JP2002031722A - Method for partial metallization of optical fiber top end - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for partial metallization of the top end of an optical fiber by which a metal layer of designed length can be formed on a coated fiber. SOLUTION: The method for metallization of the top end of an optical fiber includes a process of wholly coating the top end of the raw fiber 1b where the coating member 1a is removed, so as to form a metal layer 2 and a process of dipping the top end in an etchant 3 which dissolves the metal layer 2. By controlling the dipping depth (d) of the top end, the metal layer 2 in specified length (L1) is left in the region not dipped of the top end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for partially metallizing an optical fiber tip, and more particularly, to an optical fiber tip capable of accurately forming a metal layer having a designed length on the optical fiber tip. Partial metallization method.

[0002]

2. Description of the Related Art For example, in an optical module using a semiconductor laser device as a light source, the semiconductor laser device is fixed to a coupling support positioned and positioned in an airtight housing.
On the oscillation surface, the coating member of the optical fiber is stripped and removed to expose a predetermined length, and the distal end of the fiber core wire, the tip of which is a spherical lens, is arranged to be opposed. .

In this case, the light source and the fiber core are aligned with each other so that the optical coupling efficiency between the light source and the fiber core is maximized. Specifically, the optical axis of the light source and the fiber core are aligned, and the distance between the spherical end of the fiber core and the oscillation surface of the light source is optimized. The wires are fixed to the coupling support.

Heretofore, generally, the above-mentioned fixing of the fiber core to the coupling support is generally performed by using a ferrule. Specifically, for example, a fiber core is inserted into the through-hole of a ferrule having a through-hole at the center, which is made of Kovar, and the paste between the fiber core and the ferrule is made of, for example, Au powder and Sn powder, Au-Sn
The ferrule is hermetically fixed with a sealing material such as an alloy or Sn-Pb solder, and the ferrule in that state is similarly fixed to the bonding support with the sealing material. In other words, the fiber core is indirectly fixed to the coupling support via the ferrule.

[0005] However, recently, the coated fiber is stripped and removed, and the bare fiber is covered with a metal layer, and the fiber is positioned on a connection support with a light source, and then the metal layer is bonded. It has been practiced to fix the fiber ribbon directly to the coupling support by heat-sealing the support to the support. This is because the number of components to be used is smaller than in the case of fixing using a ferrule, and the work of arranging the sealing material is not required, so that the cost as a whole can be reduced.

Here, an optical fiber directly fixed to the coupling support base is used.
One example of fiber is shown in FIG. This optical fiber is coated
The member 1a is peeled and removed, and the tip of the member 1a has a design standard length.
(L ₀)), The fiber core 1b is uncovered.
Processed into spherical tip, coated out of fiber core 1b
The part on the member 1a side has a length (L₁) Covered with metal layer 2
And the rest remains bare fiber core.
I have. This metal layer 2 is usually formed by electroless plating and electrolytic plating.
It is formed by combining.

[0007] Then, the above-mentioned metal layer 2 is thermally fused to the coupling support, and the fiber core 1b, that is, the entire optical fiber is fixed to the coupling support.

[0008]

When the type of the optical module to be assembled and the type of the coupling support used for the module are changed, the total length (L ₀ ) of the fiber core 1 b and the length of the metal layer 2 are changed accordingly. It is necessary to change (L ₁ ). In that case, forming the length (L ₀ ) of the fiber core wire 1b according to the design reference value can be easily realized by designing the peel length of the coating member 1a to that value.

However, it is extremely difficult to form the length (L ₁ ) of the metal layer 2 in accordance with the design standard value because the metal layer 2 is generally formed by plating. For example, when a metal layer 2 having a length (L ₁ ) is formed on the surface of a fiber core by a plating method, a portion of the fiber core other than the metal layer is masked using a plating resist or the like and plated. Is performed so that a metal layer having a length (L ₁ ) can be formed.

However, as a practical problem, since a foreign material such as a silicone-based coupling agent is present on the surface of the bare fiber core 1b after the coating member 1a is peeled off and removed, plating is not possible. An operation for removing these foreign materials is required beforehand. Specifically, the surface of the fiber core 1b is cleaned by immersing it in hot sulfuric acid at a temperature of about 70 to 90 ° C. or a hot alkaline aqueous solution at a temperature of about 70 to 90 ° C. to remove foreign materials.

Therefore, in the above-mentioned surface cleaning treatment prior to the plating, the above-mentioned dissolution of the masking or the like occurs. As a result, in the plating process, the masked portion of the fiber core wire is also irregularly plated. . That is, it is difficult to partially and accurately form the metal layer 2 having the design reference value only in the length of the design purpose (L ₁ ), even if the above-described masking method is applied.

The present invention solves the above-mentioned problem when a metal layer is partially formed at the tip of a fiber core, and can accurately form a metal layer having a design reference length. It is an object of the present invention to provide a method for partially metallizing a fiber tip.

[0013]

In order to achieve the above object, in the present invention, there is provided a step of forming a metal layer by covering the entire surface of the distal end of a fiber core stripped out by removing a coating member. Comprises a step of immersing the tip in an etchant that dissolves the metal layer, by adjusting the immersion depth of the tip, the unimmersed region of the tip, the metal of a predetermined length A method for partial metallization of an optical fiber tip is provided, wherein the layer is left.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described below in detail. First, the coated member of the optical fiber is peeled off, and the length (L ₀ ) of the optical fiber is exposed. Since a coupling agent or the like is present on the surface of the fiber core wire, a surface cleaning process is performed to remove the same.

