JPH06109987A - Optical switch - Google Patents

Abstract

PURPOSE:To obtain an optical switch which shows little change in characteristics (insertion loss or reflected light) in accordance with temp. change. CONSTITUTION:The movable optical fiber type light switch consists of a movable optical fiber 21 and a fixed optical fiber 22a. Two fibers are connected by forming the end surfaces of two fibers oblique to the optical axis and parallel to each other, and filling the space between two fibers with a liquid 11 (matching agent for refractive index) having almost same refractive index as that of the core of the optical fiber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable optical fiber type mechanical optical switch used for optical communication and the like.

[0002]

2. Description of the Related Art A mechanical optical switch having a structure in which an optical fiber is directly driven to switch an optical path has a characteristic that the structure is simple and low insertion loss, downsizing, and low driving power can be obtained. Many types of switch structures have been proposed so far.

FIG. 2 shows an embodiment of a conventional optical fiber direct drive type optical switch. FIG. 2A is a perspective view showing the structure. This mechanical optical switch is of the 1 × 2 type and has a base fixed to a cylindrical tube 29 in a cantilever shape, and a magnetic film 23 having desired magnetic characteristics near the tip thereof.
Fixed movable optical fiber 21 and solenoid coil 2 provided to reverse the magnetic poles at both ends of the magnetic film 23.
4, permanent magnets 25a and 25b for applying a magnetic attraction force to the magnetic film 23 in a direction perpendicular to the optical axis, and a half cylinder 28.
a, 28b, a cylindrical tube 29, and half-cylinders 28a, 28b in alignment, and a cylindrical sleeve 27 for fixing the solenoid coil 24 and the permanent magnets 25a, 25b.

FIG. 2 (b) shows a radial cross-sectional shape of the half-split cylinders 28a, 28b of the optical switch shown in FIG. 2 (a). V-shaped grooves 26a and 26b are formed in the flat portion where the half cylinders 28a and 28b are joined. V-shaped grooves 26a, 2
Two optical fibers 22a and 22b are fixed to 6b as shown in the figure.

The permanent magnets 25a and 25b are magnetized in opposite axial directions. The operation of this switch is as follows. The movable optical fiber 21 is magnetically attracted to either one of the pair of permanent magnets 25a and 25b according to the magnetic poles at both ends of the magnetic film 23, and the two fixed optical fibers 22a and 22a on the V-shaped grooves 26a and 26b. Optically coupled to either one of 22b. When the magnetic poles on both ends of the magnetic film 23 are reversed by energizing the solenoid coil 24 and applying a magnetic field along the optical axis to the magnetic film 23, the movable optical fiber 21 is attracted to the other permanent magnet side and the other side of the magnetic film 23 is attracted. Optically couples to a fixed optical fiber. Even when the current is not supplied,
Since the magnetic body 23 is magnetically attracted to one of the permanent magnets 25a and 25b, one of the fixed optical fibers 22
It is possible to maintain the binding state with either a or 22b,
A self-holding switching operation can be obtained.

FIG. 2C is a side view of the facing portion when the movable optical fiber 21 and the fixed optical fiber 22a face each other. As shown in the figure, each fiber is polished so that its end face is substantially perpendicular to the optical axis, and is arranged in a space with a predetermined interval. Hereinafter, a fiber polished so that its end face is substantially perpendicular to the optical axis is called a flat end optical fiber.

[0007]

However, in the above optical switch, when the optical fiber expands or contracts due to temperature fluctuations or the like, there is a drawback that the insertion loss greatly changes as the optical fiber gap increases or decreases.

In a high-speed optical communication system, the reflected return light largely affects the light source, and the reflected return light is desired to be as small as possible. The optical switch has a drawback that the light in the optical fiber is reflected due to the reflection by the air layer in the gap between the optical fibers, and the reflected return light (reflection attenuation amount) becomes large.

Therefore, the present invention solves the above-mentioned drawbacks and the characteristics (insertion loss and reflected return light) associated with temperature fluctuations.
An optical switch with less fluctuation is provided.

[0010]

In order to achieve the above object, an optical switch according to the present invention has a movable optical fiber whose end face is displaced in the radial direction, and a front end of the movable optical fiber and a front end of itself. In an optical fiber that is composed of a plurality of fixed optical fibers that are fixed, and an end face of the movable optical fiber that switches the optical path by being held facing one of the plurality of fixed optical fibers according to its displacement. , The movable optical fiber and the fixed optical fiber of the optical fiber movable type optical switch are formed so that both end faces facing each other are oblique to the optical axis and the end faces are parallel to each other, and the refractive index of the core portion of the optical fiber is A liquid having a refractive index close to that (hereinafter referred to as a refractive index matching agent) is filled in the gap between the optical fibers.

