JPH073511B2 - Optical switch manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing an optical switch.

[Conventional technology]

Various fiber-switch type optical switches have been proposed so far, but among them, those shown in FIGS. 3 and 4 are known as those having a relatively small size and a simple structure. That is, Fig. 3 shows an optical switch devised by PGHale et al. (Electoronics Letter, Vol.12. No. 1
5), a glass tube 1 having a square cross section, a movable fiber 2 having a nickel sleeve 3 at its free end, and a movable fiber 2
Two fixed fibers arranged corresponding to the free ends of the 4
It is composed of A, 4B and coils 5A, 5B as a magnetic field generating mechanism arranged corresponding to the nickel sleeve 3, and drives the movable fiber 2 by an external magnetic field generated by these coils 5A, 5B. Thus, the switching operation is performed by selectively facing either one of the fixed fibers 4A and 4B. This type of optical switch always uses coils 5A and 5A to maintain the connection between the opposing fibers.
This is a current-holding type optical switch that requires an external magnetic field to be generated by passing a current through B, and its magnetic field generation mechanism is also relatively large.

On the other hand, FIG. 4 shows a magnetic film coated fiber movable type optical switch having a self-holding function, which was devised by the present inventors for the purpose of a small-sized and low-power driven optical switch (Japanese Patent Application No. 58-2704).
No. 8 (JP-A-59-154406). That is, this switch has a cantilevered movable fiber 2 formed by forming a magnetic film 10 near the tip of the fiber by an electrodeposition method or the like, and a diamond-shaped fiber insertion hole 12 formed at one end of the housing 11 at one end. 2 fixed fibers 4A and 4B fixed in the corners of the hole 12 that are opposed to each other vertically and the magnetization directions (arrows A and B directions) of the magnetic film 10 along the fiber optical axis are reversed. It is composed of a solenoid coil 13 as a means for causing the magnetic film 10 and a pair of permanent magnets 15A, 15B which are arranged to face each other across the magnetic film 10 and apply a magnetic attraction force to the magnetic film 10 in a direction perpendicular to the fiber optical axis. , The movable fiber 2 is magnetically attracted to either one of the upper and lower permanent magnets 15A and 15B according to the magnetic poles at both ends of the magnetic film 10, and the tip end surface thereof is fixed in the fiber insertion hole 12. Switch either by selectively facing either 4A or 4B It is those that were, solenoid coil
A self-holding type switching operation can be obtained only by supplying positive and negative current pulses to 13.

The movable fiber type optical switch seen in these prior arts is considered to be highly practical due to its simple structure. However, in manufacturing it, the optical fiber between the movable and fixed fibers facing each other is decreased in order to reduce the insertion loss of the switch. It is essential to align the axes with high accuracy. When these optical switches are viewed from the viewpoint of alignment of the optical axes, the fibers are coupled inside the fiber insertion hole, so there is no vertical shift from the optical axis, and the factors causing the axial shift are the movable fiber and the fixed fiber. It is limited to the angle gap between the fiber gap between the movable fiber and the fixed fiber and the end face of the movable fiber facing the fixed fiber. Among these, the increase in loss due to the angular displacement can be sufficiently avoided in the optical switch having the structure shown in FIG. 4 depending on the design conditions.

That is, in FIG. 5 (A), the magnetic attraction force to the movable fiber 2 is F, (However, if E is the longitudinal elastic modulus of the fiber and I is the second moment of area of the fiber), if F is set between Fmin and Fmax, the tip of the movable fiber 2 will be parallel to the fiber insertion hole 12. It becomes possible to maintain the optical axis angle deviation between the opposing fibers 2 and 4B at this time (θ = 0). If the magnetic attraction force F is out of this range, an angle shift occurs as shown in the figure (θ ≠ 0). FIG. 6B is an experimental verification by observing the optical output that the angle shift occurs as the magnetic attraction force F increases, and the loss increases. The angle shift in the regions B to C is shown. You can see that is 0. Therefore, the deviation of the optical axis angle between the fibers 2 and 4B can be avoided by the optimum design of the magnetic attraction force F, the size of the movable fiber 2 and the arrangement condition, and the fiber 2 can be used to reduce the insertion loss. It is important to reduce the fiber gap (Z) from 4B.
Fig. 6 is a diagram showing the relationship between the fiber gap Z and the insertion loss. In the case of the optical switch shown in Fig. 4 in which fibers 2 and 4B (flat end fibers) whose opposite end faces are flat are coupled to each other, the curve is shown. A, the insertion loss tends to increase monotonically as the fiber gap Z increases. As is clear from the figure, in order to reduce the insertion loss to 0.5 dB or less, it is necessary to set Z to 5 μm or less, which requires extremely accurate fiber alignment work when manufacturing the optical switch. Even if the fiber gap Z can be set as described above, when the fibers 2 and 4B expand and contract due to temperature fluctuations and the like, the movable fiber 2 hits the fixed fiber 4B and the switch operation becomes impossible. Since the tendency of the increase of the loss with respect to Z and the steepness of Z is steep, a large increase of the loss due to the temperature change is expected and the stability is lacking.

