JP3714337B2 - Optical connector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical connector used when optical components are optically connected.
[0002]
[Prior art]
In order to optically connect an optical fiber core to an optical component, it is common to attach an optical connector to the end of the optical fiber core and optically connect via this optical connector. The outer diameter of the optical fiber is about 0.125 mm, and the connection loss will increase unless the core at the center is accurately positioned. Therefore, the optical connector and the mating optical component must be positioned with very high accuracy. There is. For this reason, a guide pin fitting type optical connector in which the optical connector and the counterpart optical component are positioned by a guide pin is generally used. On the optical connection surface of the optical connector of the guide pin fitting type, an end portion of the optical fiber is disposed and a pair of pin insertion holes for inserting the guide pins are opened, and the guide pins are inserted. On the other hand, an optical fiber, an end of an optical waveguide, an optical element, and the like are also arranged on the optical connection surface of the counterpart optical component, and a pair of pin insertion holes for inserting guide pins are opened. Yes. By inserting the protruded guide pin into the guide pin insertion hole of the counterpart optical component, the end face of the optical fiber arranged on the optical connection surface of the optical connector, the end face of the optical fiber of the counterpart optical component, the optical waveguide, and the optical element Etc. are accurately positioned. This type of optical connector is used for optical connection in a place where branching or switching is required in an optical communication line. In order to switch the connection, it is necessary to attach and detach the optical connector. Therefore, the optical connector is required to have a small connection loss fluctuation even if the optical connector is repeatedly attached and detached.
[0003]
[Problems to be solved by the invention]
As described above, the optical connector and the optical component are positioned with high accuracy via the guide pins. For this reason, when the optical connector is repeatedly attached and detached, the pin insertion hole of the mating optical component may be worn by friction between the guide pin of the optical connector and the pin insertion hole of the mating optical component, or the opening edge of the pin insertion hole May be lost, and the connection loss increases. Therefore, the present invention reduces the friction between the guide pin of the optical connector and the pin insertion hole of the counterpart optical component, and even if the attachment and detachment is repeated, the wear and damage of the pin insertion hole of the counterpart optical component are unlikely to occur. It is an object of the present invention to provide an optical connector in which loss is unlikely to increase.
[0004]
[Means for Solving the Problems]
The optical connector according to claim 1 includes a ferrule having a pair of pin insertion holes for positioning with at least one fiber array hole for accommodating an optical fiber and a counterpart optical component, and a pair of pins inserted into the pin insertion holes. A guide pin is made of stainless steel, a base layer mainly composed of chromium is formed on the surface thereof, and a surface film layer mainly composed of gold is formed on the surface of the base layer. It is said.
[0005]
According to a second aspect of the present invention, in the optical connector according to the first aspect of the present invention, the thickness of the underlayer mainly composed of chromium is 1500 to 10,000 angstroms .
[0007]
According to a third aspect of the present invention, in the optical connector according to the first or second aspect , the ferrule is mainly composed of a thermoplastic resin.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of an optical connector of the present invention will be described with reference to the drawings. First, a first embodiment of the optical connector of the present invention is shown in FIG.
[0011]
As shown in FIG. 1, the optical connector 1 of the present embodiment is a so-called MPO connector, and a ferrule 2 that abuts against a counterpart optical component and a guide pin 10 for accurately positioning the counterpart optical component. And have. Such MPO connectors are detachably connected via the adapter 4.
[0012]
The ferrule 2 is made of a PPS resin that is a thermoplastic resin. On one end side of the ferrule 2, an optical connection surface 5 that comes into contact with the counterpart optical component is formed. The ferrule 2 has eight parallel fiber array holes 6 that house the tip ends of the optical fibers in the optical fiber core wire 3, and one end of each of them is substantially at the center of the optical connection surface 5. Is open.
[0013]
Each guide pin 10 has a surface coating layer mainly composed of gold formed by sputtering on its surface. Specifically, each guide pin is ultrasonically cleaned with alcohol, acetone, or pure water to remove oil and the like on the surface of the guide pin. Thereafter, in order to improve the adhesion of the gold film, a chromium film is formed by sputtering on the surface of the guide pin as a base treatment. Further, a surface coating layer containing gold as a main component is formed thereon by sputtering. In this case, the film thickness of the chromium film is desirably 1500 to 10000 angstroms, and particularly desirably 1500 to 5000 angstroms. The thickness of the gold film is preferably 1000 to 10,000 angstroms. The sputtering rate is 100 angstroms per minute for the chromium film and 150 angstroms per minute for the gold film, and is formed in a porous state.
