JP2013167759A - Optical fiber connection mechanism and method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-loss, simple, and inexpensive butt joint technique for an optical fiber using a solid-state reactive index matching agent, which is applicable to even optical fibers having an air-hole structure.SOLUTION: An optical fiber 32 is inserted to an aligning member 13 fixed to one end of a base member 42 in a state where a holding member 41 is disposed in such a position that an interval between the holding member 41 and the aligning member 13 is equal to a prescribed bending fiber length, and the optical fiber 32 is held by the holding member 41 at the moment when an end surface at the front end of the optical fiber butts against a prescribed solid-state refractive index matching agent 31, and the optical fiber 32 is bent by moving the holding member 41 toward the aligning member 13 till a spacer 43 having the same length as a prescribed bend width is brought into contact with the aligning member 13, whereby a pressing force of 0.1 N or more is applied between the end surface of the optical fiber 32 and the refractive index matching agent 31 to achieve satisfactory connection characteristics.

Description

  The present invention relates to an optical fiber butt connection technique using a solid refractive index matching agent that can be applied not only to a normal single mode optical fiber (SMF) but also to a hole structure optical fiber.

  As a part for connecting an optical fiber, there is an on-site assembly connector capable of easily terminating an optical fiber connector in the field (see Non-Patent Document 1). Termination of the optical fiber by the field assembly connector is performed by connecting the optical fiber to be terminated to the optical fiber (built-in fiber) built in the field assembly connector in advance, and fixing, By interposing an oily refractive index matching agent between the end faces of two optical fibers, it is possible to connect a low-loss, simple and inexpensive optical fiber.

  On the other hand, with the diversification of access-system optical wiring facilities, the introduction of optical fibers with excellent bending loss characteristics is progressing, and a typical example is a hole-structured optical fiber. As a technique for connecting the hole-structured optical fibers, a connection technique using a solid refractive index matching agent has been studied (see Non-Patent Document 2). When applying a solid refractive index matching agent to an on-site assembly connector, it will be performed using the pressing force due to the bending of the optical fiber, but it will try to terminate with the built-in fiber due to insufficient pressing force. There is concern about the deterioration of connection characteristics due to an increase in the end face spacing between the optical fibers.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a low-loss, simple and simple method using a solid refractive index matching agent that can be applied to a hole-structured optical fiber. The object is to provide an inexpensive optical fiber butt connection technology.

  In the present invention, in order to achieve the above-mentioned object, through a solid refractive index matching agent having a length (thickness) with respect to the longitudinal direction of the optical fiber of 100 μm to 120 μm and a hardness of Shore A of 30 to 40, Appropriate pressing force is obtained by using a connecting jig that deflects the optical fiber at the time of abutting the optical fiber so that the bending width of the optical fiber is 18 mm or less and the difference between the bending fiber length and the bending width is 2 mm or more and 6 mm or less. Thus, an object of the present invention is to provide a simple optical fiber connection mechanism and connection method that realizes good connection characteristics applicable to a hole-structured optical fiber.

  According to the present invention, by appropriately bending the optical fiber, a sufficient pressing force for deforming the solid refractive index matching agent is obtained, and it can be applied to a hole structure optical fiber. If it is obtained by using a refractive index matching agent, it is possible to obtain the same connection loss.

  Specifically, a jig that obtains a pressing force of 0.1 N or more with a bending width of the optical fiber of 18 mm or less and a difference between the bending fiber length and the bending width of 2 to 6 mm with the optical fiber bent. Solid refractive index matching applicable to a hole-structured optical fiber having a length (thickness) corresponding to the longitudinal direction of the optical fiber of 100 μm to 120 μm and a hardness of 30 to 40 for Shore A. The agent is deformed, and an effect that a connection loss similar to that of oil can be obtained is exhibited.

It is a graph which shows the histogram of the connection loss regarding the field assembly connector using a solid state and oil-like refractive index matching agent. It is a partial cross section schematic diagram which shows the model of termination work of the optical fiber by a field assembly connector. It is a graph which shows the relationship between the bending width and connection loss in a field assembly connector. It is a graph which shows the relationship between the bending width of an optical fiber, and pressing force. It is a graph which shows the relationship between the bending width with respect to the fiber length to bend, and pressing force. It is a graph which shows the relationship between the fiber length and the bending width which can obtain the theoretical pressing force of 0.1 N or more. It is a partial section lineblock diagram showing a 1st embodiment of a connection mechanism of an optical fiber of the present invention. It is a partial cross section block diagram which shows 2nd Embodiment of the connection mechanism of the optical fiber of this invention. It is a partial cross section block diagram which shows 3rd Embodiment of the connection mechanism of the optical fiber of this invention. It is a partial cross section block diagram which shows 4th Embodiment of the connection mechanism of the optical fiber of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, connection loss when a solid refractive index matching agent was used and when an oily refractive index matching agent was used was evaluated for a known on-site assembly connector. The solid refractive index matching agent used had a length (thickness) corresponding to the longitudinal direction of the optical fiber of 100 μm to 120 μm and a hardness of 30 to 40 for Shore A.

