmitted in the downlink from the first device to the second device from the bent portion of the first optical input / output device and capturing it by the capturing portion of the first optical input / output device; A second optical signal transmitted from the second device to the first device via the second optical fiber and uplink transmitted from the second device to the first device is transmitted from the incident optical fiber of the first optical input / output device. A first optical transmission system that is incident on the bending portion and transmits to the first device;
The second closure is
A second optical input / output device using the optical fiber side input / output device according to any one of claims 1 to 5, wherein the bent portion is formed in the first optical fiber;
Leaking the second optical signal from the bent portion of the second optical input / output device, capturing the second optical signal by the capturing portion of the second optical input / output device, and transmitting the second optical signal to the first device via the second optical fiber; An optical communication switching system comprising: a second optical transmission system for transmitting a first optical signal from the incident optical fiber of the second optical input / output device to the bending portion and transmitting the first optical signal to the second device. .

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