JP2003090968A - Optical switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-size optical switch with low loss by which high reproducibility is attained. SOLUTION: The optical path of a light beam from an incident optical fiber is branched by a reflective mirror of the optical switch so as to switch the optical path from one of two output optical fibers to the other, or the relation of the input and output fibers are reversed in the optical switch. In the optical switch, the distance between the incident optical fiber to the reflective mirror is different from the distance between the output optical fiber and the reflective mirror.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch which is inserted into an optical fiber transmission line for optical communication or the like to switch the transmission line.

[0002]

2. Description of the Related Art Conventionally, many types of optical switches have been proposed. Among them, as a mechanical switch, a magnetic film 5 added to an optical fiber 1A as shown in FIG. 13 disclosed in Japanese Patent Laid-Open No. 63-313111 is directly driven by a magnetic coil 4 to provide an optical path from 1A to 1B. An optical fiber movable type 1 × 2 switch having a structure for switching 3 to 1C has been proposed. Optical fiber 1
A, 1B, and 1C are fixed to holders 6A and 6B, and the magnetic film 5 of the optical fiber 1A is self-held by the magnetic force of the permanent magnet 7 provided on the outer peripheral portion of the magnetic coil 4.

Further, the optical path is switched by driving a micro optical element such as a mirror or a prism. JP-A-54-162551
14 and 15 disclosed in Japanese Patent Application Laid-Open No. 55-87107 and Japanese Patent Laid-Open No. 55-87107, a micro optical element movable type 1 × 2 optical switch is also disclosed. In the optical switch shown in FIG. 14, the optical fibers 1A, 1B, and 1C are arranged at 120 ° intervals on the circumference centered on the reflection surface of the reflection mirror 2. The optical path 3 from the optical fiber 1A is emitted as a parallel beam by an optical system including a lens added to the optical fiber, reflected by the reflection mirror 2, and is incident and coupled to the optical fiber 1B for output. Each optical fiber is selected by controlling the rotation angle of the reflection mirror 2.

In FIG. 15, the optical fibers 1B, 1C, 1D, 1E, 1F, 1G are arranged on the circumference centered on the optical fiber 1A.
, The optical path 3 from the optical fiber 1A is emitted as a parallel beam by the optical system of the lens added to the optical fiber, is reflected by the two 45 ° reflection mirrors 2, and is returned to the optical fiber 1B. Incident coupling is output. Each optical fiber is selected by controlling the rotation angle of the reflection mirror 2. The prism and mirror in the conventional micro optical element movable type switch controlled the mechanical rotation angle and position by a pulse motor etc.
In optical fiber coupling used for optical communication, submicron-order alignment is required. Therefore, in position control using a pulse motor, etc., the rotational angle accuracy is about 0.5 °, so reproducibility is poor and loss is lost. It was causing an increase. In addition, it is necessary to constantly apply an electric field to the motor, which constantly requires electric power.

[0005]

When the rotation angle of the reflecting means such as the mirror in the conventional micro optical element movable type switch as shown in FIG. 14 is large, the optical switches are arranged radially. However, there is a problem that the installation area becomes large. In addition, FIG. 2 illustrates the configuration of another conventional optical switch. When the separation angle θ due to the rotation of the reflecting means as shown in FIG. 2 is small, the relationship between the reflecting means, the incident optical fiber, and the outgoing optical fiber is arranged at the same position, so that they do not interfere with each other. Therefore, it is necessary to increase the distance between the optical fiber and the reflecting means, and the entire optical switch is large. An outline of the configuration of FIG. 2 will be described with reference to FIG. First, in the conventional optical switch, the light beam is distributed from A to B or C at the rotation angle θ of the reflection mirror 2. The light beam from A to B enters and exits at an angle of φ1 with respect to the normal direction d1 of the reflecting mirror 2 and from A to C at an angle of φ2. Here, φ1 and φ2 are half the rotation angle θ of the reflecting mirror, and φ1 = φ2 = θ / 2. A lens for converting the light beam into a parallel beam is added to the actual incident optical fiber, and the light separated by the reflection mirror 2 must enter the center of the lens of the output fiber. Need to be separated between each optical fiber. When this distance is d, the distances Lb and Lc from the reflection mirror 2 to the output optical fiber are Lb = Lc = d / tan (φ1).

