JPS599615A - Optical fiber connector - Google Patents

Abstract

PURPOSE:To arrange an optical fiber at a specific position easily by interposing a transparent member between a lens body and an optical fiber support, and arranging the optical fiber support with an insertion hole for the optical fiber at a cylindrical member. CONSTITUTION:An optical fiber plug 22 is equipped with a nearly cylindrical ferrule 1, wherein a convex lens 5, spacer 6, and optical fiber support 7 are incorporated successively. The lens 5 and spacer 6 are made of optically transparent and nearly columnar media such as glass; and the refractive index of the spacer 6 is uniform, both ends are made of flat transparent media, and the end surface on the opposite side to the lens 5 is thick enough to position the focus of the lens 5. The base 7 is made of metal nearly in a columna shape and the through hole 9 for the optical fiber is formed at the axial core part of the base 7. Consequently, the optical fiber is arranged at the specific position extremely easily.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a source fiber connector used for optically connecting source fibers to each other or source fibers to other equipment.

This type of fiber connector, for example, an optical fiber plug, has a conventional structure as shown in FIG. In this FIG. 1, each plug (21a) (21b) is
Cylindrical fer-71/ (ia) (ib), co0)
A gradient index lens (2aX2b) fitted into the hollow part of a 7-erule (18X1b) and whose length is an odd multiple of the % pitch of the original meandering period and a C(1) L/7 lens (2
aX2b) 0) Original fiber spliced approximately at the axial center position (
3aX3b).

When the end faces of such a plug (218x21b) are placed opposite each other, the light (4) emitted radially from one end face of the optical fiber (3a) is refracted by the lens (2a). As a result, at the end face position of this lens (2a), the light (4J) is approximately parallel to the axis of the lens (2a).Then, the light (4) is further bundled in the opposing lens (2b). Therefore, it is optically connected to the original fibers (6a) and (3b).

By the way, the ideal distribution of the refractive index N of a gradient index lens is N = N(15ech (y'Kr )A Ticket A =No (1--r2+ -)2r'-"C")
3r'-1-'','',)2902 It is expressed as t. Here, A is called a refractive index distribution constant, and the larger this distribution constant is, the more the light (4) emitted from the eyeglass (6a) or (3b) will be affected by the lens (2a) or (2b). The spread at the end face becomes larger.

However, currently it is difficult to increase this distribution constant beyond a certain level, and as a result, when using a normal optical fiber (core diameter = 50 μm, numerical aperture = 0.20), the spread of light is 40 μm of the lens diameter. The limit is about 50%. Therefore, a gradient index lens (2a
] or (2b) using plug (21a) or (21
In b), even if the axial center of the plug is slightly shifted from the axial center of the opposing plug, the original coupling loss is large. Figure 2 1.
The relationship between the amount of axis deviation and the coupling loss of light is shown, and the curve with a steep slope in the graph of FIG. 2 is for a gradient index lens. Here, the coupling loss means that the circular cross-sectional area of the element (4) emitted from the lens (2a) is So, and the other lens (2) of this emitted element (4) is
The cross-sectional area of the light (4) when it enters the lens (2) is 81
When , it is defined as . This formula is expressed as: 1 Coupling loss -io iog; (2d) is the diameter of the light (4) emitted from the lens (2a), r is the axis deviation amount, and θ-CO5-1 (r/2d); θ-pin 2θ)
[dB:]. In this formula, lens (2a)
The diameter of (2b) is 2 mm, and the diameter of the injection source (4) is 2 mm.
The above idea in FIG. 2 is obtained when d is 1 mm.

The above equation showing the refractive index N is an ideal distribution, and if the refractive index distribution follows the above equation, an ideal lens without aberrations will be obtained. However, it is not easy to control the higher-order terms in the above equation, and as a result, aberrations remain, and as a result, the plug (218x21b) used with a gradient index lens (28x2b) f as shown in Figure 1 is The coupling loss is large.

10,000, In the original fiber connector as shown in Figure 1,
If a convex lens is used instead of a gradient index lens (2aX2b) as a condensing/parallel light converting lens body, the diameter of the human emitted light beam drawn in relation to the circular cross-sectional area So described above will be approximately equal to the diameter of the lens. It is possible to do so. Therefore, the diameter of the light emitted from the original fiber can be expanded to be approximately equal to the diameter of the convex lens, and therefore the coupling loss of light due to axis misalignment can be reduced. For example, the coupling loss when the diameter of the convex lens and the inclination of the ejected original are also 2 mm is shown by a curve with a gentle slope in the graph of FIG.

In addition, convex lenses generally have less aberration than gradient index lenses, so if a convex lens is used as described above, the aberration ζ will be reduced compared to the original fiber plug with the configuration shown in Figure 1. Low coupling loss.

However, as mentioned above, when a convex lens is used as a lens body for condensing and collimating light, it is generally necessary to precisely position the tip of the optical fiber at the focal point of the convex lens, which is located an appropriate distance away from the convex lens. There is. Therefore, the task of arranging the optical fiber at a predetermined position relative to the convex lens is extremely troublesome.

The present invention was invented to solve the above-mentioned problems, and even when a convex lens is used as the lens body, it is extremely easy to arrange the original fiber at a predetermined position with respect to the lens body. I'm trying to provide something.

