JPH02199431A - Optical switch and optical network - Google Patents

Abstract

PURPOSE:To execute all operation modes, a self-diagnosis, etc., by one optical switch by forming a 3X3 optical switch and connecting its input and output terminals to two optical fibers and an optical receiver and an optical transmitter in a node. CONSTITUTION:Three optical waveguides T1 - T3 are formed on a substrate LN and then provided with waveguide nearby parts N1 - N3 which have electrode couples (E1 and E'1) - (E3 and E'3) to constitute the 3X3 optical switch SW. Further, two optical fibers (lines P and S) from adjacent nodes B' and D' and one optical fiber from the optical transmitter OS of a node A are connected to three optical input ports of the switch SW of, for example, one node A', and two optical fibers (lines P and S) to the nodes B' and D' and one optical fiber to the optical receiver are connected to the light output ports to constitute the optical network. This constitution enables one optical switch for each node to handle all network states such as a normal state, a stand-by ring switching, node by-passing, looping-back operation, the self-diagnosis, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is utilized in the configuration of an optical network, and in particular, in a dual ring type optical network, protection ring switching,
The present invention relates to an optical switch and an optical network that can perform all switching such as node bypass, loopback, and self-diagnosis.

[Conventional technology]

In order to facilitate understanding of the present invention, a failure countermeasure method for a ring type optical network will first be explained.

FIGS. 5(a) to 5(d) are explanatory diagrams of a ring-type optical fiber network such as a token ring or slotted ring in which nodes are connected in a ring shape with two optical fibers. In Figures 5(a) to (d), A, B, C and D
is a node, and P and S are normal and emergency lines, respectively. The subscripts I and O on lines P and S represent inputs to and outputs from the nodes, respectively. Inside the node, there are optical switches (SW),
It includes a data control circuit (MAC), an optical transmitter (O8), an optical receiver (OR), etc. The internal configuration of the node will be described later.

FIG. 5(a) shows a normal optical signal transmission state. The optical signal is sent to node A, using line P, as shown by the arrow.
B, C, and D are transmitted in this order.

Figures 5 and 5) show the state of optical signal transmission at the time of protection ring switching. If there is an abnormality such as a fiber break (x mark in the figure) on line P, the optical switch installed inside each node A, B, C, and D changes the optical path from P1→P0 to S1→So. , and the optical signal is transmitted using line S to nodes D, C1B, and A in this order (generally,
The transmission directions of optical signals on lines P and S are opposite directions).

FIG. 5(C) shows the state of optical signal transmission during node bypass. For example, if there is an abnormality in the data control circuit, optical transmitter, or optical receiver in node C (x mark in the diagram), the optical path is switched by an optical switch installed inside node C, and the abnormal node is bypassed. be done. This allows communication between other normal nodes to continue.

FIG. 5(d) shows the state of optical signal transmission during loopback. For example, due to a cable cut accident between nodes B and C, 2
When optical fiber lines P and S are both cut (marked with an x in the figure), the optical switches in nodes B and C will have an input of P1 at node B and an output of S1, and an output of S1 at node C. P.

It switches to a U-turn shape. At this time, the line S side of nodes A and D enters a node bypass state. As a result, the optical signal is sent to the same node A and BSC as in the normal mode.
, D.

Therefore, in the event of any failure, the optical path is set by the optical switch within each node so as to avoid the abnormal part. Therefore, optical switches are one of the essential components in order to realize a ring-type optical fiber network that is highly reliable against failures.

Until now, there has been no single optical switch that can satisfy all of the above functions, and the closest configuration to the present invention uses two 2X
There was one that combined a type 2 light switch. Its configuration and operation will be explained below.

Figure 6 shows a state in which a conventional optical switch is incorporated into a node (
Shown in a) to (d). In FIGS. 6(a) to (d),
SWl and SW2 are conventional optical switches, MAC is a data control circuit, OR is an optical receiver, and O8 is an optical transmitter. The optical switches SW1 and SW2 have the following two modes.

(1) Parallel mode: An optical signal input from the optical input port 11 is output to the optical output port 01, and an optical signal input from the input port is output to the optical output port 02.

(2) Exchange mode: The optical signal input from the optical input port 11 goes to the optical output port 02, and the optical signal input from the optical input port I2 goes to the optical output port 0. Output to.

