JPS5857722B2 - fiber optic connector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a splicer used for optical fiber fusion splicing using a CO2 laser, which is one of the fusion splicing methods for optical fibers, by making efficient use of a laser light source. The present invention relates to a small and easy-to-use optical fiber connector that reduces restrictions on the connection work area due to the laser head and power supply that occupy most of the occupied space.

Optical fiber connections are one of the important technologies required to realize optical communication systems.

Conventionally, a connection method using a removable connector, a fixed connection method using an adhesive, a connection method by heat-sealing fibers, and the like are well known.

Among these, the fusion splicing method is an extremely effective connection because it has the following characteristics: ■ low splice loss, ■ small aging of the spliced part, and ■ mechanical strength of the spliced part that is the same as that of bare optical fiber. It's a method.

Heat sources for fusion include nichrome heater, arc discharge, CO
2 laser etc. are used.

When a CO2 laser is used as a heat source, there is no contamination from heat sources such as arc discharge, so a very high quality connection can be achieved, and the unidirectionality of the laser beam can be used to create a connection device that is easy to work with. It can be made.

However, in conventional fusion splicing equipment using a CO2 laser, only a portion of the laser beam is used as a heat source, which necessitates the use of a high-output CO2 laser head and power supply, and the entire equipment is Due to its large size, there is no problem in using it inside a factory or a station, but
The disadvantage was that it was not suitable for use inside tunnels, manholes, or on utility poles.

Figure 1 shows the conventional optimal fusion conditions: laser power 3W, beam diameter 1 peak, and the most common outer diameter 150 μm.
This figure shows how the ends 2 and 2' of the two optical fibers 1 and 1' are heated and fused together.

a shows where the fiber touches the end of beam 3 and the temperature rise begins, b shows the fiber is located in the center of the beam,
The fusion splicing is shown, b' is a side view thereof, and C is the final stage of the fusion splicing.

Here, the propagation direction of the laser beam at a, b, and c is
The direction b/ perpendicular to the plane of the paper is a direction parallel to the plane of the paper.

It is clear that at each step a-e the fiber touches only a portion of the beam and the majority of the beam is not utilized as a heat source.

Figure 2 shows the experimentally determined relationship between the minimum net power required to melt the fiber and the beam diameter.

From this figure, it is clear that when the beam diameter is 1, approximately 0.6 W is enough to melt the fiber, and it can be seen that 2.4 W, which is 80% of the 3 W, is not utilized as a heat source. .

On the other hand, as a method of efficiently utilizing the laser beam, a method can be considered in which the fiber is melted at the most focused point of the laser beam, that is, at the point near the focal point of the focusing lens, where the beam diameter is small and the energy density is high.

However, this method can only melt a minute portion, and the conditions for uniform heating over a wide range necessary for fusion are not met.
It is difficult to achieve low-loss connections with good reproducibility and is not practical.

The present invention was made to eliminate these drawbacks, and instead of focusing the laser beam only with a focusing lens system, it also uses a concave reflecting mirror behind the fiber to be fused. By installing a system and refocusing most of the laser beam, which was not used in the past, onto the fiber position, high-quality connections can be made using a low-output, small-sized CO2 laser light source.

The present invention will be explained in detail below with reference to the drawings.

Fig. 3 shows one example of an optical fiber connector embodying the present invention.
FIG. 2 is a block diagram for explaining how a pair of optical fibers are heated.

The laser beam 5 emitted from the CO2 laser light source 4 is reflected by a reflecting mirror 6.
and is focused by lens 7.

A portion of the focused laser beam 3 irradiates the ends 2 and 2' of the two optical fibers 1°1' to be connected, but since the outer diameter of the fiber is smaller than the beam diameter, 80% A laser beam of about 100% passes through the fiber without irradiating it.

Reference numeral 8 denotes an ellipsoidal concave mirror, which functions to refocus the laser beam 9 that has passed through without irradiating the fiber, and irradiates the fiber.

Here, 10 and 10' indicate the two focal points of the ellipsoidal concave mirror.

10 also coincides with the focal point of the focusing lens 7.

In this way, the end 2.2' of the optical fiber 1,1'
They are connected by being heated and melted by a laser beam from this direction.

FIG. 4 is a side view of one embodiment of the optical fiber connector of the present invention, in which 3 is a focused laser beam, 4 is a CO2 laser light source, 5 is a laser beam, 6 is a reflecting mirror, and 7 is a focusing lens. , 8 is an ellipsoidal concave reflector, 9 is a beam reflected by the concave reflector 8, 11 is a left fiber holding jig, 1
1' is a right fiber holding jig, 12 is a groove jig, 13 is a spring for applying impact pressure, 14 is a disposal groove, and 15 is a base.

