JPS5933422A - Optical branching and coupling device - Google Patents

Abstract

PURPOSE:To branch uniformly light and to reduce the optical transmission loss and to make the device small-sized, by laminating flexible optical waveguide films so that their optical coupling waveguide parts are brought together and connecting their end faces to both ends of a mixing plate. CONSTITUTION:An optical branching waveguide 5 and a mixing waveguide 6 are formed in an optical waveguide film 7, and low-refractive index layers having a thickness of about several mum are formed on both faces. Plural films 7 are prepared and are brought into close contact with each other in their coupling waveguides 8 so that optical coupling circuits overlap one another accurately, and an optical fiber row 2 is connected and fixed to a row of optical branching waveguides 5. Two materials constituted in this manner are used as an input end 9 and an output end 9', and they are connected to both end faces of a mixing plate 1 which is formed independently. The incident light from one optional fiber is made incident to the plate 1 through the waveguide 8 and is mixed and passes through all waveguides 5 and is branched uniformly to a fiber row 2'.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical branching coupler used in an optical fiber transmission system. For example, in a data bus using optical fibers, an optical branch/coupler is essential so that optical signals can be exchanged freely between a large number of computers and various terminal devices.

Conventionally, a component having such a function is mainly a mixing plate as shown in FIG. 1. In other words, an input optical fiber array 2 with several TV optical cores closely aligned on the end face of the mixing plate 1, and a line 1 of input optical fibers formed in the same way on the Qll end face.
14 power optical fiber rows 2' are connected to each other, and the light incident on the mixing plate 1 from any one of the input optical fiber rows 2 is connected to the mixing plate 1.
The optical fibers are mixed while propagating within the fiber 1 node, and are evenly branched to the output optical fiber array 2' connected to the other end. By the way, in this type of optical branching coupler, a part of the light from the mixing plate 1 is transmitted to the output optical fiber array 2'.
into the cladding 4 of each optical fiber, the excess loss is inherently high.

Furthermore, when the number of input/output fibers increases, the mixing plate 1 must be made longer in order to branch light equally to each output optical fiber, resulting in a large component. Note that in FIG. 1, 8 is the core of the optical fiber.

Another method uses a patterned optical waveguide as shown in FIG. In this case, each optical fiber of the input/output optical fiber arrays 2, 2' is connected to a mixing optical waveguide 6 for mixing light via an optical branching waveguide 5.
Since the structure is such that the optical fibers are individually coupled within the same leading wave plate 7, there is no excessive loss due to light entering the cladding of the output optical fiber as described in the prior art example.

However, as the number of input/output fibers increases, the mixing waveguide 6 needs to be longer in order to evenly branch the light to the output fibers, as in the conventional example, and the component becomes larger. There is a drawback that excess loss also increases as the total length of the waveguide increases. Another drawback is that when joining an optical fiber array or an optical branching waveguide array, it becomes more difficult to accurately couple individual optical fibers and leading waveguides as the number of input/output fibers increases.

An object of the present invention is to enable an optical branching coupler having a large number of input/output optical fibers to be able to branch light evenly in a small size and with a small excess loss. It is constructed by laminating a plurality of optical coupling waveguide parts of an optical waveguide film in which optical branching and coupling circuits are formed in a film having a magnetic conductivity, and bonding them to both ends of a separately formed thick film mixing waveguide. Features. The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a sectional view of an embodiment of the optical branching coupler according to the present invention, in which the optical waveguide film 7 has a fourth
An optical branching and coupling circuit as shown in the figure, that is, an optical branching waveguide 5 and a mixing waveguide 6 are formed, and a low refractive index layer with a thickness of about several μm is formed on both surfaces. A plurality of these optical waveguide films are formed and bonded together on the side of the coupling optical waveguide 8 so that the optical coupling circuits are properly overlapped, and on the side of the column of optical branching waveguides 5, an optical fiber column 2 is bonded to each side. Fix it. An optical branching/coupling device is constructed by connecting two of the components thus constructed to the input end 9 and the output end 9', respectively, to both end faces of a separately formed mixing plate l. Light incident from any one optical fiber at the input end 9 passes through the coupling waveguide 8 of the branching waveguide 5 in the waveguide film 7, and is evenly split into the mixer 2'. Mixing is also performed in the direction perpendicular to the plate, so in the case of the same number of input and output fibers, the length of the mixing plate is shorter and more uniform compared to the mixing plate of an optical splitter/coupler in which all of the fibers are configured in a plane. You will be able to branch to In Figure 3,
IO is a film support plate, 11 is an optical fiber array support plate MI1
2 is an input end face, and 12' is an output end face.

Further, FIG. 4 is an enlarged plan view of an optical waveguide film in an embodiment of the present invention.

FIG. 5 is a sectional view taken along line A-A' in FIG. 8.

Normally, the core diameter of the optical fiber is approximately 50 to 100/1 m, and the thickness of the optical waveguide film 7 is set to 11 nm, which is the same as the core diameter of the optical fiber. The thickness of the low refractive index layer 13 and the thickness of the adhesive layer 14 are 2 to 5 μm.

Now, for an optical fiber with a core diameter of 80 μm, four layers of optical waveguide film with a thickness of 80 μm are laminated, and the thickness of the gold side of the low refractive index layer 13 and adhesive layer 14 between each optical waveguide layer is 6 pm. Thickness 80 x 4 + 6 x 3 = 844
When the pm mixing plate 1 is bonded, the loss due to light entering the low refractive index layer 13 or adhesive layer 14 of the optical waveguide film 7' at the output end 9' is -1,0,i! Ori(s
447s2o)=o:saB, which is sufficiently small. In FIG. 5, reference numeral 15 indicates a low refractive index portion of the leading wave film.

