JP3592384B2 - Polishing method of optical fiber connector - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for polishing an optical fiber connector, particularly an MT connector (see below).
[0002]
[Prior art]
First, an MT (Mechanically Transferable) connector will be briefly described.
FIG. 3 schematically shows a state before assembly. (A) is a perspective view of one ferrule, (b) is a plan view, and (c) is a side view.
Reference numeral 20 denotes the entire ferrule. The main body 22 is made of a precision molded product such as an epoxy resin having good dimensional stability and high mechanical strength (see Fujikura Technical Report No. 84, pp. 58-63).
Guide holes 24 for positioning are provided at both ends of the main body 22 (for the guide pins 30). An optical fiber hole is provided at a predetermined position on a reference line connecting the centers of both guide holes 24. Then, the optical fiber 12 of the optical fiber ribbon 10 is passed through the hole and fixed with an adhesive.
After attaching the optical fiber ribbon 10, the end face of the ferrule 20 is polished with a polishing plate of 6 μm or less.
[0003]
Upon connection, a guide pin 30 for positioning is inserted into the guide hole 24 of one ferrule 20, butted against the other ferrule 20, and the tip of the guide pin 30 is inserted into the guide hole 24 of the other ferrule 20. Thus, the end faces of both optical fibers are accurately butted.
Then, as shown in FIG. 4, a constant pressing force is applied in the axial direction of the optical fiber by the clamp spring 32 to secure a stable connection state.
[0004]
[Problems to be solved by the invention]
As shown in FIG. 5A, the guide hole 24 may be lined with a ceramic sleeve 26 (the ceramic sleeve 26 is insert-molded on the inner surface of the guide hole 24). This is performed in order to improve the abrasion resistance against the insertion and removal of the guide pin, the dimensional stability, and the like.
When the end face of the ferrule 20 thus formed is polished as in the prior art as shown in FIG.
Since the hardness of the ceramic sleeve 26 is higher than that of the plastic body 22, the end protrudes slightly from the end face of the body 22 as shown in FIG.
Then, the following problem occurs.
{Circle around (1)} When the connector is connected, the end face of the optical fiber 12 is brought into a non-contact state, and the connection loss increases.
{Circle around (2)} The temperature dependence of connection loss increases.
[0005]
[Means for Solving the Problems]
At the time of polishing, the height of the front surface of the ferrule 20 and the height of the tip position of the ceramic sleeve 26 are made different. For this purpose, the ferrule 20 is polished in a cooled state.
[0006]
Alternatively, the polishing is performed in a state where the temperature of the ceramic sleeve 26 is higher than the other portions.
[0007]
[Operation]
The linear expansion coefficient of plastic is larger than that of ceramics. Thus, upon cooling, the plastic ferrule body shrinks more than the ceramic sleeve. Therefore, the ceramic sleeve protrudes from the end face of the ferrule main body (when molding is completed, the end face of the ceramic sleeve coincides with the end face of the ferrule main body).
Polishing in this state, as a result, even if the ceramic sleeve is projected from the end face of the ferrule main body 22 as described above,
When returned to room temperature, the ferrule body recovers more length than the ceramic sleeve.
Therefore, by appropriately selecting the cooling temperature with respect to the linear expansion coefficient of the ferrule body and the ceramic sleeve, it is possible to prevent the ceramic sleeve from projecting from the end face of the ferrule at normal temperature.
[0008]
When the temperature of the ceramic sleeve is set to be higher than that of other parts, the ceramic sleeve expands and its end protrudes from the end face of the ferrule main body.
Therefore, in the same manner as described above, polishing is performed in this state, and as a result, even if the ceramic sleeve projects from the end face of the ferrule main body as described above,
When returned to room temperature, the ceramic sleeve shrinks.
Therefore, by making the heating temperature of the ceramic sleeve appropriate for the linear expansion coefficient of the ferrule body and the ceramic sleeve, it is possible to prevent the ceramic sleeve from projecting from the end face of the ferrule at normal temperature.
[0009]
Embodiment 1
The ferrule 20 was polished in a cooled state in a thermostat 36 as shown in FIG.