  FIG. 1 shows a connection loss histogram for a field assembled connector using solid and oily refractive index matching agents. From the figure, the average value of connection loss obtained when using a solid refractive index matching agent is 0.94 dB, and the average value of connection loss obtained when using an oily refractive index matching agent is 0.41 dB. From this, it can be seen that the solid material has a larger connection loss than the oil material. When the distance between the end faces between the built-in fiber of each sample and the optical fiber to be terminated is measured after connection, when the solid refractive index matching agent is used, the refractive index matching agent is not crushed and the maximum is 80 μm. There was an interval. Accordingly, it is understood that the loss due to the end face spacing between these optical fibers is increased, and the loss in the solid state is larger than that in the oil state.

  Next, in the termination work of the optical fiber by a known field assembly connector, the influence on the connection loss depending on the end face interval in the connected state when the pressing force due to the bending of the optical fiber was increased was evaluated.

  FIG. 2 shows a model of optical fiber termination work by a field assembly connector. Here, the field assembly connector 10 is built and fixed in the through hole of the ferrule 11 so that the ferrule 11 having a through hole capable of accommodating an optical fiber and one end of the ferrule 11 coincide with one end surface (connection end surface) of the ferrule 11. The optical fiber (built-in fiber) 12 and the other end side of the ferrule 11 are integrally coupled, and the other end of the built-in fiber 12 protruding from the other end side is connected to the tip of the optical fiber to be terminated and the mechanical splice. It is composed of an aligning member 13 that can be butt-connected in an aligned state using a mechanism.

  The termination operation using the on-site assembly connector 10 described above is performed by adjusting the refractive index to a position where the other end of the built-in fiber 12 is in contact with the alignment member 13 opened by a wedge (not shown) or the like. The tip 21 of the optical fiber 23 held by the holding member 22 is inserted and the holding member 22 is moved in the direction of the aligning member 13 while the aligning member 13 is fixed. In the state where the tip of the optical fiber 23 is pressed against the other end of the built-in fiber 12 via the refractive index matching agent 21 by the pressing force due to the bending, the wedge is removed and the aligning member 13 is closed. This is done by fixing the built-in fiber 12 and the optical fiber 23. The optical fiber 23 actually extends to the right side of the gripping member 22, but is omitted from the drawing.

  In the present invention, the interval between the aligning member 13 and the gripping member 22 at the time of fixing is referred to as a “deflection width”. The distance between the aligning member 13 and the gripping member 22 in a state before 23 is bent is referred to as a “flexible fiber length”, but the pressing force is changed by adjusting the bending width (the shorter the shorter the shorter the shorter). The pressing force increases).

  FIG. 3 shows the relationship between the deflection width and the connection loss in the field assembly connector using the solid and oily refractive index matching agents. FIG. 3 shows that the loss is reduced when the bending width is shortened. In particular, when the deflection width is shortened to 18 mm or less, it can be seen that the loss of the solid refractive index matching agent is comparable to the loss of the oily refractive index matching agent.

  FIG. 4 shows the relationship between the deflection width and the pressing force. In the figure, the solid line indicates the theoretical value (see Non-Patent Document 3), and the plot indicates the measured value. From FIG. 4, it can be confirmed that the theoretical value and the measured value are in good agreement.

  3 and 4, it is understood that by applying a pressing force of 0.1 N or more, the solid refractive index matching agent can obtain the same loss characteristics as the oily refractive index matching agent.

  The relationship between the bending fiber length and the bending width at which the pressing force is 0.1 N or more was examined. FIG. 5 shows the relationship between the bending width and the pressing force with respect to the bending fiber length. Regardless of the length of the bending fiber, the pressing force almost depends on the bending width, but the pressing force at the beginning of bending is smaller than the theoretical value indicated by the solid line, and it can be seen that the variation is large. Moreover, when the fiber length bent with respect to a bending width is too long, it becomes a pressing force smaller than a theoretical value. For example, when the length of the bending fiber is 25 mm, the pressing force is 0.097 N when the bending width is 18 mm, which is smaller than the theoretical pressing force. Therefore, in order to obtain a theoretical pressing force of 0.1 N or more, it can be seen that there is an upper limit value and a lower limit value in the difference between the fiber length and the bending width that are bent according to the bending width.