It is preferable to overlap the optical coupling waveguides 8 with as much accuracy as possible, but even if a slight positional deviation occurs, the width of the optical coupling waveguide is wide, so there is no need to overlay the optical branching coupler due to positional deviation. The loss will not be too large. Now, if a 15-branch optical branching and coupling circuit for a fiber with a core diameter of 80 μm is formed on a single optical waveguide film, the width of the coupling waveguide will be 1.200 μm, and the misalignment of the overlapping position will be less than 7 zm. If this is the case, the increase in loss will be less than 0.3 dB, and the alignment will be very easy.

The flexible optical waveguide film 7 on which the optical branching/coupling circuit of the present invention is formed can be produced by, for example, the method disclosed in Japanese Patent Publication No. 53-2681.3 by the present inventors.
(It can be easily produced.

An optical waveguide film having a waveguide pattern as shown in FIG. 5 produced by this method is formed, and the side to be connected to the optical fiber array is sandwiched between film supporting plates 10, bonded, and the end surfaces are polished. . To this end surface, a T-(, bar row 2 (2'), which is sandwiched between optical fiber row support plates 11 and bonded and whose end surfaces are polished) is bonded and fixed.The branch waveguides 5 are arranged at intervals equal to the outer diameter of the 97-eye fiber. By using closely aligned optical fiber arrays, it is possible to align and connect them all at once.If the number of fibers in a fiber array is up to about 20, variations in the spacing between fiber arrays and waveguide arrays can be avoided. There is little positional deviation due to etc., and rift lt' is possible with small loss of joint JO.
Can be combined with A plurality of optical waveguide films 7 (7') to which fiber arrays 2 (2') are bonded in this way are processed, and they are aligned at the coupling optical waveguide 8.
glue? The C1 input end 9 or the output end 9' is formed by sandwiching and adhering the film support plate 10 and polishing the end face.

Note that the optical branching and coupling circuit as shown in FIG. 2, that is, the central part of the mixing leading waveguide 6 of the optical waveguide film 7 in which the optical branching waveguide 5 and the mixing waveguide 6 are formed with JI≦ is laminated.
By gluing, cutting C, and polishing the cut surfaces, the input end 9 and the output end ' can be formed at the same time.

The mixing plate 1 can be formed in a polymer film in the same manner as the optical waveguide film. Furthermore, since the width and thickness are large, it can be manufactured by processing glass or transparent plastic deck. The end faces 12, 12' of the input end and the output end formed by laminating the optical waveguide film 7 on both end faces of a mixing plate (leading wave plate) made to have a thickness almost equal to the total thickness of the laminated film. An optical branching coupler is obtained by joining the two.

An optical branching coupler that adopts such a configuration and has 60 input and output optical fibers each? , two layers of four f1'# optical waveguide films each having a 15-branch optical branching and coupling circuit each having a length of 25 ili and an optical waveguide film used at the input end and the output end are formed, and an optical fiber is attached to the optical waveguide films. The connected rows were used as input and output terminals, and these were connected to both end surfaces of a mixing plate with a length of 40 mm to create an optical branching coupler.The core diameter was 80 μm, the outer diameter was 1
For 25 μm step-index fiber, insertion loss is 5 dB and distributed power variation is ±0.7 d.
It was B.

As explained above, in the optical branching/coupling device of the present invention, an optical branching/coupling circuit is formed which includes an optical branching waveguide array for input/output and an optical coupling waveguide to be coupled with the input/output optical fiber of the WM. It is constructed by laminating flexible optical waveguide films together with the optical coupling waveguide portion, and bonding the end faces to both ends of the mixing sylate (leading wave plate), so the input and output fibers are Even when the number of fibers increases, the length of the mixing plate is shorter than that of simply arranging all the fibers on a plane.
can be branched, making the components compact, and the loss is small as the length of the mixing plate is shortened.Furthermore, each output core is individually coupled to the mixing plate via a branch waveguide. This has the advantage that there is no loss due to the light entering the cladding of the optical fiber.

[Brief explanation of the drawing]

Fig. 1 is a plan view of a conventional optical branching coupler, Fig. 2 is a plan view of another conventional optical branching coupler, Fig. 3 is a sectional view of an embodiment of the present invention, and Fig. 4 is a plan view of a conventional optical branching coupler. 5 is an enlarged plan view of an optical waveguide film according to an embodiment of the present invention, and FIG. 5 is an enlarged sectional view taken along line A-A' in FIG. DESCRIPTION OF SYMBOLS 1... Mixing plate, 2... Optical fiber row for input, 3... Core of optical fiber, 4I... Clad of optical fiber, 5... Optical branch waveguide, 6... Mixing Optical waveguide, 7... Optical waveguide film, 8... Coupling optical waveguide, 9... Input end, 9'... Output end, lO
... Film support plate <11 ... Optical fiber row support plate, 12 ... Input end end surface, 12' ... Output end end surface, 1
8...Surface low refractive index layer, ■4...Adhesive layer, 15...
・Low refractive index part of optical waveguide film. 1 Ir I l”i21 Figure 2, Figure 3, Figure 4, Figure 6

Claims (1)

[Claims] 1. Input yC: A flexible structure in which an optical branching waveguide array for joining the fiber array and the output nine fiber array and an optical coupling fatigue path for coupling these optical branching waveguide arrays are formed. An optical input end and an optical output end formed by laminating a plurality of optical waveguide films having an optical coupling waveguide part,
An optical branching/coupling device characterized in that it is constructed by bonding each end of an optical waveguide plate having a thickness comparable to that of the entire stack and having a function of equally branching light.