[0014]
Moreover, the front-end | tip part of each guide pin 10 is formed in the taper shape, and is easy to insert with respect to the pin insertion hole of the other party optical component. Since the guide pin 10 is used as a positioning pin, stainless steel is most suitable from the viewpoint of processing accuracy and rigidity. If gold is coated directly on the stainless steel surface, sufficient adhesion strength of the film cannot be ensured. Therefore, the base treatment is usually performed by coating with chromium or nickel. In the case of a stainless steel guide pin, the strongest adhesive strength can be obtained when chromium is used for coating. The thickness of the chrome film is convenient to ensure dimensional accuracy, but if it is too thin, the coating layer strength cannot be sufficiently secured (the strength of the chrome film itself cannot be secured, and the adhesive strength can be secured). In addition, the strength of the gold film cannot be secured).
[0015]
Considering these things, the thickness of the chromium film is preferably 500 to 10,000 angstrom as described above. If it is less than 500 angstroms, the chromium film is too thin to ensure sufficient strength. On the other hand, if it seems to exceed 10,000 angstroms, it becomes difficult to ensure sufficient dimensional accuracy. The thickness of the gold film is preferably 1000 to 10,000 angstroms. If the thickness of the gold film is less than 1000 angstroms, sufficient strength as a film cannot be secured. Further, if the thickness of the gold film exceeds 10,000 angstroms, it becomes difficult to ensure sufficient dimensional accuracy.
[0016]
Since gold has physical properties with low frictional resistance, the friction coefficient between the guide pin 10 and the pin insertion hole of the counterpart optical component is reduced by forming a surface coating layer on the surface of the guide pin mainly composed of gold. Can do. For this reason, it is possible to reduce the friction between the guide pin and the pin insertion hole of the counterpart optical component by forming a surface coating layer mainly composed of gold. As a result, even if the attachment / detachment is repeated, the pin insertion hole of the counterpart optical component is hardly worn or damaged, and an increase in connection loss can be avoided. In the case of a surface coating layer containing gold as a main component, the friction coefficient between the guide pin and the pin insertion hole of the counterpart optical component is reduced from one-third to one-tenth when there is no surface coating layer. Wear or damage to the pin insertion hole of the counterpart optical component is less likely to occur. Furthermore, since the surface coating layer containing gold as a main component has a low Young's modulus, the optical connector can be attached and detached stably and stably without being peeled off by an impact at the time of attachment and detachment by being somewhat elastically deformed.
[0017]
Among optical connectors, in the case of an ultra-low loss type multi-fiber optical connector that achieves a maximum loss of 0.35 dB or less, a pin insertion hole for inserting a guide pin and a guide pin to increase positioning accuracy during connection Is set to 0.3 μm or less. In such an optical connector having a very narrow clearance, the stress on the film during attachment / detachment becomes large, so even if the thickness of the chromium film is within the above-mentioned range, a strength viewpoint is considered. For example, about 3000 to 10000 angstroms is the most desirable region. That is, considering the balance between strength and dimensional accuracy, it is more preferably 1500 to 5000 angstroms.
[0018]
FIG. 2A shows the result of a detachment test using a conventional optical connector that does not have a surface coating layer mainly composed of gold. FIG. 2 (b) shows the result of an attachment / detachment test using an optical connector having a surface coating layer formed by gold vapor deposition. The connector shown in FIG. 1 is an eight-core MPO connector having a surface coating layer formed by gold sputtering on the guide pin 10, but the 8-pin MPO connector having a gold surface coating layer formed by sputtering on the guide pin is used. MPO connector. The test was performed by measuring the optical loss fluctuations of the first and third optical fibers after the optical connector was repeatedly attached and detached. As shown in FIG. 2 (a), the optical loss increases as the number of attachments and detachments increases in the conventional MPO connector. However, as shown in FIG. 2 (b), the MPO having a guide pin having a surface coating layer formed by sputtering. With a connector, optical loss does not increase even if the number of attachments / detachments increases.
[0019]
In the formation of the gold surface coating layer by the sputtering method, since the sputtering rate can be easily changed, the film thickness can be managed with high accuracy (with an accuracy of 100 angstroms or less). Further, since a thin film having a film thickness of 1000 to 10000 angstroms can be formed and the film thickness can be controlled with high accuracy, the outer diameter of the guide pin can be controlled with high accuracy. As a result, the optical connector and the counterpart optical component can be positioned with high accuracy, and the connection loss can be further reduced.