Embodiments of the present invention will be described below with reference to FIGS. 3 and 4.

FIG. 6 shows an embodiment of an original fiber plug according to the invention. In FIG. 3, the plug (221) is completely equipped with a substantially cylindrical ferrule (1),
), a convex lens (5), a spacer (6), and an optical fiber support (the blades are installed in this order in a state where they are in contact with each other).The ferrule (1) is made of metal such as stainless steel, synthetic resin, ceramics, etc. It consists of a lens (
5) and the spacer (6) are composed of an optically transparent substantially cylindrical medium such as glass or synthetic resin, and the spacer (6) is a transparent frame whose refractive index is uniform and both ends are flat. The lens (5) may be attached to the end surface opposite to the lens (5).
) has a thickness such that the focal point of the area is located. The support (sword) is made of glass, synthetic resin, metal, ceramics, etc. and is approximately cylindrical, and its outer diameter is somewhat smaller than the inner diameter of the ferrule (1). There is an insertion hole (9) in the delicate part for inserting the original fiber.
is formed, and the outer end of this insertion hole (9) is a tapered opening QOI. In order to protect the lens (5), a cover glass (8) may be provided at one end of the ferrule (1) if necessary.

The fourth step is to assemble the plug (221) with the above configuration.
This will be explained with reference to the diagram. No need ferrule (lens inside 11)
5) and spacer (6) are adhesively fixed, the support (7) is simply inserted into the ferrule (1) without adhesive, and this is inserted into the support in front of the collimated light source (lυ) as shown in Figure 4. Fix the device (1'lJ) and insert the source fiber 03 for light intensity measurement into the insertion hole (9) of the support (7), and place the tip of this source fiber in a dense layer on one end surface of the spacer (6). Connect another original fiber plug (23) to the other end of the bent original fiber (1 wrinkle) in advance.This other original fiber plug (c) is also substantially the same as the one shown in FIG. They may have the same configuration and have already been assembled.

Then, the light emitted from the optical fiber, ii f(13+) is converted into parallel light by the other original fiber plug (2:(l), and this parallel light is received by Measure with monitor a power.In the above measurement system, light source 0
Parallel light beam from υ (181r, r plug + input to lens (5) in 221), monitor OD to the °C fiber (
13) While measuring the amount of transmitted light, the support inside the plug (
7) in a direction perpendicular to the original axis to the position where the light-receiving pair shows its peak.
) Find the γ position where the center lines of the lines match. At this position, the support (7) is fixed with an adhesive (141, etc.), and the original fiber 0.3 is extracted from the support (7).

When using the original fiber plug assembled in the above procedure, transport this plug (22) to the place of use, and attach the tip of the original fiber (3) to be connected to the support ( 7) through the insertion hole (9) and its end face is brought into close contact with the end face of the spacer (6).In this state, the tapered opening (10) is filled with adhesive (15), etc., and the support member ( 7) fix the original fiber (3).

Although the present invention has been described above with reference to embodiments, the present invention is not limited to these embodiments and can be further modified in various ways.

For example, the condensing/parallel light converting lens body may be a spherical lens other than a convex lens, a gradient index lens, or a combination of these lenses.

It is also possible to use a gradient index lens as a suitable support.

As described above, in the present invention, a transparent member is interposed between the lens body and the original fiber support body in contact with both of them, so that the end face of the optical fiber is aligned with respect to the lens body in the optical axis direction. The operation of placing it at a predetermined position a predetermined distance apart is easy. In addition, since the original fiber support having the insertion hole for the original fiber is arranged in the cylindrical member, it is easier to insert the original fiber into the lens body than in the case where one end of the original fiber is inserted through the insertion hole provided directly in the cylindrical member. The radial alignment of the source fiber with respect to the fiber is also easy. Therefore, according to the present invention, it is extremely easy to deposit the lens body (with respect to the original fiber) at a predetermined distance in the axial direction of the lens body and with accurate alignment in both the axial direction and the radial direction.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view showing the state of use of a conventionally known original fiber plug, Fig. 2 is a graph showing the original coupling loss due to axial slippage, and Fig. 6 is a diagram of the original fiber plug to which the present invention is applied. A schematic cross-sectional view of one embodiment, FIG. 4 is a schematic diagram showing the assembly procedure of the original fiber plaque shown in FIG.・
・・・・・・・・・・・・ Ferrule (5)・・・・
・・・・・・・・・Convex lens (61・・・・・・・
・・・・・・・・・Spacer (7)・・・・・・・・・
...Original fiber support (9) ...
......It is an insertion hole. Agent Masaru Ueya, Yoshio Tsune, Shun Sugiura, Mitsugu Figure 1 Figure 2 Nakayamazu'#L quantity [7F1? yl] Figure 3 Figure 4

Claims (1)

[Claims] a cylindrical member; a lens body disposed at one end of the hollow portion of the cylindrical member; a source fiber support body disposed at the other end of the hollow portion and having an insertion hole for the source fiber; The lens body and the original fiber support are interposed so as to be in contact with both of them, so that the parallel light focused by the lens body is converged on the end face of the original fiber support. An optical fiber connector consisting of a transparent member.