JP2519787B2 - Optical path switching circuit with attenuation function - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical path switching circuit that is incorporated in, for example, an optical signal processing device and selectively switches a traveling direction of light to a straight traveling direction or a right-angled traveling direction. The present invention relates to an optical path switching circuit with an attenuation function that attenuates only light that passes through a designated optical path.

[Prior Art] In recent years, an optical communication system using an optical signal in addition to a conventional electric signal as an information transmission medium has been put into practical use.
In the optical signal processing device incorporated in such an optical communication system, an optical path switching circuit having the same function as the signal switching circuit in a normal electric circuit is required.

As shown in FIGS. 4 (a), (b), (c), and (d), the basic switching function required of the optical switching circuit 5 is as follows. In order to smoothly transfer each optical signal, each signal processing unit 1-2, 1-3, 2-
It is necessary that the optical paths 1a, 1b, 2a, 2b, 3a and 3b connected to the optical fibers 1af, 1bf, 2af, 2bf, 3af and 3bf can be freely switched and connected between the two.

Further, in general, the light amount of the optical signal input to each of the signal processing units 1, 2, 3 and the optical path switching circuit 5 is often not constant. For example, each optical fiber (1af, 1bf), (2af, 2bf), (3af, 3b
Since the lengths of f) are not equal as shown in FIG. 5, the light quantity (level) in the optical signal passing through each optical fiber is not constant, and by switching the optical path, the signal processing units 1, 2, The level of the optical signal exchanged between the three will fluctuate.

On the other hand, the light amount loss of the optical signal allowed in the optical fiber has a certain allowable range determined by the optical output of the transmitting unit and the light receiving sensitivity of the receiving unit in each of the signal processing units 1, 2, and 3. That is, if the length of the optical signal path formed by the combination of the optical fibers 1af to 3bf formed between the signal processing units 1, 2 and 3 is too long, the optical signal is attenuated and cannot be received. On the other hand, if it is too short, the optical signal at the receiving section is too strong, which causes problems such as destruction of the light receiving element.

When designing the optical path switching circuit 5, it is necessary that the amount of light in the optical signal path formed between the signal processing units satisfies the above-mentioned allowable range, no matter how the optical path is switched. For example, in the optical path switching device shown in FIG. 5, the signal processing unit 3
Since the optical fibers 3af, 3bf connected to the signal processing unit 1 and 2 are very long compared to the optical fibers 1af, 1bf, 2af, 2bf connected to the other signal processing units 1 and 2, they are formed between the signal processing units 1 and 2. Optical fiber 1
The light quantity loss in the optical signal path using af, 1bf, 2af, 2bf is
Optical fibers 2af, 2bf, 3af, 3 formed between the signal processing units 2 and 3
Compared with an optical communication path using bf and an optical communication path using optical fibers 3af, 3bf, 1af, 1bf formed between signal processing units 3 and 1, the light amount loss is extremely small. Therefore, in FIG. 5, the light amount loss does not exceed the upper limit of the allowable range in the optical communication path between the signal processing units 1-3 or 2-3, and the optical communication between the signal processing units 1-2. It is necessary that the light amount loss on the road does not fall below the lower limit of the allowable range.

In order to satisfy such a requirement, it has been proposed to insert an attenuator 13 into the optical fibers 2af and 2bf having the larger amount of input light, as shown in FIG. This damping device 13
Is composed of four pairs of terminals and two optical attenuators 13a and 13b selectively inserted between the terminals. And the sixth
When an optical communication path is formed between the signal processing units 1 and 2 as shown in FIG. 3A, the optical attenuators 13a and 13b are connected to the optical fibers 2af and 2a, respectively.
By inserting into bf, each optical fiber 1af, 2bf, 2af,
The light amount of the pair of optical communication paths configured by 1bf is set to be lower than the upper limit value of the allowable range.

Further, when forming an optical communication path between the signal processing units 2 and 3, it is not necessary to further increase the light amount loss of each optical communication path. Therefore, as shown in FIG. The optical attenuators 13a and 13b of 13 are removed from the optical fibers 2af and 2bf. Further, as shown in FIG. 6 (d), when the signal processing unit 1 and the signal processing units 2 and 3 are respectively connected by one optical communication path, an optical fiber connected to the signal processing unit 1 is used. The optical attenuator 13a is inserted only in 2af, and the optical attenuator 13b is not inserted in the optical fiber 2bf connected to the signal processing unit 3. Note that, as shown in FIG. 6 (c), when forming an optical communication path between the signal processing units 1 and 3, the attenuator 13 is not directly related.

