JP5771170B2 - Optical fiber connection member - Google Patents

Description

  The present invention relates to an optical fiber connecting member.

  When aligning and fixing an optical fiber with a waveguide-type optical element having an optical waveguide provided on a substrate such as a planar lightwave circuit (PLC), the bonding cross-sectional area is widened to increase the mechanical strength of the bonded portion. In addition, an optical fiber connecting member made of glass or the like is used. For example, there are a V-groove glass substrate (V-groove fiber block), a ferrule, and the like. An optical fiber is fixed to such an optical fiber connecting member, and the optical fiber connecting member is bonded to the waveguide type optical element.

  Here, taking a PLC-LN (lithium niobate) modulator as an example, the package of the PLC-LN modulator uses a metal material having a thermal expansion coefficient close to that of the LN crystal. The optical fiber is connected to the PLC end face at both ends of the package, and is fixed at the two locations. Since the thermal expansion coefficient of the optical fiber is one digit or more smaller than the thermal expansion coefficient of the LN crystal, a tensile stress is applied to the fiber portion at a high temperature and a compressive stress at a low temperature. Therefore, a buckling structure is put in the optical fiber in advance so that the optical fiber does not break with respect to temperature fluctuation.

  Referring to FIG. 1, when the ferrule 100 used as the optical fiber connecting member is long, the total length of the package is limited by standards and the like. Becomes shorter. For this reason, the curvature of the optical fiber 10 is increased, which may lead to disconnection of the optical fiber. On the contrary, if the length of the ferrule 100 is shortened, it becomes difficult to hold the ferrule 100, and the jig 20 becomes close to the connection surface 100A of the ferrule 100 with the waveguide type optical element 30 and is bonded at the time of mounting. The agent 40 may adhere to the jig 20.

  Here, the “ferrule” means a columnar optical fiber connecting member having a fine hole (cavity) into which an optical fiber is inserted and capable of holding, positioning, and protecting the optical fiber. For example, glass, metal However, any of the ferrules has the above-mentioned problems.

JP 2012-37731 A

  The present invention has been made in view of such problems, and an object of the present invention is to provide an optical fiber connecting member to which an optical fiber is fixed for connection with a waveguide type optical element. An object of the present invention is to provide an optical fiber connecting member capable of reducing the curvature when bent.

In order to achieve such an object, a first aspect of the present invention provides a cavity for fixing an optical fiber in an optical fiber connecting member to which the optical fiber is fixed for connection with a waveguide type optical element. And a recess provided around the cavity on the surface facing the connection surface with the waveguide optical element, the recess being a slit-shaped recess, and the light of the waveguide optical element It characterized that you have formed the direction of the slit perpendicular to the waveguide plane.

According to a second aspect of the present invention, in the first aspect , a plurality of the slit-like recesses are formed.

According to a third aspect of the present invention, in the first or second aspect, the slit-shaped recess has an inclined portion in contact with the cavity.

  According to the present invention, the curvature when the optical fiber is buckled is reduced by providing the concave portion around the cavity for fixing the optical fiber on the surface facing the connection surface with the waveguide type optical element. be able to.

It is a figure which shows the conventional optical fiber connection member. It is a figure which shows the optical fiber connection member which concerns on the 1st Embodiment of this invention. It is a figure which shows the deformation | transformation form of the optical fiber connection member which concerns on 1st Embodiment. It is a figure which shows the optical fiber connection member which concerns on the 2nd Embodiment of this invention. It is a figure which shows the manufacturing method of the optical fiber connection member which concerns on 2nd Embodiment. It is a figure which shows the insertion method of the optical fiber to the optical fiber connection member which concerns on 2nd Embodiment. It is a figure which shows the optical fiber connection member which concerns on the 3rd Embodiment of this invention. It is a figure which shows the manufacturing method of the optical fiber connection member which concerns on 3rd Embodiment. It is a figure which shows the optical fiber connection member which concerns on the 4th Embodiment of this invention. It is a figure which shows the manufacturing method of the optical fiber connection member which concerns on 4th Embodiment.

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

  FIG. 2 shows an optical fiber connection member according to the first embodiment of the present invention. The optical fiber connection member 200 has a cavity 201 for fixing an optical fiber, and includes a recess 202 around the cavity 201 on a surface 200B facing the connection surface 200A with the waveguide optical element 30.

  By providing the recess 202 around the cavity 201 on the surface 200B facing the connection surface 200A, the buckling structure 10A of the optical fiber 10 starts from inside the optical fiber connection member 200. Therefore, the area that can be secured for the buckling structure 10A of the optical fiber 10 can be increased without shortening the optical fiber connection member 200, and the curvature of the optical fiber 10 can be reduced.

  In FIG. 2, a cylindrical shape is illustrated as the shape of the recess 202, but the strength of the ferrule can be increased if the shape is a tapered shape (FIG. 3A) in which the cross-sectional area gradually decreases from the surface 200 </ b> B. For this reason, it is possible to prevent the ferrule from being damaged by the fixing jig 20.

  In addition, the closer the optical fiber in the ferrule is to the connection surface 200B, the higher the degree of freedom of position variation. Although there is a possibility, contact with an optical fiber can be prevented by having such a tapered shape.

  Further, in the case of the taper shape, if the side wall of the concave portion 202 is a curved surface, the probability of touching the edge portion of the inner diameter of the ferrule is reduced, and the effect of preventing disconnection is higher (FIG. 3B). In this case, the contact probability can be further reduced by increasing the curvature of the curved surface as it is closer to the surface 200B.

