JPH05333229A - 1x2 demultiplexer multiplexer - Google Patents

Abstract

PURPOSE:To eliminate a disturbance by a stop port, to obtain superior packaging performance, and to make nearby crosstalk a little by cutting an unnecessary terminal part and arranging the demultiplexer multiplexer in an outer packaging tube. CONSTITUTION:An optical coupling part 2 formed by fusing and drawing two optical fibers f1 and f2 is fixed to a support base 4 with a proper adhesive. One unnecessary terminal 10 which becomes unnecessary in demultiplexing and multiplexing is cut nearby the support base 4, the cut part is coated with resin 12 having a 1.287-1.657 high refractive index close to that of quartz glass, and the resin part 14 is irradiated with, for example, ultraviolet rays and cured. Then the outer packaging tube 6 like an Invar tube is mounted covering the support base where the optical coupling part 2 is fixed and the cured unnecessary terminal resin coated part and then sealing resin is charged in both end parts of the outer packing tube 6. The demultiplexer multiplexer 1 having 1X2 structure like this has the unnecessary terminal part 14 put in the outer packaging tube 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to an optical coupler used for optical communication, optical measurement, etc.
The present invention relates to a 1 × 2 demultiplexer / multiplexer.

[0002]

2. Description of the Related Art For example, a demultiplexer / multiplexer used in optical communication preferably has a 1 × 2 structure. However, conventionally, 2 × 2
It is used by attaching an antireflection ferrule to an unnecessary terminal of an optical coupler having the above structure.

That is, as shown in FIG. 3, a 2 × 2 optical coupler 1'melts and stretches _two optical fibers f ₁ and f ₂ , and an optical coupling portion 2 formed by this is supported by a support base 4. And a support base 4 to which the optical coupling portion 2 is fixed is covered with an exterior tube 6. Next, in order to form the 1 × 2 demultiplexer-multiplexer 1A, an antireflection ferrule 8 for lowering internal reflection was attached to the end face portion of one terminal which is unnecessary for demultiplexing and multiplexing.

[0004]

[Problems to be Solved by the Invention]
The demultiplexer-multiplexer 1A has a near-end crosstalk (nearest / terminal / crosstalk) of -40 dB or less and is satisfactory in performance, but is unnecessary with the antireflection ferrule 8 attached. The terminal, that is, the stop port is often an obstacle in mounting. For this reason, conventionally, it has been necessary to carry out work for fixing unnecessary terminals when mounting. Further, if the unnecessary terminal is simply cut, the reflection from the cut surface becomes about -14 dB, and the near-end crosstalk becomes about -30 dB, which does not fall below the target of -40 dB.

As a solution to such a problem, the inventor of the present invention has conducted many research and experiments on housing the above-mentioned unnecessary terminal portion in an outer tube. As a result, the unnecessary terminal is cut in the vicinity of the support base, and the cut portion has a refractive index of 1.28 to 1.66 which has a high refractive index, that is, a refractive index close to that of quartz glass. By applying a resin having a ratio, the amount of end face reflection can be reduced to -24 dB or less, and as a result, near-end crosstalk can be reduced to -40 dB or less, and this resin-coated portion can be positioned in the outer tube. Found.

The present invention has been made on the basis of such novel findings.

Therefore, an object of the present invention is that the unnecessary terminal portion does not protrude from the outer tube, so that the stop port does not get in the way, the mountability is excellent, and the near-end crosstalk is- 40 dB or less, 1 × 2
It is to provide a demultiplexer-multiplexer having the structure of.