Although many structures of optical switches SW1 and SW2 have been proposed so far, the problems described below are the same regardless of the structure. For this reason, in FIGS. 6(a) to 6(d), the functions of the optical switches SWI and SW2 are only indicated by arrows.

FIG. 6(a) shows a normal optical signal transmission state. Human resources department P
1 or the optical signal is input from SWl ■2 as shown by the arrow.
→02→OR→I2 of os-sw2→02, and is output from the output section P0.

FIG. 6 et al.) are the standby ring switching state or bypass state. If there is an abnormality such as a fiber break on line P, optical switches SWI and SW2 switch from parallel mode to switching mode, and the optical signal is transmitted using line S (protection ring switching state). If there is an abnormality in the optical receiver OR, optical transmitter O8, or data control circuit MAC of the node while transmitting an optical signal using line P, the state shown in Fig. 6(b) can be applied. , the abnormal part is bypassed (node bypass state). Similarly, if there is an abnormality while the line S is in use, the optical switches SW1 and SW2 go into parallel mode and the abnormal part is bypassed, as shown in FIG. 6(a).

FIGS. 6(C) and 6(d) show the state during loopback. For example, the human power section Sx and the output section P. When the two optical fibers on the side are both cut, as shown in FIG. 6(C), the optical switch SWI is in the parallel mode, and the optical switch SW2 is in the parallel mode.
is in the exchange mode, and the optical signal manually input from the human power section P1 is changed to ■2→02→OR→○ of the optical switch SW1.
It is transmitted as I2 of S-+SW2→0,→So. Alternatively, if the two optical fibers on the output section S0 and input section P1 sides are both cut, as shown in FIG. 6(d), the optical switch SW1 will be in the exchange mode and the optical switch SW2 will be in the parallel mode. , the optical signal input from the input section S1 is sent to the optical switch SWI from 11→02→OR→O8−+SW2.
It is transmitted as I2→02→P0.

As described above, all the states described in FIGS. 5(a) to 5(d) can be realized by operations using conventional optical switches.

[Problem that the invention seeks to solve]

However, the optical network using the conventional optical switches described above has the following problems.

(a) Optical loss is greatest at discontinuities in optical paths, such as input points and output points of optical switches, or optical connectors, than in optical fibers or optical waveguides. Therefore, in the conventional configuration in which an optical signal always passes through two optical switches, optical loss increases.

(b) Since two optical switches are required for each node, the network becomes expensive if the price of the optical connector is also taken into account.

(1) There is no self-diagnosis method. In other words, when isolating a failure location, or when repairing a bypassed node is complete and connecting it to the network again to check its operation, an unused line (for example, line S when line P is in use) and Since another node (for example, a monitoring node) is required, the fault diagnosis work becomes complicated.

Problem (1) can be solved by inserting a third optical switch SW3 into the line S as shown in FIG. In Figure 7, optical switches SW1, SW2 and SW
By setting all 3 to exchange mode and sending out a self-diagnosis optical signal from the optical transmitter ○S while leaving the line P in the bypass state, SW2's I2 → 01 → SW3's ■2 → 0
．． →SW1's ■1→02→OR and the signal circulates, making self-diagnosis possible. However, this method is not practical because the problems (a) and (b) described above become even more serious.

The purpose of the present invention is to solve the above-mentioned problems.
An object of the present invention is to provide an optical switch having a structure in which not only normal state, standby ring switching, node bypass, and loopback means but also self-diagnosis means are combined on one substrate, and an optical network using the same.

[Means for solving problems]

The optical switch of the present invention is an optical switch including an optical waveguide formed by injecting a material having an optical refractive index increasing effect onto a dielectric substrate having an electro-photoelectric effect, wherein the optical waveguides are arranged substantially parallel to each other. The first waveguide is constructed of first, second, and third optical waveguides, and allows optical power to be exchanged by applying energy to a part of the first optical waveguide and the second optical waveguide from the outside. and a second waveguide approaching part and a third waveguide in a part of the second optical waveguide and the third optical waveguide, respectively, in front and behind the first waveguide approaching part with respect to the traveling direction of the light. The waveguide is characterized in that it is provided with an approach section and first, second, and third electrode pairs for applying energy from the outside to the first, second, and third waveguide approach sections.