  If the curvature radius R (= 1 / κ) of the curved surface is too small, radiation loss occurs due to the bending of the optical fiber. When r is the minimum bending radius of the optical fiber, optical connection is possible without causing radiation loss if R ≧ r at any position on the tapered surface. In the case of a general single mode optical fiber, R ≧ 30 mm. However, when using a bending-resistant optical fiber such as a high refractive index difference optical fiber or a hole assist fiber (HAF), R should be further reduced. Thus, a configuration such as R ≧ 15 mm, R ≧ 7.5 mm, and R ≧ 5 mm is possible.

  If the total length of the ferrule is L and the length of the concave portion is 1, if the length of l is too long (the concave portion is too deep), the bonding area between the optical fiber and the ferrule becomes small, and there is a possibility that the bonding strength cannot be obtained. . When a general optical fiber and an optical fiber connecting member are used, it is desirable that l ≦ L / 2. When a general optical fiber connecting member is used, it is desirable that the total length L of the ferrule is 1 mm or more and 4 mm or less. If L is 1 mm or more, it can be fixed by a jig at the time of mounting, and if L exceeds 4 mm, it is difficult to reduce the size of the package.

  FIG. 4 shows an optical fiber connecting member according to the second embodiment of the present invention. (A) is a top view, (b) is a side view. The optical fiber connection member 300 includes a cavity 301 for fixing the optical fiber, and includes a slit portion 302 around the cavity 301 on a surface 300B facing the connection surface 300A with the waveguide optical element 30. With the slit portion 302, the area that can be secured for the buckling structure of the optical fiber 10 can be lengthened, and the curvature of the optical fiber 10 can be reduced.

  In FIG. 5, the manufacturing method of the optical fiber connection member which concerns on 2nd Embodiment is shown. With such slit-shaped recesses, it is possible to collectively form the optical fiber connection members 300 arranged in a straight line by grinding in the production of the optical fiber connection member. Further, the inclined portion 303 can be formed simultaneously with the grinding from the shape of the blade 311 of the grinding apparatus, and the manufacturing cost can be reduced.

  FIG. 6 shows a method of inserting an optical fiber into the optical fiber connecting member according to the second embodiment. Since the slit portion 302 has the inclined portion 303 in contact with the cavity 301, the optical fiber 10 can be easily inserted into the optical fiber connection member 300, and the cost of the assembly process can be reduced. Since the inclined portion 303 is produced based on the shape of the blade used in the grinding process for producing the optical fiber connecting member 300, no special process is added.

  FIG. 7 shows an optical fiber connecting member according to the third embodiment of the present invention. In the optical fiber connecting member 400, a plurality of slit portions 402-1 and 402-2 are formed perpendicular to the plane of the optical waveguide 32 formed on the substrate 31 of the waveguide type optical element 30. A multi-core optical connection component capable of simultaneously connecting two optical fibers to two optical waveguides can be configured.

  In FIG. 8, the manufacturing method of the optical fiber connection member which concerns on 3rd Embodiment is shown. Similar to the second embodiment, the optical fiber connecting members 400 arranged in a straight line can be collectively formed by grinding.

  In the third embodiment, in order to make this structure easy to understand, a component having two slits has been described in order to connect two optical fibers and an optical waveguide. However, the number of slits is not limited to two. Absent.

  FIG. 9 shows an optical fiber connecting member according to the fourth embodiment of the present invention. In the optical fiber connection member 500, a slit portion 502 is formed in parallel to the plane of the optical waveguide 32 formed on the substrate 31 of the waveguide type optical element 30. The slit portion 502 has a plurality of cavities 501-1 to 501-3 for fixing optical fibers. A multi-core optical connection component capable of simultaneously connecting three optical fibers to three optical waveguides can be configured. Of course, the number of cavities is not limited to three.

  In FIG. 10, the manufacturing method of the optical fiber connection member which concerns on 4th Embodiment is shown. In the production of the optical fiber connection member, the optical fiber connection members 500 arranged in a straight line can be collectively formed by grinding. In addition, the inclined portion 503 can be formed at the same time as the grinding, and the manufacturing cost can be reduced.

DESCRIPTION OF SYMBOLS 10 Optical fiber 10A Buckling structure 20 Jig 30 Waveguide type optical element 31 Board | substrate 32 Optical waveguide 33 Glass block 200,300,400,500 Optical fiber connection member 200A, 300A Connection surface 200B. 300B Surfaces facing the connection surfaces 200A and 300A 201, 301, 401, 501 Cavity 202 Recessed portions 302, 402, 502 Slit portions 303, 403, 503 Inclined portions 311, 411, 511 Blades

Claims (3)

In an optical fiber connecting member to which an optical fiber is fixed for connection with a waveguide type optical element,
A cavity for fixing the optical fiber;
A concave portion provided around the cavity on a surface facing the connection surface with the waveguide type optical element;
The optical fiber connecting member, wherein the concave portion is a slit-shaped concave portion, and the direction of the slit is formed perpendicular to the optical waveguide plane of the waveguide type optical element.   The optical fiber connecting member according to claim 1, wherein a plurality of the slit-shaped recesses are formed. Wherein the slit-like recess, according to claim 1 or 2, wherein the optical fiber connecting member and having an inclined portion in contact with the cavity.

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