JPH0475013A - Optical switch - Google Patents

Abstract

PURPOSE:To facilitate the manufacture, to reduce the cost, and to stably decrease the insertion loss by propagating waveguide light to be processed in plane waveguides formed on one substrate and not putting the plane optical waveguides in mechanical operation at all. CONSTITUTION:This optical switch consists principally of the couple of plane optical waveguides 6a and 6b which are formed on the substrate 2 while having their front end opposite each other and a movable total reflecting mirror 5. Namely, the optical waveguides 6a and 6b in the switch are all formed on the same substrate 2, so optical axis adjustments need not be made between the waveguides 6a and 6b when the optical switch is assembled. The total reflecting mirror 5 needs only to be parallel to the mutually opposite end surfaces of the plane optical waveguides 6a and 6b at the time of insertion, and their initial positions, movement quantities, and positions at movement destinations are easily controlled. Consequently, the optical switch is formed in an easy manufacturing process and reduced in the manufacture cost; and the propagation loss is small and the insertion loss is decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to optical switches. More specifically, the present invention relates to an optical switch configured using a planar optical waveguide, and in particular to a novel optical switch configuration that can be advantageously applied to forward path switching for optical communication. .

2. Description of the Related Art As optical communication technology advances, various complex optical signal transmission systems are being constructed.

One of the optical devices most frequently used in such optical signal transmission systems is an optical switch, and in particular, an optical switch that has the function of switching optical transmission lines is indispensable in the configuration of any optical system.

FIGS. 3(a) and 3(b) are diagrams showing an example of the configuration of a known optical switch and its operation, as described in Paper B660 published by the Institute of Electronics, Information and Communication Engineers in 1988.

As shown in the figure, this optical switch includes a pair of blocks 33 and 34 on which the front ends of three optical fibers 31a to 31C and 32a to 32c are respectively mounted. 1
The pairs of blocks are arranged adjacent to each other, and usually one is fixed and the other is configured to be movable in the direction indicated by the arrow in the figure by an actuator (not shown). Further, the respective fibers 31a to 31C and 32a to 32a are arranged at equal intervals on the blocks 33 and 34, respectively, and as shown in FIG.
When the optical fibers 3 and 34 are directly facing each other, the optical fiber 31a
and 32a, 31b and 32b, and 31c and 32C are arranged so as to be optically coupled to each other.

In addition, in the optical switch shown in FIG. 3, the optical fiber 31a
The rear end and the rear end of the optical fiber 32c are coupled by an optical fiber 35 for connection. In addition, the optical fiber 31
The rear end of b connects the optical fiber 3 to the input port from the optical transmission line.
The rear ends of 1C are respectively coupled to optical transmitters 36,
On the other hand, the rear end of the optical fiber 32a is coupled to an optical receiver 37, and the rear end of the optical fiber 32b is coupled to an output port for an optical transmission line.

FIG. 3(a) shows the normal mode state of this optical switch. That is, in this state, the propagating light that has entered from the input port is input to the receiver 37 via the optical fibers 31b and 32a. Further, the optical signal emitted from the transmitter 36 is sent to the output port via the optical fiber 31C and the optical fiber 32b. Therefore, a device (not shown) including the receiver 36 and transmitter 37 is bidirectionally coupled to an optical transmission path (not shown) connected to the input port and the output port.

On the other hand, FIG. 3('b) shows the bypass mode of this optical switch. That is, when either block 33 or 34 moves and the two face each other directly, optical fibers 31a and 32a, 31b and 32b, and 31C and 32C are coupled, respectively. Therefore, in this state, the propagating light injected from the input port is transmitted through the optical fibers 31b and 32.
directly to the launch boat via b.

On the other hand, the optical signal output from the transmitter 36 is transmitted through the optical fiber 3.
1c, 32535.31a and 32a directly to the receiver 37. Therefore, the device including the receiver 36 and the transmitter 37 is disconnected from the optical transmission line (not shown) connected to the input port and the output port.