In this embodiment, a small waveguide laser is used as the CO2 laser light source 4.

The fibers are held by left and right holding jigs 11 and 11', aligned parallel to each other by a grooved jig 12, and subjected to impact pressure by a spring 13 and a micrometer (not shown). It will be confronted with.

A stop groove 14 is formed where the left and right end surfaces abut against each other, and the bottom surface of the stop groove 14 serves as a concave reflecting mirror 8.

At the center of this groove 14, the fiber receives the laser beam 3 focused by the focusing lens 7 from above, receives the laser beam 9 focused again by the concave reflector 8 from below, and receives it from both the upper and lower directions. They are uniformly heated and melted and fusion spliced.

Further, in the embodiment of the optical fiber connector of the present invention, the concave reflecting mirror 8 is incorporated in the V-groove jig 12, and a wide free space is provided between the lens 7 and the V-groove jig 12. .

Therefore, the work of attaching and removing the fiber to and from the V-groove jig 12 and the work of fusion splicing are easy to perform, and no deterioration in work efficiency due to irradiation with the laser beam from two directions is observed.

In this embodiment, a spherical lens is used as the focusing lens, but the effect is the same even if a cylindrical lens is used.

Furthermore, since a slight decrease in beam focusing efficiency at the fiber position is acceptable as a reflective concave mirror, it does not necessarily have to be a strict ellipsoid, and a spherical reflective mirror can be used instead.

As explained above, the optical fiber connector of the present invention uses a concave mirror to refocus the laser beam that was conventionally scattered and efficiently irradiates the fiber, so it
An O2 laser light source can be used, and the laser head and power supply, which take up most of the weight and space of the connector, can be replaced with something much smaller, such as a waveguide CO2 laser.

Therefore, the entire connector can be made significantly smaller, lighter, and more economical.

Furthermore, since the fiber is heated and melted by uniformly irradiating the fiber from two directions while keeping the beam diameter large, there is an advantage that high-quality connections can be made with good reproducibility.

The laser beam is irradiated from two directions in this splicer, and this uses a reflective mirror in the fusion splicer.
There are no obstacles between the focusing lens and the groove jig, and there is a wide free space, which has the advantage of good workability for attaching and detaching the fiber, and ease of use.

Therefore, the optical fiber connector of the present invention is extremely effective when used for connecting optical fibers for optical communication, which requires quick connection, low loss, and good reproducibility, and in some cases, in a narrow working space. It is.

[Brief explanation of the drawings] Figure 1 is a diagram to explain how a fiber is heated by a conventional connector using a CO2 laser as a heat source, and Figure 2 is a diagram showing the minimum net power required to melt the fiber. A graph showing the relationship between beam diameters, FIG. 3 is a block diagram for explaining the state of heating of a pair of optical fibers in the connector of the present invention, and FIG. 4 is a side view of one embodiment of the connector of the present invention. It is a diagram. 1...Left side optical fiber, 1'...Right side optical fiber 2...Left side optical fiber end, 2'...
... right side optical fiber end, 3 ... focused laser beam, 4 ... CO2 laser light source,
5...Laser beam, 6...Reflector,
7...Focusing lens, 8...Ellipsoidal concave reflecting mirror, 9...Laser beam reflected by the ellipsoidal concave reflecting mirror, 10...Focusing The focal point of the lens 7 and one focal point of the ellipsoidal concave reflector 8, 10/.
.....Another focal point of the ellipsoidal concave reflector, 11.
...Left fiber holding jig, 11'...
Right side fiber holding jig, 12...■Groove jig, 1
3... Spring for applying impact pressure, 14... Seating groove, 15... Base.

Claims (1)

[Claims] 1. A CO2 laser light source, a focusing lens to focus the laser beam on the connection end, and two devices to reflect the diverging laser beam after irradiating the fiber and refocus it on the connection end. An ellipsoidal concave reflector having a focal point, a fiber alignment jig for keeping the axes of two optical fibers aligned, and movement for moving the fiber or laser beam at a constant speed in a direction perpendicular to the fiber axis. It is equipped with an ellipsoidal concave reflector that is integrated into a fiber alignment jig, and a rammed coining button mechanism that butts the connecting ends of optical fibers against each other with a constant pressure. Optical fiber connector.