As described above, by using the attenuator 13, it is possible to control each light amount of each optical signal path formed between the signal processing units 1, 2, and 3 within a certain allowable range.

[Problems to be Solved by the Invention] However, each of the optical attenuators 13a and 13b of the attenuator 13 is
The optical path switching device that selectively interposes on the optical fibers 2af and 2bf connected to the individual signal processing units 2 still has the following problems. That is, each time the optical path switching circuit 5 is switched to change the optical communication path formed between the signal processing units 1, 2 and 3, the optical attenuators 13a and 13b are connected to the optical fibers 2af and 2bf. It is necessary to insert and leave. Therefore, the entire switching operation becomes complicated. Further, it is conceivable to automate the inserting / retracting operation of the optical attenuators 13a and 13b, but in this case an operating device is required, which complicates the entire optical path switching device and increases the overall size of the device.

As described above, if the attenuator 13 is separately provided, the operation is complicated, the number of parts is increased, the entire device for switching the optical path becomes large, and it is not preferable from the viewpoint of economical efficiency and reliability.

The present invention has been made in view of the above circumstances, and by attaching a light attenuating member to a predesignated optical path switching element, each optical signal is formed between signal processing units without separately providing an attenuator. An object of the present invention is to provide an optical path switching circuit with an attenuation function, which can always control each light quantity of an optical communication path within a certain allowable range, improve operability, and simplify the structure.

[Means for Solving the Problems] In order to solve the above problems, an optical path switching circuit with an attenuation function according to the present invention includes a first optical path group formed of a plurality of optical paths arranged on an arbitrary plane and parallel to each other. A second optical path group, which is arranged on a plane and is orthogonal to each optical path of the first optical path group and is composed of a plurality of optical paths parallel to each other, and each optical path of the first optical path group and the second optical path group. A plurality of optical path switching elements having a reflecting surface which is selectively inserted / retracted at each intersection with each optical path and which selectively switches the direction of light guided in each optical path to a straight direction or a right angle direction, and the plurality of optical path switching elements. Of these, a light attenuating member that is provided in a predetermined optical path switching element and that attenuates the amount of light reflected by the reflecting surface is provided.

[Operation] In the optical path switching circuit configured as described above, each optical path of the first optical path group and each optical path of the second optical path group intersect each other at a right angle. An optical path switching element is arranged at each intersection. The optical path switching element selectively switches the direction of the light guided through each of the optical paths to a straight traveling direction or a right angle direction. Therefore, for example, it is possible to switch the light input from the arbitrary signal processing unit to the optical path of the optical path switching circuit to the optical path connected to another arbitrary signal processing unit.

In addition, since the optical path switching element designated in advance is provided with the light attenuating member for attenuating the amount of light reflected by the reflecting surface, the optical path switching element passes through the optical path whose traveling direction is switched to the orthogonal direction. Only light is attenuated. Therefore, the light quantity of the optical signal path between the signal processing sections formed by using the optical path switched at right angles by the optical path switching element to which the optical attenuating member is attached, that is, the light quantity of the optical signal path where the light quantity of the optical signal is strong is changed to the corresponding light path switch It becomes possible to approximate the light amount of the other long optical signal path without using the element, that is, the light amount of the light signal path where the light signal intensity is weak.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a schematic configuration of an optical path switching circuit with an attenuation function of the embodiment. The same parts as those in FIG. 4 are denoted by the same reference numerals. The optical path switching circuit 20 of this embodiment includes optical fibers 1af, 1bf, 2af, 2bf, 3 between the three signal processing units 1, 2, 3 respectively.
An optical path switching circuit capable of arbitrarily switching each optical signal path constituted by af, 3bf and each optical path 1a, 1b, 2a, 2b, 3a, 3b.