By operating as described above, this optical switch is used for operations such as connecting or disconnecting a specific node from the bus in an optical LAN system, for example.

4(a) and 4(b) are diagrams showing the configuration and operation of an optical switch described in Paper C492 of the Institute of Electronics, Information and Communication Engineers in 1988, as another example of a conventional optical switch. .

The state of the normal mode is shown in FIG. 4(a), and the state of the switching mode is shown in FIG. 4(a).

As shown in the figure, this optical switch mainly consists of two pairs of optical fibers 41a and 42a and 41b and 42b facing each other, and a square prism 43 disposed between these two pairs of optical fibers. It is configured. Note that the prism 43 is configured to be rotatable by an actuator (not shown).

FIG. 4(a) is a diagram showing the normal mode of this optical switch, in which each optical fiber 41a, 41b,
The end face of the prism 43 is configured to be perpendicular to the optical axis at the ends of the prisms 42a and 42b. Therefore, in this state, the eight beams emitted from one of the optical fibers, for example 41a and 41b, enter the end face of the prism 43 at right angles and are directly injected into the opposing optical fibers 42a and 42b.

FIG. 4 (Company) is a diagram showing the switching mode of this optical switch. At this time, each optical fiber 41a, 41b, 4
With respect to the optical axis at the ends of 2a, 42b, the prism 4
3 is rotated so that its end face is rotated at 45°, and the output light emitted from the optical fibers 41a and 41b enters the end face of the prism 43 at an angle. Therefore, each emitted light is refracted when entering the prism 43 and when exiting the prism 43,
The connection state of the propagating light changes. That is, the optical fiber 41a
The emitted light is injected into the optical fiber 42b, and the output light from the optical fiber 4
The emitted light from 1b is injected into the optical fiber 42a.

Through the above-described operation, this optical switch can switch the connection state of two pairs of optical transmission lines.

FIG. 5 is a diagram showing a specific application example of the 2×2 optical switch as described above.

That is, FIG. 5 shows the basic configuration of a loop-type optical LAN, and this optical LAN includes a loop-shaped optical fiber bus 100 and a plurality of nodes 100a.

100b and 100C are connected to each other. Here, each of the nodes 100a, 100b, and 100C includes an optical transmitter ○TX and an optical receiver ORX connected to the bus 100 via a 2x2 optical switch O8W.

When each node of the optical LAN configured as described above is operating normally, the bus 10 is
0 is connected to an optical receiver ORX and an optical transmitter OTX via an optical switch O3W. However, if an error occurs in any node, that node will
In order to prevent the 00 loop from being interrupted, it is necessary to disconnect that node from the bus 100 by the optical switch O8W, as shown by the dotted line in the figure. The 2×2 optical switch shown in FIGS. 3 and 4 is constructed to realize such a function.

Problems to be Solved by the Invention The conventional optical switch shown in FIG. 3 is configured to change the coupling state by mechanically displacing a block holding an optical fiber. Therefore, when manufacturing the block, the positioning and displacement of the block must be controlled very precisely in order to achieve the desired function. Also,
In the optical switch shown in FIG. 4, as well as the shape and optical quality of the prism itself, its arrangement and amount of rotation must be controlled with extremely high precision. Optical switches that require such precise machining and assembly end up being extremely expensive.

In addition, with conventional optical switches that mechanically operate optical devices that propagate optical signals, the connection state of the transmission line changes slightly depending on the position of the block or prism, making it difficult to maintain low insertion loss. .

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and provide a novel optical switch that is easy to manufacture and inexpensive, and has a stable and low insertion loss. .