The material of the main body 22 is, for example, an epoxy resin containing a glass filament (linear expansion coefficient is approximately 1.5 × 10 ⁻⁵ / ° C.), and the material of the ceramic sleeve 26 is, for example, zirconia ceramics (linear expansion coefficient is approximately 0.9). a x10 ^-5 / ℃).
Although no particular numerical value is given for the hardness, it goes without saying that ceramics is harder than plastic.
The end face of the ferrule 20 was flat-polished by a 6 μm polishing plate 34 in a thermostat 36 kept at 4 ° C.
Thereafter, when the ferrule 20 was taken out of the thermostat bath 36 and returned to normal temperature (FIG. 9B), there was no protrusion of the ceramic sleeve 26 at the end face of the ferrule 20.
[0010]
The ferrule 20 may be polished without using the constant temperature bath 36 during polishing, for example, while applying a large amount of cold water at 0 to 4 ° C.
[0011]
Embodiment 2
As shown in FIG. 2, a metal pin 38 having good thermal conductivity was inserted into the ceramic sleeve 26 and heated by the heater 40 in order to polish the ceramic sleeve in a state where the temperature of the ceramic sleeve was higher than other portions. .
When the main body 22 and the ceramic sleeve 26 are the same as in the first embodiment (the inner diameter of the ceramic sleeve 26 is about 0.7 mm), the pin 38 is made of copper having an outer diameter of about 0.6 mm. The end face of the ferrule 20 was flat-polished while being heated to about 60 to 80 ° C.
Thereafter, when the pins 38 were removed and the ceramic sleeve 26 was returned to room temperature, no protrusion of the ceramic sleeve 26 from the ferrule end face was observed.
[0012]
As an example of the present invention, the ferrule is made of plastic and the sleeve is made of ceramic. However, the method of the present invention is applied to polishing of various composite surfaces having different physical coefficients (particularly, thermal expansion coefficient and hardness). it can.
[0013]
【The invention's effect】
As it is polished in a state where the ferrule is cooled or the temperature of the ceramic sleeve is raised from other parts,
As described above, based on the difference in linear expansion coefficient between the plastic body and the ceramic sleeve,
The protrusion of the ceramic sleeve from the end face of the ferrule main body can be prevented. Therefore, the following is achieved.
{Circle around (1)} At the time of connector connection, an increase in connection loss due to the end face of the optical fiber being brought into a non-contact state can be prevented.
(2) The temperature dependence of the connection loss is reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory view of Embodiment 1 of the present invention, wherein (a) shows a state in which a ferrule is polished while being cooled in a constant temperature bath, and (b) shows a state in which the ferrule is removed from the constant temperature bath after polishing. .
FIG. 2 is an explanatory view of Embodiment 2 of the present invention.
3A and 3B are explanatory views schematically showing a state before assembling an MT connector, wherein FIG. 3A is a perspective view of one ferrule, FIG. 3B is a plan view, and FIG. 3C is a side view.
FIG. 4 is an explanatory diagram of a connection state of an MT connector.
FIG. 5 is an explanatory diagram of a problem to be solved by the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Optical fiber ribbon 12 Optical fiber 20 Ferrule 22 Ferrule main body 24 Pin guide hole 26 Ceramic sleeve 30 Guide pin 32 Clamp spring 34 Polishing plate 36 Thermostat 38 Pin 40 Heater

Claims (2)

When polishing the end face of a ferrule in which a guide hole lined with a ceramic sleeve is provided in a ferrule body made of plastic, the ferrule is cooled so that the tip of the ceramic sleeve projects somewhat from the end face of the ferrule body. A method for polishing an optical fiber connector, wherein the end face of the ferrule is polished in a state where the ferrule has been set. When polishing the end face of a ferrule in which a guide hole lined with a ceramic sleeve is provided in a ferrule body made of plastic, the temperature of the ceramic sleeve is raised from the other portion when polishing the end face, and the tip of the ceramic sleeve is brought into contact with the ferrule body. Polishing the end face of the ferrule in a state where the end face protrudes slightly from the end face of the optical fiber connector.

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