[0020]
In the optical connector 1 of the first embodiment described above, a sputtering method is used as a method for forming a surface coating layer mainly composed of gold on the surface of the guide pin. As described above, the sputter method is preferable because the dimensional accuracy of the guide pin outer diameter can be controlled with high accuracy, but the guide pin and the counterpart optical component can be formed even if a surface coating layer mainly composed of gold is formed by vapor deposition or plating. Since the friction of the pin insertion hole can be reduced, the effect of suppressing wear and damage of the pin insertion hole of the counterpart optical component can be obtained.
[0021]
Next, a second embodiment of the optical connector of the present invention will be described. Since the configuration of the optical connector of the present embodiment is the same as that of the first embodiment, the same or equivalent components are denoted by the same reference numerals, and detailed description thereof is omitted. Each guide pin 10 has a surface coating layer whose main component is a fluorine-based metal surface treatment agent. The surface coating layer is formed on the surface of the guide pin by electroless plating or coating. The fluorine-based metal surface treating agent is a polymer compound containing fluorine used for coating a metal surface. The fluorine-based metal surface treatment agent includes a fluororesin. The fluororesin includes PTFE, PFA, FEP, EPE, ETFE, PCTFE, PVDF, PVF and the like.
[0022]
Since the fluorine-based metal surface treatment agent has physical properties with low frictional resistance, the guide pin 10 and the counterpart optical component are formed by forming a surface coating layer on the surface of the guide pin mainly composed of the fluorine-based metal surface treatment agent. The coefficient of friction of the pin insertion hole can be reduced. For this reason, the friction between the guide pin and the pin insertion hole of the counterpart optical component can be reduced by forming the surface coating layer mainly composed of the fluorine-based metal surface treatment agent. As a result, even if the attachment / detachment is repeated, the pin insertion hole of the counterpart optical component is hardly worn or damaged, and an increase in connection loss can be avoided. In addition, if the surface coating layer is a guide pin surface mainly composed of a fluorine-based metal surface treatment agent, the friction coefficient between the guide pin and the pin insertion hole of the counterpart optical component is one-third that when there is no surface coating layer. It becomes small to 1/10. Wear or damage to the pin insertion hole of the counterpart optical component is less likely to occur. Further, the surface coating layer mainly composed of a fluorine-based metal surface treatment agent is well fixed on the metal surface, and can be stably and repeatedly attached and detached without being peeled off by an impact during attachment and detachment.
[0023]
By forming the surface coating layer of the fluorine-based metal surface treatment agent by electroless plating, it is possible to form a thin film with a comma of several μm, and the film thickness can be controlled with high precision. The outer diameter can be controlled with high accuracy. As a result, the optical connector and the counterpart optical component can be positioned with high accuracy, and the connection loss can be further reduced.
[0024]
Next, a third embodiment of the optical connector of the present invention will be described. Since the configuration of the optical connector of the present embodiment is the same as that of the first embodiment, the same or equivalent components are denoted by the same reference numerals, and detailed description thereof is omitted. Each guide pin 10 has a surface coating layer mainly composed of DLC on the surface. The surface coating layer is formed by a high frequency plasma CVD method. DLC is diamond-like hard carbon, and has characteristics such as high hardness, low wear, low friction, and excellent surface smoothness, and is also used as a coating agent for molds, tools, sliding parts, and the like.
[0025]
Since DLC has physical properties with low frictional resistance, the friction coefficient between the guide pin 10 and the pin insertion hole of the counterpart optical component is reduced by forming a surface coating layer on the surface of the guide pin mainly composed of DLC. Can do. For this reason, the friction of the guide pin and the pin insertion hole of the counterpart optical component can be reduced by forming the surface coating layer mainly composed of DLC. As a result, even if the attachment / detachment is repeated, the pin insertion hole of the counterpart optical component is hardly worn or damaged, and an increase in connection loss can be avoided. Further, if the surface coating layer on the surface of the guide pin mainly composed of DLC, the friction coefficient between the guide pin and the pin insertion hole of the counterpart optical component is 1/3 to 1/10 of the case without the surface coating layer ( Without friction, the friction coefficient is reduced to 0.05 to 0.2). Wear or damage to the pin insertion hole of the counterpart optical component is less likely to occur. Furthermore, since the surface coating layer mainly composed of DLC has excellent wear resistance and high adhesion to the substrate, the optical connector can be stably attached and detached repeatedly without being peeled off due to impact during attachment and detachment. .