According to the present invention, first right and second end faces draw straight lines parallel to each other, and a third end face each draws a part of a paraboloid.
and a fourth end surface, a pair of first and second planar optical waveguides, each first end surface facing each other in parallel and formed on the same plane; a total reflection mirror that can be inserted between the end faces in parallel to the first end face; an input port and an output port are coupled to each second end face of the first and second planar optical waveguides, respectively; In the first and second optical waveguides, the third end face is arranged at a predetermined angle that is not perpendicular to the first and second end faces. corresponds to the narrower region sandwiched between the first end surface and the second end surface on a paraboloid having a long axis with an angle of and a focus on the second end surface. : The fourth end surface has a shape that is line symmetrical to the third end surface about a predetermined straight line that intersects both the first and second end surfaces at right angles; The planar optical waveguide and the second planar optical waveguide have the same shape, and are arranged symmetrically about a straight line parallel to the first end surface located between the two first end surfaces; Each of the first and second planar optical waveguides has a straight line passing through the intersection of the first end surface and the third end surface of one of the planar optical waveguides and parallel to the long axis of the parabola defining the third end surface of the other planar optical waveguide. The interval between each other is set so as to intersect with the first end face of the planar optical waveguide; the recessed part or the convex part formed on each second end face of the first and second planar optical waveguides is
An output boat or an input port connected to the concave portion or convex portion is configured to be coupled to each focal point of a paraboloid defining a third end surface and a fourth end surface of each planar optical waveguide; The reflection mirror has total reflection characteristics on both sides, and has a first position where it shields a region sandwiched between the first end faces of the first and second planar optical waveguides, and a second position where the reflection mirror has a total reflection property. The second waveguide retracts from the area sandwiched between the first end faces of the planar optical waveguide.
An optical switch is provided that is configured to be movable between positions.

-Operation The optical switch according to the present invention has a unique configuration consisting of a pair of planar optical waveguides having a predetermined shape and one total reflection mirror.

That is, the main feature of the optical switch according to the present invention is that it uses a planar waveguide whose side surface has an end face shaped like a paraboloid. As detailed below,
In the optical switch according to the present invention, guided light is injected into a planar optical waveguide having such a shape from a port coupled to a position corresponding to the focal point of the paraboloid. Therefore,
Light that propagates within the planar optical waveguide and is reflected by the parabolic end face becomes a light ray parallel to the long axis of the paraboloid formed by this end face. Such parallel light rays are emitted from the end face of each planar optical waveguide on the opposite side to the incident side, and are again injected into the facing planar optical waveguide having the same shape.

Here, the parallel light beam injected into the facing second planar optical waveguide propagates as a light beam parallel to the long axis of the paraboloid formed by the end face of the second planar optical waveguide.

Therefore, the parallel light rays reflected by the parabolic end face of the second planar optical waveguide converge at the focal point of the parabola. In this way, propagating light can be extracted from the port coupled to the focal point of this second planar optical waveguide. In the process described above, light injected into the focal point of a parabola in one planar optical waveguide is emitted from the symmetrical focal point of the parabola in the other planar optical waveguide.

Further, when a total reflection mirror is inserted between the end faces of the pair of planar optical waveguides, the injection light emitted from one of the planar optical waveguides is again injected into the planar optical waveguide as a parallel beam. The parallel light beam reinjected into the original planar optical waveguide is reflected by the parabolic end face opposite to the first reflected parabolic end face, and converges at the focal point of the parabola. Therefore, light injected from one port is emitted from the port connected to the other focal point.

Due to the above-described effects, the optical switch according to the present invention allows light incident on one port of one planar optical waveguide to be connected to the other planar optical waveguide, depending on whether or not a total reflection mirror is inserted. It is possible to switch between emitting light from a port and emitting light from the other port of the planar optical waveguide where it was first implanted.

Furthermore, a 2×2 switching optical switch can be constructed by connecting a port to a pair of focal points of each optical waveguide and using a double-sided total reflection mirror to be inserted.

In such an optical switch according to the present invention, all the optical waveguides in the switch are formed on the same substrate, so there is no need to adjust the optical axis between the waveguides during assembly.

