FR2752119A1 - Cross-coupled optical fibre connector for communication network - Google Patents

Abstract

The connector has two subscriber waveguide networks, each having n inputs and n outputs. A demultiplexer nas k1 input ports and n output ports to which input wavelengths are allocated while preventing two input wavelengths of the same value appearing at the output. A multiplexer with n input ports and k2 output ports puts the signals in a predetermined order of wavelength. AN optical switch (34) selects certain of the n outputs and applies signals of a particular wavelength to certain input multiplexer ports for transfer to the output so as to be interconnected. k1 and k2 may be equal to each other and both are less than n.

Description

 The present invention relates to optical cross-connect equipment and signal addition / suppression equipment, and more particularly to cross-connect optical equipment and add / drop equipment for transmitting one or more optical signals having optical wavelengths desired from one or more optical fibers to one or more desired optical fibers in an optical network of a wavelength division multiplexed optical transmission system.

 Intensive studies have been conducted for years in the field of fiber optic communication networks using wavelength division multiplexing optical transmission technologies. An ordered array of waveguides is known as an element for multiplexing and demultiplexing optical signals having different wavelengths. For example, when an optical signal with multiplexed wavelengths and comprising n wavelengths A1 to λn separated by identical spacings, are sent to individual ports of an ordered network of waveguides having n ports At the input and n output ports as shown in Fig. 8, the demultiplexed wavelengths λ 1 to λ n are outputted by n output ports num 1 to num n. Signal wavelengths delivered from respective output ports # 1 to # n are shifted in the same sequence that corresponds to the input ports due to a periodicity of the ordered waveguide array.

For example, if a multiplexed wavelength optical signal, including the wavelengths λ 1 to λ n, enters at the input port # 1, a signal having a wavelength λ i is delivered through the port of output # 1, a signal having a wavelength λ 2 is output from the output port # 2, and a signal having the wavelength λ n is output from the output port # n. If the wavelength multiplexing optical signal comprising the wavelengths A1 to λn enters through the input port φ2, then a signal having a wavelength λ1 is output from the output port # n, a signal having wavelength λ2 is output from the output port φ1 and a signal having wavelength λ1 is output from the output port ((n1). In general, if an optical signal having a wavelength λ1 introduced at an input port φ is represented by λi (k), the optical signal is outputted by an output port φm, and we have
m = i-k + l when i-k + 1> 0
m = i-k + l + n when i-k + l <l.

 To ensure that a wavelength division multiplexing network system processes only optical signals except for its input and output portions, it requires cross-connect optical equipment which applies an optical signal from from any one of a plurality of input optical fibers to any one of a plurality of optical output fibers. Wavelength division multiplexing transmission systems are required to transmit the optical signals from any desired input optical fibers to any output optical fibers, even in terms of wavelengths. Conventional proposals have been made to divide a multiple wavelength division multiplexed optical signal into a wavelength and to apply individual wavelengths to other optical fibers via a switch optical (see for example GR Hill et al., "A Transport Network Layer Based on Optical Network Elements", IEEE-LT Vo. 11, Ne 5/6, 1993).

 FIG. 9, which is appended to the present application, is a block diagram of a conventional optical connection device of a four-wavelength multiplexing system, which transmits optical signals having a wavelength from three input optical fibers to one of three output optical fibers. The multiplexed optical signals with wavelength multiplexing, which each comprise wavelengths A1 to A4, propagate in three input optical fibers 10a, 10b and 10c and penetrate input ports 1 of ordered 4x4 waveguide arrays 12a, 12b, 12c. The ordered waveguide arrays 12a, 12b, 12c operate as elements for demultiplexing the multiplexed optical signal in a wavelength division multiplexing and containing wavelengths A1 to λ4, and output the lengths of the wavelength. individual wave A1 to A4 from four output ports # 1 to &num; 4.