[Problems to be solved by the invention]

As described above, conventionally, when manufacturing a movable fiber type optical switch, it was necessary to adjust the gap (Z) between the movable and fixed fibers with high precision, and the assembling work was complicated. Furthermore, even with an optical switch whose fiber gap is adjusted with high accuracy, when the fiber expands and contracts due to temperature fluctuations, etc., the switch operation becomes impossible, and the increase in insertion loss is remarkable as the fiber gap increases. There were some shortcomings.

Therefore, the present invention solves the above-mentioned drawbacks,
It is an object of the present invention to provide a method for manufacturing an optical switch in which the fiber gap can be increased without increasing the insertion loss, the assembling workability is improved, and the characteristic variation due to the temperature variation is small.

[Means for solving problems]

In order to achieve the above object, the optical fiber manufacturing method according to the present invention has one end portion of a plurality of fixing fibers inserted and fixed in the insertion hole of a housing having a polygonal fiber insertion hole, and a magnetic film near the tip. A movable fiber provided with a penetrating through the center of the housing, the free end of which is inserted into the fiber insertion hole and overlapped with the fixed fiber;
The overlapping parts of these two fibers are cut and separated at an arbitrary position, and the cutting liquid is injected into a groove formed in the housing by this cutting and is etched for a certain period of time to make the cut end faces of both fibers into a convex spherical shape. Then, the etching liquid and unnecessary portions of the fixed fiber are removed, and then means for applying a magnetic field for driving the movable fiber is arranged corresponding to the magnetic film. .

[Work]

In the method for manufacturing an optical fiber according to the present invention, the fixed and movable fibers are cut at arbitrary positions where they overlap each other, so that the fiber gap need not be adjusted.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of an optical switch manufactured by the method for manufacturing an optical switch according to the present invention. The same components and parts as those in FIG. 4 are designated by the same reference numerals and the description thereof will be omitted. In the figure,
In this embodiment, the end faces 20, 21, 22 of the movable fiber 2 and the fixed fibers 4A, 4B facing each other are formed in a convex spherical shape, and the housing 11 is covered with the cover 23, and the fiber insertion hole 12 of the housing 11 is formed. Different from the conventional optical switch shown in FIG. 4 in that a groove 24 for setting a fiber gap is formed at one end of the optical switch, the other structure is the same. The end faces 20, 21, 22 are formed in a convex spherical shape. There are various methods such as a polishing method, a heat melting method and an etching method. In this embodiment, a buffered hydrofluoric acid solution [48% HF (1): 40% NH _{4 is used].}
F (10)] with fiber end faces 20, 21, 22 (core diameter 50 μm, outer diameter 1
25 μm, GI type) was used for the chemical etching method in which the fiber core part was processed into a convex spherical surface. The etching conditions are a liquid temperature of 60 ° C. and an etching time of 8 minutes.

A curve B in FIG. 6 is a curve showing the relationship between the fiber gap and the insertion loss of the optical switch according to the present invention, and as is apparent from this curve, the fibers whose opposing end faces 20, 21, 22 are processed into a convex spherical surface. It will be understood that in the coupling of (1), the tendency of the insertion loss increase with the increase of the fiber gap is remarkably alleviated as compared with that of the flat end fiber described above. For example, to maintain the insertion loss of 0.5 dB,
In case of flat end fiber, the fiber gap should be 5μ.
It is necessary to keep it below m, but in the case of a convex spherical surface processing fiber, a fiber gap of about 80 μm is allowed. The fluctuation of the insertion loss in the range of the fiber gap of 50 μm to 100 μm is about 0.15 dB at most. These characteristics are considered to be obtained because the optical coupling system that is close to the collimated beam is constructed between both fibers by the convex spherical surface processing fiber, and the workability of the fiber alignment, which is the most important step during switch assembly. It is possible to ensure stable characteristics even when the fiber gap is increased or decreased due to temperature changes and the like.