The optical network of the present invention includes a plurality of nodes including the optical switch of the present invention, an optical transmitter, and an optical receiver connected in a ring shape by two optical fibers, one for normal use and one for emergency use. , two optical fibers from two adjacent nodes connected to the node and one optical fiber from the optical transmitter of the node are connected to the three input ends of the optical switch of one node. connected, and the three output terminals have two output terminals connected to the two adjacent nodes connected to the node.
It is characterized in that two optical fibers and one optical fiber to the optical receiver of the node are connected.

[Effect]

The optical switch of the present invention has three optical waveguides formed on the same dielectric substrate and three waveguide approach parts, in a 3×3 structure.
Configure a light switch. An optical network is constructed by connecting the input end and output end of this optical switch to two optical fibers and an optical receiver and an optical transmitter in the node, respectively.

Therefore, it is possible to configure an optical network using an optical switch that has normal state, protection ring switching, node bypass, loopback, and self-diagnosis means.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1(a) is a plan view showing an embodiment of the optical switch of the present invention, and FIG. 1(b) is an enlarged sectional view taken along the line xx'.

The optical switch of this embodiment is an optical switch including an optical waveguide formed by injecting a material having an optical refractive index increasing effect onto a dielectric substrate LN having an electro-photoelectric effect, wherein the optical waveguides are substantially parallel to each other. Consisting of second, second and third optical waveguides T1, T2 and T3 arranged in
A first waveguide approach part N1 that allows optical power to be exchanged by applying a voltage as energy to a part of the first optical waveguide T1 and the second optical waveguide T2 from the outside; A second waveguide approach part N2 and a third waveguide approach part N3 are provided in respective parts of the second optical waveguide T2 and the third optical waveguide T in front and behind the waveguide approach part N1, and the first and third waveguide approach parts First, second and third electrode pairs (El, E1'), (E2, E2') for externally applying energy to the second and third waveguide approach parts Nl5N2 and N3
) and (E3, E3') are provided.

Here, the substrate LN is a dielectric substrate having an electro-optic effect, such as LiNbO3. The electro-optical effect is the Pockels effect,
This is a phenomenon such as the Kerr effect in which the refractive index of light changes depending on an electric field. The optical waveguides T1, T2 and T3 are arranged on the substrate LN.
It is formed by injecting a material such as iO2 that makes the refractive index of light several percent higher than that of the substrate LN. I3, ■, and I5 are optical input ports, and 03.04 and 05 are optical output ports.

Waveguide adjacent parts N1, N2 and N3 are optical waveguides T1, T
The intervals are set such that the paths of the optical signals passing through T2 and T3 can be exchanged by applying an electric field.

When communicating with light with a wavelength of 1.3-, the optical waveguides T1 and T
The width of 2 and T3 is about 9 μm, and the waveguide adjacent part N, ,
The spacing between N2 and N is 2-lbcm. Electrode E1
, EI', E2, E2, E3 and E3' are the substrate LN
It is formed of Au or the like on the surface. φ is electrode E2.8
This is the electric field generated when a voltage is applied between 22. With proper dimensioning and voltage, this electric field φ gives
The light passing through the optical waveguide T1 transfers to the optical waveguide T2,
At the same time, the light passing through the waveguide T2 transfers to the waveguide T.

The feature of the present invention is that in FIGS. 1(a) and (b),
Three optical waveguides T1, T2 and T3 are provided on the substrate LN, and electrode pairs (E, ,E,') and (E2) are provided on the substrate LN, respectively.
, E2') and (E3, E3') are provided to form a 3×3 optical switch.

Next, the operation of the optical switch of this embodiment will be explained using explanatory diagrams shown in FIGS. 2(a) to 2(f).

Figures 2 (a) to (f) show the states in which the optical switch of this embodiment is used, with the white electrodes showing the electric field off (parallel mode), and the black electrodes showing the electric field on (exchange mode). represents.

FIG. 2(a) shows the normal state. The optical signal S, manually inputted from the optical input port I3, passes through the waveguide adjacent portion N1→N3 and is output from the optical output port 04.