  FIG. 6 shows the relationship between the bending fiber length and the bending width at which a theoretical pressing force of 0.1 N or more is obtained. In the region below the solid line in the figure, that is, in the region where the difference between the length of the deflected fiber and the deflection width is 2 mm or more and 6 mm or less, a pressing force of 0.1 N or more can be obtained.

  FIG. 7 shows a first embodiment of the optical fiber connection mechanism of the present invention. In the figure, the same components as those in FIG. That is, 10 is an on-site assembly connector comprising a ferrule 11, a built-in fiber 12, and an alignment member 13, 31 is a refractive index matching agent, 32 is an optical fiber to be connected (terminated), and 40 is a connection jig.

  Here, the refractive index matching agent 31 is a solid having a length (thickness) corresponding to the longitudinal direction of the optical fiber of 100 μm to 120 μm and a hardness of 30 to 40 in Shore A.

  The connection jig 40 includes a gripping member 41 that grips the optical fiber 32, a base member 42 that holds the alignment member 13 fixedly and holds the gripping member 41 slidably in the longitudinal direction of the optical fiber, Means for regulating the interval between the aligning member 13 and the gripping member 41 so as not to become a predetermined deflection width, that is, 18 mm or less, here, a spacer 43 having the same length as the deflection width attached to the gripping member 41. It is made up of.

  Then, in the termination of the optical fiber 32 with respect to the on-site assembly connector 10 using the connection jig 40, first, the alignment member 13 is fixed to one end of the base member 42, and the distance from the alignment member 13 is predetermined. The gripping member 41 is disposed at a position where the difference between the length of the fiber, i.e., the above-described bending width is equal to the length of 2 mm to 6 mm. Next, the aligning member 13 is opened by a wedge (not shown) or the like, the refractive index matching agent 31 is disposed at a position in contact with the other end of the built-in fiber 12, and the optical fiber 32 is straightened. 13, and the optical fiber 32 is gripped by the gripping member 41 at the moment when the end face of the leading end abuts against the refractive index matching agent 31. FIG. 7A shows the state at this time as viewed from above. Although not shown, the optical fiber 32 actually extends to the right side of the gripping member 41.

  Next, while holding the optical fiber 32, the holding member 41 is slid in the direction of the aligning member 13 until the spacer 43 comes into contact with the aligning member 13, and the optical fiber 32 is bent. FIG. 7B shows the state at this time viewed from the side (note that the bending of the optical fiber 32 is exaggerated from the actual state for the sake of clarity).

  At this time, the tip of the optical fiber 32 is pressed against the other end of the built-in fiber 12 through the refractive index matching agent 31 by the pressing force due to the bending of the optical fiber 32, that is, the pressing force of 0.1 N or more. In this state, the wedge or the like is removed, the alignment member 13 is closed, and the built-in fiber 12 and the optical fiber 32 are fixed, whereby the optical fiber 32 is terminated to the field assembly connector 10.

  Thereafter, by releasing the gripping state of the gripping member 41 and releasing the fixing state of the alignment member 13 with respect to the base member 42, the field assembly connector 10 having the optical fiber 32 terminated is removed.

  FIG. 8 shows a second embodiment of the optical fiber connection mechanism of the present invention, in this case, as a means for regulating the distance between the aligning member 13 and the gripping member 41 so as not to be less than a predetermined deflection width. 13 or an example in which the spacer 44 having the same length as the predetermined deflection width attached to the fixing position of the alignment member 13 of the base member 42 is shown. Other configurations and operations are the same as those in the first embodiment.

  FIG. 9 shows a third embodiment of the optical fiber connecting mechanism according to the present invention. Here, the base member 42 is used as a means for regulating the distance between the aligning member 13 and the gripping member 41 so as not to be less than a predetermined deflection width. The example using the stopper 45 attached to the position where the distance from the aligning member 13 corresponds to the predetermined deflection width is shown. Other configurations and operations are the same as those in the first embodiment.

  FIG. 10 shows a fourth embodiment of the optical fiber connecting mechanism according to the present invention, in this case, as a means for regulating the distance between the aligning member 13 and the gripping member 41 so as not to be less than a predetermined deflection width. The spacer 46a and the spacer 46b attached to the fixing position of the aligning member 13 of the base member 42 or the aligning member 13 (however, the total length of the spacers 46a and 46b is the same as the predetermined deflection width). An example using "." Other configurations and operations are the same as those in the first embodiment.

  In the fourth embodiment, when the total length of the two spacers 46a and 46b is 17 mm and the length of the bending fiber is 20 mm, the connection loss of the field assembly connector is evaluated (the number of samples is 5). The average value was 0.44 dB, and the maximum value was 0.63 dB, confirming that the characteristics were good.