[0026]
The DLC processing by the high-frequency plasma CVD method is suitable for processing precision parts such as guide pins because uniform film formation is possible by repeating ON / OFF of the applied high-frequency power in a short cycle. In addition, since a thin film having a comma number of μm can be formed and the film thickness can be controlled with high accuracy, the outer diameter of the guide pin can be controlled with high accuracy. As a result, the optical connector and the counterpart optical component can be positioned with high accuracy, and the connection loss can be further reduced.
[0027]
In the optical connector 1 of the third embodiment described above, the high frequency plasma CVD method is used as a method for forming the surface coating layer mainly composed of DLC on the surface of the guide pin. However, DLC is mainly composed by ionization vapor deposition or PVD. Even if the surface coating layer to be formed is formed, the friction between the guide pin and the pin insertion hole of the counterpart optical component can be similarly reduced, so that the effect of suppressing wear and damage of the pin insertion hole of the counterpart optical component can be obtained.
[0028]
The ferrule 2 in the first to third embodiments described above is formed of PPS which is a thermoplastic resin. The above-described guide pin having a surface coating layer capable of reducing friction is preferably combined with a ferrule formed of PPS which is such a thermoplastic resin.
[0029]
Since the ferrule 2 of the optical connector 1 is formed of a thermoplastic resin, the ferrule 2 is easily elastically deformed. As a result, the possibility that the pin insertion hole is worn or damaged when the optical connector is attached / detached is reduced, so that connection loss due to repeated attachment / detachment can be further reduced.
[0030]
From this viewpoint, the Young's modulus of the thermoplastic resin forming the ferrule 2 is preferably in the range of 13 GPa to 30 GPa. If the Young's modulus is less than 13 GPa, the material is plastically deformed to deteriorate the optical characteristics, which is not preferable. If the Young's modulus is more than 30 GPa, the material becomes brittle and easily breaks, which affects the optical properties, which is not preferable.
[0031]
Furthermore, it is preferable that the friction coefficient between the guide pin 10 of the optical connector of the first to third embodiments described above and the counterpart optical component is in the range of 0.01 to 0.2. If the friction coefficient exceeds 0.2, the effect of suppressing wear and damage of the pin insertion hole of the counterpart optical component is reduced, which is not preferable.
[0032]
The optical connector according to the embodiment of the present invention is not limited to the above-described embodiment. The optical connector of the present invention may be an optical connector with guide pins of another shape such as an MT connector instead of an MPO connector. As optical connectors, MT connectors, FC connectors, SF connectors, SSF connectors, MF connectors, premises FO connectors, SC connectors, D connectors, MF connectors, and the like are known.
[0033]
【The invention's effect】
According to the first to third aspects of the present invention, by reducing the friction coefficient between the guide pin and the pin insertion hole of the counterpart optical component, the influence of wear and damage on the pin insertion hole due to friction can be reduced, and the optical connector can be attached and detached. The connection loss due to repeating the above can be kept low. Therefore, it is possible to provide an optical connector with little fluctuation in connection loss even after repeated attachment and detachment, and a ferrule and an optical connector for this optical connector.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an optical connector of the present invention.
FIGS. 2A and 2B are graphs showing loss fluctuations due to repeated attachment and detachment, wherein FIG. 2A shows the result of the conventional product, and FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical connector, 2 ... Ferrule, 3 ... Optical fiber core wire, 4 ... Adapter, 5 ... Optical connection surface, 6 ... Fiber arrangement hole, 10 ... Guide pin.

Claims (3)

A ferrule having a pair of pin insertion holes for positioning with at least one fiber array hole for accommodating an optical fiber and a counterpart optical component, and a pair of guide pins inserted into the pin insertion holes,
An optical connector, wherein the guide pin is made of stainless steel, a base layer mainly composed of chromium is formed on a surface thereof, and a surface film layer mainly composed of gold is formed on the surface of the base layer . 2. The optical connector according to claim 1, wherein a thickness of the base layer containing chromium as a main component is 1500 to 10,000 angstroms. The optical connector according to claim 1, wherein the ferrule contains a thermoplastic resin as a main component.

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