Although the relationship between the fiber gap between the convex spherical surface processing fibers formed by the polishing method and the heat melting method and the insertion loss is similar to that in FIG. 6B, the reproducibility of the processing is poor and the tendency of the loss increase tends to occur. Steeper than that by. In addition, in the case of convex spherical surface processing fiber formed by polishing method and heat melting method, the fiber alignment work by manipulator etc. is required at the time of assembling the switch. Is possible and the merits of this processing method are great.

Next, a method of manufacturing the optical switch according to the present invention will be described with reference to FIG. First, as shown in FIGS. 3A and 3B, a movable fiber insertion hole 30 is provided at one end and a fiber insertion hole 12 for optical axis alignment between the movable and fixed fibers is provided at the other end.
A housing 11 having a is prepared. Next, the fixed fiber
Insert one end of 4A, 4B into the fiber insertion hole 12
Adhere and fix to the corners of 2 facing each other. At this time, the movable fiber 2 provided with the magnetic film 10 is also inserted into the fiber insertion hole 12 and the small hole 30 so that both ends are formed in these holes 1.
The protrusions 2 and 30 are protruded to the outside, and the holes 12 and 30 are fixed by adhesion. Therefore, the movable fiber 2 and the fixed fiber 4A, 4B
Part of each overlaps inside and outside the fiber insertion hole 12. Next, as shown in FIG. 2C, the overlapping portion of the movable fiber 2 and the fixed fibers 4A and 4B together with the housing 11 at a predetermined position of the fiber insertion hole 12 has a predetermined thickness in the direction perpendicular to the optical axis. The blade 40 cuts. The groove 24 shown in FIG. 1 is formed by this blade 40. The groove 24 is filled with the buffer hydrofluoric acid solution 41 as shown in FIG. 3D, and the cut end faces of the movable fiber 2 and the fixed fibers 4A, 4B are etched at a predetermined temperature for a certain period of time to form a convex spherical surface. Form the end face. Thereafter, the unnecessary fixed fiber pieces 42a, 42b are cut out from the fiber insertion hole 12 and the cut end of the movable fiber 2 is movable in the fiber insertion hole 12 in the radial direction to complete the switch body. FIG. 1 is completed by mounting the above-mentioned cover 23 on the switch body manufactured in this way to prevent dust from entering the gap between the fibers, and providing the solenoid coil 13 and the pair of permanent magnets 15A and 15B. It is a light switch.

In the above embodiment, the switch for the magnetic film coated fiber movable type 1 × 2 light having a self-holding function has been described, but the invention is not limited to this, and the number of fixed fibers may be increased if necessary. Needless to say, the fiber insertion hole 12 may be formed in a triangular shape, a pentagonal shape, or the like, and the means for driving the movable fiber 2 may be increased accordingly.

〔The invention's effect〕

According to the optical switch manufacturing method of the present invention, it is possible to perform lens processing by fiber cutting and etching in the optical switch assembling process, and it is possible to simplify the process without requiring fiber alignment and to improve workability. It can be significantly improved.

[Brief description of drawings]

FIG. 1 is a sectional view of an optical switch manufactured by the method for manufacturing an optical switch according to the present invention, and FIGS. 2A to 2D are views showing the manufacturing method according to the present invention, FIGS. 3 and 4. Is a cross-sectional view and a partially cutaway perspective view showing a conventional example of a movable fiber type optical switch, and FIGS.
Fig. 6 shows the measurement result of the optical axis angle deviation between fixed fibers and the loss fluctuation due to this deviation. Fig. 6 shows the fiber gap and insertion loss between flat end fibers and between convex spherical fibers. It is a figure which shows a relationship. 2 ... Movable fiber, 4A, 4B ... Fixed fiber, 10 ...
Magnetic film, 11 …… Housing, 12 …… Fiber insertion hole, 13
...... Solenoid coil, 15A, 15B ...... Permanent magnet, 20,21,2
2 ... Opposing end face, 41 ... Etching liquid.

Claims (1)

[Claims] 1. An end portion of a plurality of fixed fibers is inserted and fixed in the fiber insertion hole of a housing having a fiber insertion hole, and a movable fiber having a magnetic film near the free end is penetrated through the center portion of the housing. , Its free end is inserted into the fiber insertion hole and overlapped with the fixed fiber, and the overlapping portions of both fibers are cut and separated at an arbitrary position, and an etching solution is applied to a groove formed in the housing by this cutting. By injecting and etching for a certain period of time, the cut end faces of the both fibers are formed into a convex spherical surface, then the etching liquid and unnecessary portions of the fixed fiber are removed, and then a magnetic field for driving the movable fiber is applied. A method for manufacturing an optical switch, characterized in that the applying means is arranged corresponding to the magnetic film.