More specifically, the temperature of the fiber core is changed to 7 ° C.
It is preferable to immerse in hot sulfuric acid at 0 to 90 ° C. for about 10 minutes, take out and wash with water, and then immerse in hot potassium hydroxide solution at a temperature of 70 to 90 ° C. for about 10 minutes, take out and wash with water. Next, the surface of the cleaned fiber core 1b is subjected to electroless plating to impart surface conductivity, and further subjected to electroless plating or electrolytic plating to cover the entire surface of the fiber core, for example, a two-layer metal. The layer 2 is formed (FIG. 2).

Although the electroless plating and the electrolytic plating are not particularly limited, examples of the electroless plating include N
The electroless plating and the electrolytic plating of i are preferably Au electrolytic plating. Next, as shown in FIG. 3, the tip of the fiber is immersed in the etchant 3.

The immersion depth (d) at this time is (L ₀ ) when the length of the metal layer formed on the fiber core is L _1.
−L ₁ ). At this time, an etchant that dissolves only the metal layer 2 formed on the fiber core wire 1b is used. This dipping process, portions of the metal layer is immersed in an etchant 3 is dissolved and removed, there length (L ₀ -L ₁₎ surface portion of the fiber 1b is the exposed, also not immersion region not immersed in an etchant 3 is left on the fiber as a metal layer of a length L _1, wherein the distal end of the fiber shown in FIG. 1 is formed.

As described above, the metal layer 2 is usually
This immersion treatment is performed twice because of the two-layer structure. That is, the plating component (electrolytic plating component) forming the upper layer of the metal layer 2 is dissolved in the first immersion treatment. Then, it is immersed in another etchant to dissolve and remove the base component (electroless plating component) of the metal layer 2 to finally expose the surface of the fiber core.

For example, if the metal layer 2 is composed of Ni as the base component and Au as the upper layer component, the first immersion treatment removes Au on the surface with, for example, a commercially available gold release agent.
In the second immersion treatment, for example, ferric chloride or nitric acid is preferably used as an etchant.

[0020]

EXAMPLE A coated member of an optical fiber having a fiber core diameter of 125 μm was peeled off and removed to obtain a length (L ₀ ) of 50 m.
The fiber core was stripped over m. After aligning the optical fiber on one jig in a state where the leading end of the fiber core is aligned, the whole is fixed, and the fiber core portion is initially heated with hot sulfuric acid (temperature: 70 to 80 ° C.) (Concentration 50%)
After immersion in water for 10 minutes, remove and wash with water,
1% aqueous potassium hydroxide solution (concentration 100g / l) at 0 ° C
After immersion for 0 minutes, it was taken out and washed with water.

Next, the tip of the fiber core was treated with a sensitized aqueous solution (room temperature) prepared by dissolving 0.5 g / l of stannous chloride in pure water, and an activated aqueous solution of 0.1 g / l palladium chloride (room temperature). ), Then liquid composition: ammonium sulfate 2
0 g / l, ammonium acetate 20 g / l, sodium hypophosphite 30 g / l, nickel sulfate 25 g / l, dipped in an electroless plating solution (room temperature), and electroless N having a thickness of 1 to 5 μm.
An i-layer was formed.

Then, it was immersed in an electroless Au plating solution of 2 g / L of potassium cyanide (temperature 90 ° C., pH 7) for 5 minutes,
Electroless Au having a thickness of 0.1 to 0.2 μm on the electroless Ni layer
The layers were deposited to produce the fiber core shown in FIG.
Next, with the tip of the optical fiber kept aligned, the tip of the fiber was first immersed in an etchant of a commercially available gold release agent (room temperature) for 3 minutes, then taken out and washed with water. Subsequently, the substrate was immersed in an etchant of sulfuric acid (a ratio of pure water to 1: 1, room temperature) for 3 minutes, taken out, and washed with water.

At this time, the immersion depth (d) of the tip in the aligned state was controlled to be 30 ± 2 mm. That is, the length (L ₁ ) of the remaining plating layer is 20 ±
It was controlled to be 2 mm. The optical fiber after the treatment was removed from the jig, and the state of the plating layer at the end of each fiber core was examined. In each case, as shown in FIG. 1, the plating layer 2 was formed only on the base of the fiber core wire 1b, and the length was 20 ± 2 mm.

[0024]

As apparent from the above description, the present invention has the following effects. (1) First, the length (L ₁ ) of the metal layer to be designed can be accurately realized only by immersing the tip of the fiber core in the etchant. Therefore, by changing the immersion depth (d) at the tip, various optical fibers having the metal layer length required for various optical modules can be easily manufactured.

(2) The present invention can be implemented by aligning the tip of the optical fiber to be processed on a jig and immersing it in an etchant. Partial metallization of the desired optical fiber can be realized.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing an example of an optical fiber manufactured by the method of the present invention.

FIG. 2 is a partial cross-sectional view showing a state where a metal layer is formed on the entire fiber core.

FIG. 3 is a schematic view showing a state in which the tip of the fiber core is immersed in an etchant.

[Explanation of symbols]

 1a Coating member 1b Fiber core 2 Metal layer 3 Etchant

Claims (2)

[Claims] A step of forming a metal layer by covering the entire surface of the distal end portion of the fiber ribbon exposed by removing the coating member;
A step of immersing the tip in an etchant that dissolves the metal layer, and by adjusting the immersion depth of the tip, a non-immersed region of the tip has a predetermined length of the metal layer. A method of partially metallizing the tip of an optical fiber, characterized by leaving 2. The optical fiber according to claim 1, wherein a coupling agent attached to the distal end of the fiber is removed before forming a metal layer on the entire surface of the distal end of the fiber. Partial metallization method.