[0011]

In the optical switch according to the present invention, since the refractive index matching agent is filled in the gap between the movable and fixed optical fibers, the reflected return light at the end face of the optical fiber can be suppressed and the insertion loss due to Fresnel reflection or the like. It is possible to suppress a sharp change in the insertion loss caused by an increase in the optical fiber gap and an increase or decrease in the optical fiber gap. Further, since the end faces of the optical fiber are formed obliquely and parallel to each other, the reflected return light can be further suppressed, and the reflected return light due to the change in the refractive index of the refractive index matching agent due to the temperature change can be further suppressed. Can be suppressed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 (a) and 1 (b) are a perspective view and an axial cross section for explaining a state of a movable optical fiber and a fixed optical fiber end face of a 1 × 2 optical switch which is one of embodiments of the present invention. It is a figure. In the figure, the same components and parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted.
Further, in this embodiment, the end faces of the movable optical fiber 21 and the movable optical fibers 22a and 22b facing each other are formed obliquely so as to be parallel to each other, and a gap is filled with a refractive index matching agent. Unlike the conventional optical switch of FIG. 2, the other configurations are the same. Therefore, the description of the operation of the present optical switch is omitted.

In the present embodiment, the refractive index matching agent is filled only in the gap between the optical fibers, but it is also possible to fill the entire internal cavity of the optical switch with the refractive matching agent and seal it. As a method for forming the slant of the end face of the optical fiber, there are methods such as a polishing method and a cleaving method. In this embodiment, a jig of a commercially available optical fiber cleaver is improved so that the optical axis of the optical fiber is 8 °. I made an angle. Although the angle of the end face of the optical fiber is 8 ° in this embodiment, it may be any number as long as a sufficient effect can be obtained. However, if the surplus angle becomes large, the insertion loss due to the gap becomes large, so it is necessary to consider it.

Curves A and B in FIG. 3 are curves showing the relationship between the optical fiber gap and the insertion loss of the conventional and the optical switches according to the present invention. As is clear from this curve, it can be seen that the optical switch according to the present invention has a gentler tendency to increase the insertion loss as the optical fiber gap increases, as compared with the conventional optical switch.

Table 1 is a table comparing the representative values of the reflected return light of the optical switch of the present invention and the conventional optical switch, and it can be seen that the optical switch of the present invention has low reflection.

[0016]

[Table 1]

Table 2 shows fluctuations of reflected return light during the temperature test of the optical switch of the present invention and the optical switch in which the flat-end optical fiber is filled with the index matching agent.

[0018]

[Table 2]

When a flat end optical fiber is used,
The refractive index of the refractive index matching agent changes due to temperature changes, and the reflected return light increases. In the optical switch of the present invention, since the end face of the optical fiber is formed obliquely, it is possible to prevent a sharp increase in reflected return light. In the optical switch of the present invention, in order to reduce the insertion loss as much as possible, the end faces of the obliquely formed optical fibers are made parallel to each other.

[0020]

As described above, in the optical switch according to the present invention, the end faces of the optical fiber are formed obliquely and parallel to each other, and the core of the optical fiber having the refractive index is provided in the gap between the movable and fixed optical fibers. Since it is filled with a liquid that has a refractive index close to that of the optical fiber, it is possible to suppress the reflected return light at the end face of the optical fiber, and to increase the insertion loss due to Fresnel reflection and increase or decrease the optical fiber gap. Can be suppressed. Furthermore, it is possible to suppress a sharp increase in reflected return light due to a change in the refractive index of the refractive index matching agent due to a change in temperature.

[Brief description of drawings]

FIG. 1A is a perspective view of an optical fiber end face facing portion of an optical switch of the present invention, and FIG. 1B is an axial sectional view of an optical fiber end face facing portion of the optical switch of the present invention.

2A is a structural explanatory perspective view of a conventional optical switch, and FIG. 2B is a structural explanatory sectional view of a conventional optical switch.

FIG. 3 is a diagram showing a relationship between an optical fiber gap and insertion loss.

[Explanation of symbols]

 11 Refractive Index Matching Agent 21 Movable Optical Fibers 22a, 22b Fixed Optical Fiber 23 Magnetic Film 24 Solenoid Coils 25a, 25b Permanent Magnets 26a, 26b V-Shaped Groove 27 Cylindrical Sleeves 28a, 28b Half Cylinder 29 Cylindrical Tube

Claims (1)

[Claims] 1. A movable optical fiber whose end face is displaced in the radial direction, and a plurality of fixed optical fibers fixed so that the front end of the movable optical fiber and its own end face each other, and the end face of the movable optical fiber is , In an optical switch that switches the optical path by being held facing any one of the plurality of fixed optical fibers according to the displacement, both end surfaces of the movable optical fiber and the fixed optical fiber with respect to the optical axis. A light which is obliquely formed and is parallel, and a liquid having a refractive index close to that of the core of the optical fiber is filled in a gap between the movable optical fiber and the fixed optical fiber. switch.