Further, the total reflection mirror only needs to be parallel to the mutually opposing end surfaces of each planar optical waveguide when inserted, and its initial position, amount of movement, and position at the destination can be easily controlled.

Therefore, compared to conventional optical switches, it can be manufactured through a much easier manufacturing process, and its manufacturing cost is significantly reduced. Furthermore, since each optical waveguide is a planar optical waveguide integrally formed on one substrate, propagation loss is small, resulting in an optical switch with low insertion loss.

Further, in the optical switch according to the present invention, the rear end of each planar optical waveguide is provided with a recess or a projection for connecting an input port or an output port. Therefore, for example, installation can be made extremely easily by attaching a ferrule or connector to the end of the optical fiber used as an input port or an output hoard. Furthermore, since light enters or exits from the focal point of the parabola for each optical waveguide whose side end face is shaped like a parabola, it is tolerant of the precision of alignment of each optical fiber, making it less practical. Extremely high.

Note that the shapes of the pair of planar optical waveguides and the substrate that supports them can be selected as appropriate depending on the application, but when no total reflection mirror is inserted, Since it is necessary to propagate the light beam to the optical waveguide, care must be taken to ensure that the distance between the two does not become excessive. Furthermore, light leaks to the outside through the gap between the pair of planar optical waveguides, so from this point of view as well, it is preferable that the distance between the two be narrow.

Hereinafter, the present invention will be described in more detail with reference to the drawings, but the following disclosure is only one embodiment of the present invention, and does not limit the technical scope of the present invention in any way.

Embodiment FIG. 1 is a diagram showing a specific example of the configuration of an optical switch according to the present invention.

As shown in the figure, this optical switch includes a pair of planar optical waveguides 6a formed on a substrate 2 whose front ends face each other.
and 6b, and a movable total reflection mirror 5. In addition, at the rear end of each of the planar optical waveguides 6a and 6b, as shown in the X-X horizontal cross-sectional shape in FIG. A pair of recesses or protrusions are formed to fit with the fiber connector. That is, by connecting an optical fiber connector so as to fit into this recess or projection, an input port or an output port is coupled to a predetermined position of the planar optical waveguides 6a and 6b, which will be described later. Further, in the center of the substrate 2, each planar optical waveguide 6a,
A groove 7 is formed by removing the substrate 2 between the end faces of the groove 6b and is wide enough to accommodate the total reflection mirror 5.

The total reflection mirror 5 has total reflection characteristics on both sides and is configured to be movable within the groove 7.

That is, the total reflection mirror 5 can take a first position where it avoids the area between the end faces of the planar optical waveguides 6a and 6b facing each other, and a second position where it completely blocks the space between them. It is configured. The total reflection mirror 5 is configured to be parallel to the end surfaces of the planar optical waveguides 6a and 6b at least in its second position.

FIGS. 2(a), 2(a), 2(c) and 2(a) are diagrams illustrating the detailed configuration and operation of the optical switch shown in FIG. 1. FIG.

As shown in FIG. 2(a), each of the planar optical waveguides 6a and 6b has the same shape, and herein, the planar optical waveguide 6a will be explained. Furthermore, as described above, a pair of recesses or protrusions that fit into an optical fiber connector are formed at the rear end of each planar waveguide.

The horizontal cross-sectional shape of the planar optical waveguide 6a is parallel to each other.
and second end faces 61a and 62a, and third and fourth end faces 6 each drawing a part of a parabola as described later.
3a and 64a. The shape of the third end surface 63a is such that Cy=ax2) with respect to the y-axis that has a predetermined angle with respect to the first and second end surfaces 61a and 62a, and the X-axis that is perpendicular to this y-axis. The focal point of this parabola is F
, are formed so as to be located on the second end surface 62a. Further, the fourth end surface 64 is connected to the first and second end surfaces 61.
The shape is symmetrical about the third end surface 63a with respect to the straight line A that is perpendicular to 62a. Therefore, the focal point Fl' of the parabola drawn by the fourth end surface 64a is also located on the second end surface 62a. Note that the optical fiber la serves as an input port or an octet port.

and 1b have focal points F1, F,
“They are each connected to

The second planar optical waveguide 6b is arranged line-symmetrically with the first planar optical waveguide 6a with respect to the total reflection mirror 5 inserted therebetween, and has exactly the same shape.