The optical signal output from the signal processing unit 1 is the optical fiber 1af
The optical signal input to the optical path 1a in the optical path switching circuit 20 via the optical path switching circuit 20 and output from the optical path 1b in the optical path switching circuit 20 is input to the signal processing unit 1 via the optical fiber 1bf. In addition, the optical signal output from the signal processing unit 2 is the optical fiber 2a.
The optical signal input to the optical path 2a in the optical path switching circuit 20 via f and output from the optical path 2b in the optical path switching circuit 20 is input to the signal processing unit 2 via the optical fiber 2bf. Furthermore, the optical signal output from the signal processing unit 3 is an optical fiber.
The optical signal input to the optical path 3a in the optical path switching circuit 20 via 3af and output from the optical path 3b in the optical path switching circuit 20 is input to the signal processing unit 3 via the optical fiber 3bf.

In the optical path switching circuit 20, the optical paths 1a and 3b are arranged on the same plane and on one straight line. Similarly optical path 3a, 1
b is arranged on the same plane and on one straight line.
The optical paths 1a, 1b and 3a, 3b are arranged parallel to each other. Thus, the optical paths 1a, 1b, 3a and 3b form a first optical path group. The optical paths 2a and 2b are arranged on the optical paths 1a, 1b, 3a and 3b in the same plane and at right angles. Therefore, the optical paths 2a, 2
b constitutes the second optical path group.

Further, the optical path switching elements 21a, 2 are provided at the respective intersections of the optical paths 1a, 1b, 3a, 3b of the first optical path group and the optical paths 2a, 2b of the second optical path group.
1b, 21c, 21d are arranged. Each optical path switching element 21a
Reference numerals 21 to 21d are, for example, prisms or mirrors whose reflecting surface 22 has an inclination angle of 45 ° with respect to the optical path, and these optical path switching elements 21a to 21d are inserted at the respective intersections by a driving mechanism (not shown). -By retreating, the direction of the light guided through each optical path is selectively switched between a straight direction and a right angle direction. That is, when one of the optical path switching elements 21a to 21d is inserted into the corresponding intersection, the light guided to the corresponding intersection is bent in the direction perpendicular to the reflection surface 22 of the optical path switching element. Further, when the optical path switching element is withdrawn from the corresponding intersection, the light guided to the corresponding intersection does not hit the reflecting surface 22 and therefore goes straight.

Of the four optical path switching elements 21a to 21d composed of the prisms and mirrors, the two optical path switching elements 21b and 21c have a reflective surface 22 as shown in FIGS. 2 (a) and 2 (c). A light attenuating member 23 made of a metal deposition or a dielectric film that blocks a part of light is formed. Further, as shown in FIGS. 2B and 2D, the light attenuating member 23 may be formed on the transmitting surface. Further, as shown in FIG. 2 (e), the light switching elements 21b and 21c themselves may be composed of the light attenuating member 23. That is,
Only the light quantity of the light whose traveling direction is switched to the perpendicular direction by the two designated optical path switching elements 21b and 21c is forcibly attenuated.

The operation of the optical path switching circuit with the attenuation function configured as described above will be described with reference to FIG. In addition, each signal processing unit 1, 2,
Optical fibers (1af, 1bf), (2af, 2b) connected to 3
It is assumed that the relationship between the lengths of f) and (3af, 3bf) is the same as in FIG. 5 described above.

First, when the optical path switching elements 21a to 12d are not inserted at the intersections at all, as shown in FIG.
A pair of optical communication paths (1af-1a-3b-3bf), (3af-3a)
−1b−1bf) is formed. In this case, the light on this optical communication path is not forcibly attenuated.

Further, when the optical path switching elements 21a and 21d are inserted at the intersections, a pair of optical communication paths (2af-2a-3b-3bf), (3af-) are provided between the signal processing units 2 and 3 as shown in FIG. 3a-2b-2bf) is formed. Also in this case, the light on this optical communication path is not forcibly attenuated.

Furthermore, when the optical path switching elements 21b and 21c are inserted at the intersections,
As shown in FIG. 3C, a pair of optical communication paths (1af-1a-2b-2bf) and (2af-2a-1b-1bf) are formed between the signal processing units 1 and 2. In this case, each light of the pair of optical communication paths is forcibly attenuated by the attenuating member 23 on the reflecting surface 22 of the optical path switching element 21b, 21c.