The optical signal S2 inputted from the optical input port (2) passes through the waveguide adjacent portion N2→N3, and is output from the optical output port 05. The optical signal S3 manually generated from the predecessor capo)1=t passes through the waveguide proximal portion N2-+N and is output from the optical output port 03.

Thereafter, the transmission path of the optical signal can be found in the same manner.

FIG. 2(b) shows the spare ring switching state. in this case,
The optical signals S1, N2 and N3 are respectively ■3→N1→
N3→05, ■4→N2→N1→03, and ■5→N
It is transmitted along the route 2→N3→04.

FIG. 2(C) shows the bypass state. In this case, the optical signals S1, N2 and N3 are respectively ■3→N→N3→0
5, ■, →N2→, N3→04, and I5→N2→N
, →03.

FIG. 2(d) is another bypass state. In this case, the optical signals S1, N2 and N3 are respectively I3→N
, →03, I4→N2→N3→04, and I5→N
It is transmitted along the route 2→N3→05.

FIG. 2(e) shows the loopback state. In this case, the optical signals S1, N2 and N3 are respectively →N1→N
3→01, ■4→N2→N1→08, and l5-N2
→Transmitted via route N3-05.

FIG. 2(f) is another loopback state.

In this case, the optical signals 5ISS2 and N3 are each
3→N1→03, I4→N2→N3→06, and I
It is transmitted along the route 5→N2→NI-+04.

That is, the optical switch of this embodiment performs six types of operations depending on the transmission state of the optical signal.

In this embodiment, only the case where the optical path is switched by an electric field has been described, but the switching may also be performed using the effects of heat, magnetic field, etc.

FIG. 3 is a block diagram showing an embodiment of the optical network of the present invention.

In the optical network of this embodiment, four nodes A', B'C', and D' including the 3×3 optical switch SW of the present invention, an optical transmitter O8, and an optical receiver OR are used for normal use and for emergency use. Line P consisting of two optical fibers for
and S are connected in a ring shape, and the optical input ports, which are the three input ends of the optical switch SW of one node A', have two adjacent nodes B' and S connected to the node A'. Two optical fibers (lines P and S) from D' and one optical fiber from optical transmitter O8 of node A' are connected, and the three output ends, or optical output ports, are connected to node A'. two optical fibers (lines P and S) to two adjacent nodes B' and D' connected to node 8' and one to optical receiver OR of node 8'.
The main optical fiber is connected. Also, each node A',
B', C' and D' are each data control circuit MA
C, and P+, St and Ps are each node A
', B', C' and D' input and output.

The feature of the present invention is that in FIG. 3, each node A'B',
C′ and D′ are 3×3 type optical switches SW of the present invention.
It is to include.

Next, we will discuss the operation of the optical network of this example in the fourth section.
This will be explained with reference to explanatory diagrams shown in FIGS. (a) to (f).

FIGS. 4(a) to 4(f) show various operations when the 3X3 type optical switch SW of the embodiment of the present invention is incorporated into a node, and the respective states of FIGS. 2(a) to (f) It corresponds to In FIG. 4, in order to make the diagram easier to understand, the state of the optical switch SW is only shown by function using arrows.

FIG. 4(a) shows a normal signal transmission state. The optical signal input from the input part Ps of the primary is sent to the optical switch SW I3→04→OR→O8→■, →O as shown by the arrow.
3 and the output part P of the primary. is output from.

FIG. 4(b) shows the spare ring switching state. If there is an abnormality such as a fiber break on InP, optical switch S
W is switched as shown in the figure, and the optical signal is sent to the optical switch SW using the line S, I, →04→OR→○S−+I,
→Transmitted via route 03.

Figures 4(C) and 4) are in the bypass state. For example, if there is an abnormality in the optical transmitter O8, optical receiver OR1, or data control circuit MAC while line P is in use, these abnormal parts are bypassed (bypass state) by switching the optical switch SW. Similarly, in the case of the inside, the abnormal part is bypassed by switching the optical switch SW as shown in FIG. 4(d). This figure 4 (C
) and (d), the optical receiver OR
An optical path is formed between the optical transmitter O8 and the optical transmitter O8 in the order of ○S→■4→04→OR. Therefore, self-diagnosis is possible while in the bypass state. In addition, in the bypass state of FIG. 4(d), P,→■3→03→SO% and,
Since an optical path is formed that goes around each line P and S in the order of S1→■5→05→P, the cable can be easily diagnosed.