Further, the optical fibers IC and 1d, which serve as the input port or the output port for the second planar optical waveguide 6b, also have the focal points F 2 and F of the parabola drawn by the end surfaces 63b and 64b.
2'.

Incidentally, each of the planar optical waveguides 6a and 6b may be formed, for example, by exchanging B' and Na' by an ion exchange method using optical glass BK7, and then forming the grooves 7 by an ion milling method or a grinding method. At this time, the shape of the waveguide can be controlled by utilizing phosphorography technology and using a mask to limit the location where ions are exchanged.

The thickness of the planar optical waveguides 6a and 6bt17) is preferably made to match the core diameter of the optical fibers la, lb, lc and 1d to be coupled. Furthermore, it is preferable that the input/output end surfaces of the planar optical waveguides 6a and 6b be coated with anti-reflection coating as described above. Specifically, it is preferable to apply an Mgf thin film formed by vapor deposition or sputtering. can. The total reflection mirror 5 can be made of a multilayer film of SiC2, TiO2, or the like.

The optical switch configured as described above operates as follows.

FIGS. 2A and 2B are diagrams showing the propagation state of the injected light when the total reflection mirror 5 is not inserted between the planar optical waveguides 6a and 6b. In addition, each planar optical waveguide 5a, 5b has the following:
A pair of optical fibers 1a) lb, 1c, ld are each connected as an input port or an output port.

As shown in the figure, among the light injected from the optical fiber 1a, which is the input port, into the planar optical waveguide 6a, the end face 63a
The propagating light reflected by the long axis of the parabola drawn by the end face 63 (
y-axis) and is emitted from the end surface 61a. This parallel light beam enters the planar optical waveguide 6b from the end face 61b, is reflected by the end face 64b, converges at the focal point F2°, and is extracted from the optical fiber 1d. Although not shown in the figure, the optical fiber 1b and the optical fiber 1c are also
are similarly connected. That is, the optical switch in the state shown in FIG. 2 et al. forms the following two-system coupled state.

FIG. 2(C) shows that in the optical switch shown in FIG.
6 is a diagram showing the function of an optical switch when a total reflection mirror 5 is inserted between a pair of planar optical waveguides 6a and 6b. FIG.

As shown in the figure, among the light injected into the planar optical waveguide 6a from the optical fiber 1a, which is the input port, the propagating light reflected at the end face 63a is transmitted along the long axis (y) of the parabola drawn by the end face 63.
The light beam is emitted from the end surface 61a as a light beam parallel to the axis).

This parallel light beam is once emitted from the end surface 61a of the planar optical waveguide 6a, is reflected by the total reflection mirror 5, and is reflected by the end surface 61a of the planar optical waveguide 6a.
From 1a, the light enters the planar optical waveguide 6a again. At this time, the reflected light incident on the planar optical waveguide 6a becomes a ray parallel to the long axis of the parabola drawn by the end surface 64a. Therefore,
When this parallel ray is reflected by the end face 64a, the focus F,
1 and is extracted from the optical fiber 1b.

Note that when both surfaces of the total reflection mirror 5 have total reflection characteristics, the optical fibers IC and ld are similarly coupled in the planar waveguide 6b. That is, the optical switch in the state shown in FIG. 2 et al. forms the following two-system coupled state.

Through the above-described operation, the optical switch shown in FIG. 1 realizes a 2×2 switching function.