[0008]

The above object can be achieved by a 1 × 2 demultiplexer-multiplexer according to the present invention. In summary, the present invention has a structure in which an optical coupling part formed by melting and extending two optical fibers is fixed to a support base, and the support base to which the optical coupling part is fixed is covered with an outer tube. A demultiplexing / multiplexing device having a 2 × 2 structure, in which one terminal, which is unnecessary for demultiplexing / multiplexing, is cut close to the support base, and a cutting end face has a refractive index of 1.287 to A 1.times.2 demultiplexer-multiplexer is characterized in that a resin of 1.657 is applied, and the resin-applied portion is located inside the exterior tube. Preferably, the resin is an ultraviolet curable resin, and the near-end crosstalk of the demultiplexer / multiplexer is -40 dB or less.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The 1 × 2 demultiplexer / multiplexer according to the present invention will be described below in more detail with reference to the drawings.

FIG. 1 shows a 1 × 2 demultiplexer-multiplexer 1 according to the present invention.
3 is exaggerated for easy understanding, and its basic structure is the same as that of the conventional 1 × 2 demultiplexer / multiplexer 1A shown in FIG.

That is, the two optical fibers f ₁ and f ₂ are melt-stretched, and the optical coupling portion 2 is fixed to the support base 4 with an appropriate adhesive (not shown) which has been conventionally used. ..

According to the present invention, one unnecessary terminal 10 is
It was cut in the vicinity of the support base 4, and the cut portion had a high refractive index, that is, a refractive index of 1.287 to 1.657, which is close to the refractive index of quartz glass. Resin 12 is applied. As such a resin 12, an ultraviolet curable resin is preferable from the viewpoint of workability until the resin is cured.

If the resin has a refractive index of 1.287 to 1.6.
When the value is out of the range of 57, the demultiplexer-multiplexer 1 obtained when the isolation of the demultiplexer-multiplexer is not 26 dB or more
Is it extremely difficult to reduce the near-end crosstalk of -40 dB or less?
Or it is impossible.

The resin-coated portion 14 is cured by, for example, irradiating it with ultraviolet rays. Then, the optical coupling unit 2
An outer tube 6 such as an Inver tube is attached to cover the support base 4 to which is fixed and the cured unnecessary terminal resin application portion 14. After that, both ends of the outer tube are filled with a sealing resin (not shown).

In the demultiplexer-multiplexer 1 according to the present invention having such a 1 × 2 structure, the unnecessary terminal portion 14 is housed in the outer tube 6, and thus the stop port may be an obstacle. It has excellent mountability. Further, the near-end crosstalk of the obtained demultiplexer-multiplexer 1 is set to -40 dB or less.

Further, an embodiment of the 1 × 2 demultiplexer-multiplexer 1 of the present invention will be described in detail.

Example 1 As the optical fibers f ₁ and f ₂ , the core diameter (d) is 10 μm.
m, the cladding diameter (D) is 125 μm, and a single mode optical fiber is used.
The fiber was pulled in the longitudinal direction of the fiber while being heated to 00 ° C. to carry out the melt drawing process to form the optical coupling part 2. Next, the optical coupling part 2 was fixed to the support base 4 using an adhesive.

Next, one unnecessary terminal 10 is cut in the vicinity of the supporting base 4, and an ultraviolet curable resin (manufactured by Adell Co., Ltd., trade name: Optoclave M01) is cut at this cut end portion.
12 was applied and cured by irradiation with ultraviolet rays.
The refractive index of the ultraviolet curable resin 12 used was 1.52.

After that, the support base 4 to which the optical coupling portion 2 is fixed
Further, the invar tube 6 was attached to cover the cured unnecessary terminal resin application portion 14, and both ends of the tube 6 were filled with a sealing resin.

The near-end crosstalk of the 1 × 2 demultiplexer-multiplexer 1 thus manufactured was measured by the method shown in FIG.

That is, of the manufactured 1 × 2 demultiplexer-multiplexer 1,
In this embodiment, one of the two ports p1 and p2 located on the left side is connected to the light source LD via the connector C16.
Was connected to the other port p2, and an optical measuring instrument PM for measuring reflected light was connected to the other port p2. The light source LD has a wavelength of 1.3.
Using a semiconductor laser that emits light of μm, an optical measuring device P
As M, a light power meter was used.