FIGS. 4(e) and 4(f) show the loopback state.

If input part S1 and output part P. When the two optical fibers on the side are disconnected, the optical switch SW switches as shown in Figure 4(e), and the optical signal input manually from the input section P+ is transferred to the optical switch SW ■3 → 04 → ○. R-, 03-
It is transmitted as I4→03→So. Or output section S. When the two optical fibers on the input section P1 side are disconnected, the optical switch SW switches as shown in FIG. 4(f), so that the optical signal input from the input section S is It is transmitted as follows: 5→04→OR→○S→■4→05→Po.

As described above, according to the present invention, by using only one optical switch of the present invention per node, all network states such as normal state, protection ring switching, node bypass, loopback, and self-diagnosis can be handled. can.

In addition, the three optical input ports of the optical switch SW ■3, I4
and I5 are connected with the human power section P+ and Sl and the transmitter O8, and the three optical output ports 03, ○4 and 05 are connected with the output section P0 and So and the receiver OR in any order. , all the switching described above can be realized.

〔Effect of the invention〕

As explained above, the present invention realizes, with a single optical switch, network configuration switching means that conventionally required two optical switches, such as normal state, protection ring switching, node bypass, and loopback. By configuring an optical network using , the following effects can be achieved.

(1) The number of optical switches and optical connectors can be reduced,
Light loss is reduced.

(2) Since the number of optical components such as optical switches and optical connectors can be reduced, the cost of the network can be reduced.

(3) Since self-diagnosis and cable diagnosis can be realized,
You can easily isolate the faulty part and check the operation when recovering from the fault.

In particular, the present invention can be highly effective when applied to optical networks in buildings where node renewals and wiring changes are frequent.

[Brief explanation of the drawing]

FIG. 1(a) is a plan view showing an embodiment of the optical switch of the present invention. Fig. 1 et al.) is an enlarged sectional view taken along the line xx'. FIGS. 2(a) to 2(f) are explanatory diagrams showing the operation. FIG. 3 is a block diagram showing an embodiment of the optical network of the present invention. FIGS. 4(a) to 4(f) are explanatory diagrams showing the operation. FIGS. 5(a) to 5(d) are explanatory diagrams showing various states of the ring type optical network. FIGS. 6(a) to 6(d) are explanatory diagrams showing the operation of an example of a conventional optical network. FIG. 7 is an explanatory diagram showing the operation of another example of a conventional optical network. A, A', BS B', CS C'...
Node, El, E,' , E2, E2' , E3, E3
'... Electrode, I1, I2, I3... Optical input port, LN... Board, MAC... Data control circuit, N
3, N2, N3...Waveguide vicinity, 00.02.03
...Optical output port, ○R... Optical receiver, O8...
Optical transmitter, P, S... line, Pr, S+-human power department,
Po5S. ,,,output section, S l %S2, S3...
Optical signal, SW, SWI, SW2, SW3... optical switch, Tl5T2, T3... optical waveguide, φ... electric field.

Claims (1)

[Claims] 1. An optical switch including an optical waveguide formed by injecting a material having an optical refractive index increasing effect onto a dielectric substrate having an electro-photoelectric effect, wherein the optical waveguides are substantially parallel to each other. It is composed of arranged first, second and third optical waveguides (T_1, T_2 and T_3), and exchanges optical power by applying energy to a part of the first optical waveguide and the second optical waveguide from the outside. a first waveguide approach portion (N_1) capable of a second waveguide approach section (N_2) and a third waveguide approach section (N_3); and first, second and third waveguide approach sections for externally applying energy to the first, second and third waveguide approach sections. An optical switch characterized by being provided with a third electrode pair. 2. A plurality of nodes including the optical switch of claim 1, an optical transmitter, and an optical receiver are connected in a ring shape by two optical fibers for normal use and for emergency use, and one of the nodes Two optical fibers from two adjacent nodes connected to the node and one optical fiber from the optical transmitter of the node are connected to the three input ends of the optical switch, and three outputs are connected to the three input ends of the optical switch. An optical network characterized in that two optical fibers to two adjacent nodes connected to the node and one optical fiber to an optical receiver of the node are connected to an end thereof.