FIG. 6 shows the calculation results when the rotation angle θ of the reflecting mirror 2 with respect to the distance d is 4, 6, 8 and 10 °. If the rotation angle θ is small, the distance L between the reflection mirror 2 and the optical fiber
Needs to be long. The diameter of the lens used is about 3.2 mm
Considering this, the distance d needs to be 2 mm or more in consideration of the light beam diameter. If the rotation angle θ is 8 °, the distance between the reflection mirror 2 and the optical fiber becomes about 28 mm, and the optical switch becomes large. In this case, since the optical path length from the incident optical fiber to the output optical fiber is as large as 56 mm, there are problems such as an increase in coupling loss to the optical fiber, and it is difficult to reduce the loss. An object of the present invention is to solve such problems in the related art and to manufacture a small-sized and low-loss optical switch capable of highly accurate positioning and reproducibility.

[0007]

The optical switch of the present invention comprises:
An optical switch for branching an optical path of a light beam from an incident optical fiber by a reflection mirror to switch the optical path from one of the two output optical fibers to the other,
The distance between the incident optical fiber and the reflection mirror and the distance between the output optical fiber and the reflection mirror are different from each other. Further, in the above-mentioned present invention, it is desirable that the incident beam angle from the incident optical fiber to the reflection mirror is 10 ° or less. The rotation angle of the reflection mirror is 10
The angle between the two output optical fibers and the reflection mirror is twice the rotation angle. It is also possible to adopt a configuration in which the light beams from N incident optical fibers are incident on the reflection mirror and N sets of two output optical fibers are provided.

In the optical switch of the present invention, the incident optical fiber can be used as the output optical fiber, and conversely, the output optical fiber can be used as the incident optical fiber.
That is, this corresponds to using the input and output in reverse.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) FIG. 1 is a diagram showing an embodiment of an optical switch applied to the present invention. This optical switch reflects the light beam from the incident optical fiber 1A by the reflection mirror 2 and couples it to the optical fiber 1B. When the reflection mirror 2 rotates by θ, the light beam is coupled to the optical fiber 1C. Incident optical fiber 1A and reflection mirror 2 at this time
Are different in the distances between the output optical fibers 1B and 1C and the reflection mirror 2. The configuration of FIG. 1 will be described with reference to the schematic diagram of FIG. First, since the conventional optical switch of FIG. 2 has a configuration in which the light beam is distributed from A to B or C at the rotation angle θ of the reflection mirror 2, the rotation angle θ = 8 °.
When .theta. Is decreased, the distance (Lb or Lc) between the reflection mirror 2 and the optical fiber becomes about 28 mm, and the optical switch becomes large. In the present invention, the incident optical fiber A is installed on one side, and is incident on the reflection mirror 2 at an incident angle of φ1,
The light is reflected by φ1 with respect to the normal direction d1 of the reflection mirror 2 and output to the output optical fiber B. When the reflection mirror 2 rotates by θ, it is incident on the reflection mirror 2 at an incident angle of φ2, is reflected at φ2 with respect to the normal direction d2 of the reflection mirror 2, and is output to the output optical fiber C. In this case, the distances Lb and Lc between the output optical fibers B and C with respect to the reflection mirror 2 are Lb = Lc =
d / tan (φ3), φ2 = θ + φ1, φ3 = θ, and the angle of the output optical fibers B and C with respect to the reflection mirror 2 is twice the rotation angle θ of the mirror 2. The distance La between the incident optical fiber A and the reflection mirror 2 is La = d / tan (2 · φ1).

In the graph of FIG. 5, the rotation angle θ of the reflecting mirror 2 is 8 ° and the incident angle φ1 of the incident optical fiber is 8 °,
The result of having calculated the distance L between the reflection mirror and the optical fiber with respect to the distance d is shown. For comparison, the calculation result in the case of the conventional optical switch is shown as (La, b, c). Distance d to 2
mm, in the configuration of the present invention, La is about 7 mm, Lb, Lc
Is about 14 mm, which is half the distance of conventional optical switches.

The structure of the optical switch according to this embodiment is shown in FIG. The reflection mirror 2 is installed in the drive unit 8, and the driving method is to cause opposite currents to flow through the electromagnetic coils 9A and 9B to attract or repel the mirror (or the supporting substrate of the mirror) to the electromagnetic coil. To rotate the drive. The case 10 has a width of 19 mm, a length of 27 mm, and a thickness of 8.5 mm.

FIG. 8 shows the results of measuring the change in insertion loss when the optical fiber and lens portion of the optical switch of the present invention are fixed with an adhesive. The horizontal axis is time (Time (min)),
The vertical axis represents insertion loss (Insertion Loss (dB)). Even if the adhesive is completely solidified after the curing time of 30 minutes, there is almost no displacement of the optical fiber or the like, and an insertion loss of 0.32 dB is achieved.