Furthermore, when the optical path switching elements 21c and 21d are inserted at the intersections,
As shown in FIG. 3D, one optical communication path (1af-1a-2b-2bf) is formed between the signal processing units 1 and 2, and another optical communication path is provided between the signal processing units 3 and 1. Book optical communication path (3af-3a-1b-1b
f) is formed. In this case, the light on the optical communication path between the signal processing units 1 and 2 is forcibly attenuated by the attenuating member 23 of the reflecting surface 22 of the optical path switching element 21c, but the light on the optical communication path between the signal processing units 3 and 1 is Light is not forcibly attenuated.

As described above, by inserting / retracting the optical path switching elements 21a to 21d into / out of the corresponding intersections, optical signals can be arbitrarily transmitted / received among the signal processing units 1, 2 and 3.

In addition, among the optical communication paths formed between the signal processing units 1, 2 and 3, the optical communication path is short, that is, the light formed between the signal processing units 1 and 2 where the light intensity of the optical signal is strong. The light on the communication path is the light attenuating member 23 attached to the optical path switching elements 21b and 21c.
Is forcibly damped by. As a result, the amount of light that is forcibly attenuated is close to the amount of light in the optical communication path that is formed between the signal processing units 1 and 3 and between 2 and 3 where the optical communication path is long, that is, the optical signal is weak. To do. Therefore, no matter how the optical path switching device 4 switches the optical communication path between the signal processing units 1, 2, and 3, the light quantity in each optical communication path can be controlled within the allowable range.

Thus, by providing the light attenuating member 23 only for the specific optical path switching elements 21b and 21c, it is not necessary to separately provide a dedicated attenuating device 13 unlike the conventional device. Therefore,
The entire optical path switching device can be made compact and lightweight with a simple structure.

Further, since the light is automatically forcibly attenuated when the optical path switching operation is executed, the operability is significantly improved.

[Effects of the Invention] As described above, according to the optical path switching circuit with an attenuation function of the present invention, an optical path switching element for switching the direction of light to a straight direction or a right angle direction is provided at each intersection of mutually orthogonal optical paths. Thus, it has an optical path switching function of arbitrarily switching the optical path between the signal processing units with a simple configuration. In addition, since the optical attenuation member is provided in the optical path switching element designated in advance, the light amount loss of each optical communication path formed between the signal processing units can always be kept within a certain allowable range without providing an additional attenuation device. Can be controlled. Therefore, it is possible to realize the most appropriate scale from the viewpoints of operability, economical efficiency, and reliability, and the minimum necessary functions such as optical path switching and light quantity control with one circuit.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a schematic configuration of an optical path switching circuit with an attenuation function according to an embodiment of the present invention, FIG. 2 is a perspective view and a sectional view showing an optical path switching element provided with an attenuation member, and FIG.
FIG. 4 is a diagram showing optical path switching for explaining the operation of the circuit of the embodiment, FIG. 4 is a diagram showing optical path switching required for a general optical path switching circuit, and FIG. 5 is an optical path switching circuit and each signal processing. FIG. 6 is a diagram showing a connection state with a unit, and FIG. 6 is a diagram showing an optical path switching and an optical attenuation function required for a general optical path switching device. 1,2,3 …… Signal processing unit, 1a, 1b, 2a, 2b, 3a, 3b …… Optical path, 20
...... Optical path switching circuit, 21a, 21b, 21c, 21d ...... Optical path switching element, 22 ...... Reflecting surface, 23 ...... Attenuation member.

Claims (1)

(57) [Claims] 1. A first optical path group (1a, 1b, 3a, 3b) arranged on an arbitrary plane and comprising a plurality of optical paths parallel to each other, and the first optical path group arranged on the plane. A second optical path group (2a, 2b) that is orthogonal to each optical path and is parallel to each other, and each optical path of the first optical path group and each optical path of the second optical path group. A plurality of optical path switching elements (21a, 21b, 21c, 21) each having a reflecting surface (12) inserted / retracted at the intersection and selectively switching the direction of light guided through each of the optical paths to a straight direction or a right angle direction.
d) and a light attenuating member (23) provided in a predetermined optical path switching element among the plurality of optical path switching elements and attenuating the amount of light reflected by the reflecting surface. Optical path switching circuit.