Note that each end face 61a of the pair of planar optical waveguides 6a and 6b
and the interval β between 61b and 61b is the total reflection mirror 5 inserted between them.
The interval can be selected as appropriate depending on the dimensions, etc., but as shown in Fig. 2(d), the interval! If it is too large, optical coupling between the two will not be formed, so it is preferable to design it to be as narrow as possible.

As described in detail, the optical switch according to the present invention is composed of a pair of planar optical waveguides having a unique shape and a total reflection mirror. Here, the guided light to be processed propagates in a planar waveguide formed on one substrate, and this planar optical waveguide does not perform any mechanical operation. Therefore, its function and insertion loss do not depend on assembly accuracy and do not require precise adjustment, so that manufacturing man-hours and manufacturing costs can be reduced.

Furthermore, the light transmission path within the optical switch is a planar optical waveguide, and the number of times the light propagates to different media is small, so transmission loss is also reduced.

Furthermore, a concave or convex portion is formed on the input side or output side end face of each optical waveguide in order to facilitate the alignment of members such as optical fibers that will become the input port or output boat. Very easy to handle.

The optical switch according to the present invention having such characteristics can be advantageously used as an inexpensive and high-performance optical switch in a simple optical local area network and the like.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a specific configuration example of the optical switch according to the present invention, and FIG. FIG. 3(a) and (b) are diagrams showing a typical configuration example of a conventional optical switch and its operation, and FIG. 4(a) and FIG. ) is a diagram showing a configuration example of another conventional optical switch and its operation. FIG. 5 is a diagram showing an example of the configuration of an optical system using a 2×2 optical switch. [Main reference numbers] la, lb, lc, ld. 31a, 31b, 31c, 32a, 32b, 32c, 3
5.41a, 41b, 42a, 42b... Optical 7 fiber, 2... Substrate, 5... Total reflection mirror, 6a, 6b... Planar optical waveguide, 7... Groove, 33.34 ...Block, 36...Transmitter, 37...Receiver, 61a161b...First end face, 62a, 62b -...Second end face, 63a, 63b
-...Third end face, 64a164b...Fourth end face, 100...Optical fiber bus, 100a, 100b, 100c -...Node, ○
SW...2X2 optical switch, OTX...optical transmitter, ○RX...optical receiver

Claims (1)

[Claims] Defined by first and second end faces that draw straight lines parallel to each other, and third and fourth end faces that each draw a part of a paraboloid, and each first end face is a pair of first and second planar optical waveguides that face each other in parallel and are formed on the same plane; a total reflection mirror that can be inserted between the pair of first end faces in parallel to the first end face; an optical switch comprising: a concave portion or a convex portion configured to connect an input port and an output port to each second end face of the first and second planar optical waveguides; : In the first and second optical waveguides, the third end surface has a long axis having a predetermined angle that is not perpendicular to the first and second end surfaces, and is located on the second end surface. corresponds to the narrower region sandwiched between the first end face and the second end face on a paraboloid having a focal point; The first planar optical waveguide and the second planar optical waveguide have the same shape; and are arranged symmetrically about a straight line parallel to the first end face located between the two first end faces; each of the first and second planar optical waveguides The mutual spacing is set such that a straight line passing through the intersection of the first end surface and the third end surface of the waveguide and parallel to the long axis of the parabola defining the third end surface intersects the first end surface of the other planar optical waveguide. The concave portion or convex portion formed on each second end face of the first and second planar optical waveguides is such that the output port or the input port connected to the concave portion or convex portion of each of the planar optical waveguides is The total reflection mirror is configured to be coupled to each focal point of a paraboloid that defines a third end face and a fourth end face; both surfaces of the total reflection mirror have total reflection characteristics, and the first and second a first position that shields a region sandwiched between the first end surfaces of the planar optical waveguide, and a second position that retreats from the region sandwiched between the first end surfaces of the first and second planar optical waveguides. An optical switch characterized in that it is configured to be movable between the two.