FIG. 9 is a result of measuring the switching characteristics of the optical switch of the present invention, and it can be seen that an optical output is obtained in a switching time of about 3 ms for a switching input pulse of 5 V and 5 ms. FIG. 10 shows the result of measuring the switching time of the optical switch with respect to the pulse width at the input pulse voltage of 5V,
A switching time of about 3 ms is obtained at 0.7 ms or more.
The horizontal axis represents the pulse width, and the vertical axis represents the switching time (ms). FIG. 11 shows the result of measuring the switching time of the optical switch with respect to the pulse voltage in the input pulse width of 5 ms. The minimum driving voltage is 2.5 V or more, and the switching time of 3 ms is obtained at 4 V or more.
The vertical axis represents switching time (Switching time (ms)), and the horizontal axis represents pulse voltage (Voltage (V)).

The optical switch of the present invention has a low insertion loss of 1 dB or less and a high switching time of 3 ms. Further, it was realized as an optical switch having a high reproducibility with an insertion loss of 0.1 dB or less as a reproducibility of 100,000 times. The rotation angle and the incident angle of the incident optical fiber are set to 8 ° in this embodiment, but if the angle is 10 ° or more, the switching time becomes long and the polarization dependency of the insertion loss becomes large, so that it is 10 ° or less. Is needed.

Although the electromagnetic mirror is used to rotate the reflecting mirror 2 in this embodiment, a rotating force may be applied by a stepping motor or the like.

(Embodiment 2) FIG. 12 is a perspective view of another embodiment of the optical switch applied to the present invention. This optical switch has the same optical fiber and reflection mirror structure as in FIG. 1, but a 1 × 2 optical switch, which is a combination of an incident optical fiber and two output optical fibers, is vertically arranged to form a single reflection mirror 2. Is used. In this embodiment, 1 ×
Two switches are switched at the same time, but 1x
By arranging N 2 optical switches, N times 1 × 2 optical switches can be realized. Further, instead of switching to the same direction at the same time, it is possible to control each 1 × 2 optical switch separately and realize switching of different combinations.

[0017]

By changing the arrangement of the input and output optical fibers as a 1 × 2 optical switch, a small optical switch with low loss and high reproducibility can be realized.

[Brief description of drawings]

FIG. 1 is a plan view illustrating a 1 × 2 optical switch according to an embodiment of the present invention.

FIG. 2 is a plan view illustrating a conventional 1 × 2 optical switch.

FIG. 3 is a schematic diagram for explaining the configuration of the present invention.

FIG. 4 is a schematic diagram illustrating a conventional configuration.

FIG. 5 is a graph showing a dL relationship in the present invention.

FIG. 6 is a graph illustrating dL in a conventional optical switch.

FIG. 7 is a plan view illustrating a 1 × 2 optical switch according to an exemplary embodiment of the present invention.

FIG. 8 is a graph illustrating insertion loss according to an example of the present invention.

FIG. 9 is a graph illustrating switching characteristics according to an example of the present invention.

FIG. 10 is a graph illustrating a switching time according to an exemplary embodiment of the present invention.

FIG. 11 is a graph illustrating a drive voltage and a switching time according to an embodiment of the present invention.

FIG. 12 is a perspective view illustrating a 1 × 2 optical switch according to another embodiment of the present invention.

FIG. 13 is a cross-sectional view for explaining an optical switch that is a conventional example.

FIG. 14 is a plan view for explaining an optical switch that is a conventional example.

FIG. 15 is a perspective view for explaining an optical switch which is a conventional example.

[Explanation of symbols]

1A 1B 1C 1D 1E 1F 1G 2A 2
B 2C optical fiber, 2 reflection mirror,
3 optical paths, 4 9A 9B magnetic coils,
5 magnetic film, 6A 6B optical fiber fixed holder, 7 permanent magnet, 8 drive unit,
10 cases.

Claims (5)

[Claims] 1. An optical switch for switching an optical path from one of the two output optical fibers to the other by branching the optical path of the light beam from the incident optical fiber by a reflection mirror. The optical switch is characterized in that the distance between the reflection mirror and the reflection mirror and the distance between the output optical fiber and the reflection mirror are different. 2. The optical switch according to claim 1, wherein the incident beam angle from the incident optical fiber to the reflection mirror is 10 ° or less. 3. The rotation angle of the reflection mirror is 10 ° or less, and the angle between the two output optical fibers and the reflection mirror is twice the rotation angle of the reflection mirror. The optical switch according to any one of 1 or 2. 4. The light beam from N optical fibers for incidence is incident on the reflection mirror, and N sets of two optical fibers for output are provided. Light switch. 5. The incident optical fiber according to claim 1 is used as an output optical fiber, and the output optical fiber according to claim 1 is used as an incident optical fiber.
5. The optical switch according to any one of 4 to 4.