On the other hand, a non-reflection connector, that is, an oblique ferrule 20 is connected via a connector 18 to one port p3 located on the right side in this embodiment of the 1 × 2 demultiplexer-multiplexer 1.

Each of the connectors 16 and 1 used in this embodiment
8 has a return loss of −40 dB or less,
The slanted ferrule 20 had its end face polished to 8 ° or 12 °, and its reflection attenuation amount was −70 dB or less.

With this configuration, when the light source LD is turned on and a predetermined amount of light (P ₁ [mW]) of 0 dBm, 1.3 μm, is incident on the port p1, the light is emitted on the port p.
It is output to 3 as light of -0.5 dBm or less. The light from the output port p3 is reflected at the connection point of the connector 18, returns to the demultiplexer-multiplexer 1 as light of -40.5 dBm or less, and enters the port p1 as light of -41.0 dBm. Further, the light of -56.5 dBm is output to the port p2. The reflected light output to the port p2 is detected by the optical measuring device PM connected to the port p2, and the light amount (P _2-1 [mW]) is measured.

The 1.3 .mu.m light input to the port p1 is also output to the unnecessary terminal portion 10 of the demultiplexer-multiplexer 1 with a predetermined branching ratio. This light is Fresnel-reflected at the cut end face of this end portion, becomes return light, enters the demultiplexer-multiplexer 1, and is output to the ports p1 and p2. The reflected light to the port p2 is the optical measuring instrument P connected to the port p2.
The amount of light (P _2-2 [mW]) is detected by M and measured.

"Near-end crosstalk" in the present invention is defined by the following equation. Near-end crosstalk = −10 × log {(P _2-1 + P _2-2 ) / P
₁ ) The near-end crosstalk of the 1 × 2 demultiplexer-multiplexer 1 constructed according to the present invention is −46.881 to −59.86 dB, and always −
It was 40 dB or less, and it was possible to obtain the same level of performance as the near-end crosstalk of the currently available 1 × 2 demultiplexer-multiplexer 1A having the structure shown in FIG.

[0027]

EFFECT OF THE INVENTION 1 according to the present invention configured as described above
In the × 2 demultiplexer-multiplexer, one unnecessary terminal is cut close to the support base, and the cut portion is coated with resin and then placed inside the outer tube, so that the unnecessary terminal portion is cut off from the outer tube. Therefore, the stop port does not get out of the way, the mountability is extremely excellent, and the near-end crosstalk is -40 dB or less.

[Brief description of drawings]

FIG. 1 is a schematic configuration sectional view showing an embodiment of a 1 × 2 demultiplexer-multiplexer according to the present invention.

FIG. 2 is a configuration diagram for explaining a method for measuring near-end crosstalk of a 1 × 2 demultiplexer-multiplexer according to the present invention.

FIG. 3 is a schematic configuration sectional view showing a conventional 1 × 2 demultiplexer-multiplexer.

[Explanation of symbols]

 1 1 × 2 demultiplexer-multiplexer 2 optical coupling section 4 support stand 6 exterior tube 10 unnecessary terminal section 12 resin

Claims (2)

[Claims] 1. A 2 × 2 structure in which an optical coupling part formed by melting and extending two optical fibers is fixed to a support base, and the support base to which the optical coupling part is fixed is covered with an outer tube.
In the demultiplexer-multiplexer having the structure of, one terminal that is not needed for demultiplexing-multiplexing, is cut close to the support base,
A resin having a refractive index of 1.28 to 1.66 is applied to the cut end face portion, and the resin-applied portion is positioned inside the exterior tube. vessel. 2. The resin according to claim 1, wherein the resin is an ultraviolet curable resin, and the near-end crosstalk of the demultiplexer-multiplexer is -40 dB or less.
× 2 demultiplexer / multiplexer.