  The fixing of the optical fiber to the aligning member using the function of the mechanical splice is generally simultaneous with the two optical fibers to be connected, but the field assembly connector described in the embodiment. In the case of the aligning member, since the built-in fiber is fixed to the ferrule coupled to the aligning member, it can be said that it is fixed at least in the longitudinal direction as stated in the claims.

  10: field assembly connector, 11: ferrule, 12: built-in fiber, 13: alignment member, 31: refractive index matching agent, 32: optical fiber, 40: connection jig, 41: gripping member, 42: base member, 43 , 44, 46a, 46b: spacer, 45: stopper.

Terakawa, Sasamori, Nakajima, Tanase, Toyonaga, Kama, "Aerial connection technology to realize mass optical installation work", Shinso Univ., B-10-5, 2006. K. Saito, R. Koyama, Y. Abe, K. Nakajima, and T. Kurashima, "Optimum mechanical splice conditions for fiber with hole-assisted structure," in Proceedings of Optical Fiber Communication Conference and Exposition (OFC), NThB5, (2010). Abe, Kihara, Kobayashi, Matsui, Yodogawa, Nagase, Iwata, "Study of on-site assembly PC connector that does not require fiber end polishing", Shinso Univ., B-13-14, 2008.

Claims (4)

The other optical fiber held by the holding member is inserted into the alignment member in which one of the two optical fibers to be connected is fixed at least in the longitudinal direction, and the alignment member And the gripping member are made shorter than the total length of the other optical fiber between them, the other optical fiber is bent, and the pressing force due to the bending between the end faces of the two optical fibers is reduced. An optical fiber connection mechanism for connecting the two optical fibers by being fixed to the alignment member in a state of being added,
A solid refractive index matching agent having a length corresponding to the longitudinal direction of the optical fiber of 100 μm to 120 μm and a hardness of Shore A of 30 to 40 is provided between the end faces of the two optical fibers. ,
The bending fiber length which is the total length of the other optical fiber held in a state where the bending width which is the interval between the alignment member and the gripping member when fixed is 18 mm or less and is bent within the interval of the bending width And a connecting jig for abutting the two optical fibers so that the difference between the bending width and the bending width is 2 mm or more and 6 mm or less,
Using the connecting jig, a tip is inserted into the aligning member and an end surface of the gripping member is disposed at a position where the distance from the aligning member is equal to the length of the bending fiber. The other optical fiber that is in contact with the refractive index matching agent is gripped, the gripping member and the aligning member are moved in a relatively approaching direction, and the interval therebetween is set as the bending width, and in that state, the 2 An optical fiber connection mechanism characterized in that a single optical fiber is fixed to the alignment member. The connecting jig is
Together with a gripping member for gripping the other optical fiber,
A base member that holds the alignment member fixedly and holds the gripping member slidably in the longitudinal direction of the optical fiber;
The optical fiber connection mechanism according to claim 1, further comprising means for regulating an interval between the alignment member and the gripping member so as not to be equal to or less than the bending width. The regulating means is
A spacer having the same length as the deflection width attached to the gripping member, a spacer having the same length as the deflection width attached to a fixing position of the alignment member or the alignment member of the base member, or the base The optical fiber connection mechanism according to claim 2, further comprising a stopper attached at a position where the distance of the member from the alignment member corresponds to the bending width. The other optical fiber held by the holding member is inserted into the alignment member in which one of the two optical fibers to be connected is fixed at least in the longitudinal direction, and the alignment member And the gripping member are made shorter than the total length of the other optical fiber between them, the other optical fiber is bent, and the pressing force due to the bending between the end faces of the two optical fibers is reduced. An optical fiber connection method for connecting the two optical fibers by fixing the two optical fibers to the alignment member in a state of being added,
A solid refractive index matching agent having a length corresponding to the longitudinal direction of the optical fiber of 100 μm to 120 μm and a hardness of Shore A of 30 to 40 is interposed between the end faces of the two optical fibers;
The bending fiber length which is the total length of the other optical fiber held in a state where the bending width which is the interval between the alignment member and the gripping member when fixed is 18 mm or less and is bent within the interval of the bending width And a position where the distance from the aligning member is equal to the length of the deflected fiber by using a connecting jig for abutting the two optical fibers so that the difference between the bend width and the bend width is 2 mm or more and 6 mm or less. The gripping member disposed in the gripping member is gripped with the other optical fiber having a tip inserted into the aligning member and an end surface of the gripping member being in contact with the solid refractive index matching agent. The optical fiber connecting method is characterized in that the two optical fibers are fixed to the aligning member in the state where the distance between them is moved in a relatively approaching direction so that the interval therebetween is the bending width.