 Optical signals having the wavelength A1, which are demultiplexed by the ordered arrays of waveguides 12a, 12b, 12c, are introduced into a 3x3 optical switch 14 and whose wavelength A2 is sent to a switch 3x3 optical 16, and whose wavelength A3 is sent to an optical switch 18 and whose wavelength A4 is sent to a 3x3 optical switch 20. Apparently, the equipment requires a number of optical switches 14, 16 , 18, 20 equal to the number of wavelengths to be multiplexed, so that the optical switch 14 transmits signals having for wavelength A1, that the optical switch 16 transmits the signals having for wavelength A2, that the optical switch 18 transmits signals having A3 wavelength and that the optical switch 20 transmits the signals having wavelength λ4.

 Three output signals from the optical switch 14 enter the input ports &num; 1 of ordered 4x4 waveguide arrays 22a, 22b, 22c. Three output signals from the optical switch 16 enter input ports &num; 2 of ordered 4x4 waveguide arrays 22a, 22b, 22c. Three outputs of the optical switch 18 enter input ports 3 of ordered 4x4 waveguide arrays 22a, 22b, 22c. Three output signals from the optical switch 20 enter input ports 4 of ordered arrays of 4x4 waveguides 22a, 22b, 22c.

The ordered waveguide gratings 22a, 22b, 22c act as optical elements for multiplexed optical signals multiplexed at wavelengths and containing the wavelengths λ1 to λ4 and originating from the optical switches 14, 16, 18, 20. Optical output signals from the ordered arrays of waveguides 22a, 22b, 22c are sent to output optical fibers 24a, 24b, 24c.

 In this configuration, by switching the connection between the inputs and outputs in the optical switches 14, 16, 18, 20, an optical signal having any desired wavelengths A1 to A4 from one of any of the input optical fibers 10a, 10b, 10c may be connected to one of the output optical fibers 24a, 24b, 24c. However, since the optical switches 14, 16, 18 do not connect two of the four inputs to a common output port, optical signals propagating in different input optical fibers 10a, 10b, 10c having a length common wave are not applied to a common output optical fiber 24a, 24b or 24c. If a time division multiplexing system is used, then the optical switches 14, 16, 18, 20 are controlled by timing in the time domain.

 Conventional equipment as shown in FIG. 9 requires ordered elements of waveguides 12a to 12c and 22a, 22c, which are provided in a number twice that of optical fibers to be interconnected, and require optical switches in a number corresponding to the wavelengths to be multiplexed according to optical wavelength multiplexing, each of the ordered waveguide arrays into input and output ports present in numbers equal to the number of fibers optics to be interconnected.

 Therefore, an object of the invention is to provide a cross-connect optical equipment providing the equivalent functions with a smaller number of optical elements.

 Another object of the invention is to provide a signal addition / suppression equipment capable of adding and deleting designated wavelengths, with a simple architecture.

 Optical cross-connection equipment according to the invention comprises first and second ordered waveguide networks comprising n inputs and n outputs, able to deliver signals having n wavelengths during predetermined wavelength intervals according to the invention. periodic cycles, and n optical switching means connected between the first and second ordered waveguide arrays and having m inputs and m outputs (with mxm <n), and in that it comprises multiple waveguides input optics which are respectively connected to m input ports in m intervals among n input ports of said first ordered array of waveguides, n output ports of said first ordered array of waveguides being connected to input ports of said optical switching means prepared for wavelengths so as to be optionally delivered by said n output ports, multiple optical waveguides the output ports being respectively connected to m predetermined output ports of said second ordered array of waveguides, and m output ports of each of said optical switching means being connected to input ports of said second ordered array of waveguides; wave, which outputs optical output signals having a waveform corresponding to said optical switching means from said m output ports of said second waveguide ordinate.

 By feeding some of the optical waveguides with optical signals to be added and eliminating optical signals to be removed from some of the output optical waveguides, a signal addition / suppression function can be realized.

 In this way, by using a small number of optical elements, any desired wavelength can be transmitted between multiple inputs and multiple outputs. Since this equipment can be made with a small number of optical elements, its scale can be miniaturized and its manufacturing cost can be reduced.

According to another aspect, the invention relates to an optical equipment for cross-connection of transfer of a desired wavelength applied to kl inputs at a desired output among k2 outputs, characterized in that it comprises
wavelength demultiplexing means having kl input ports and n output ports for assigning wavelengths contained in k optical inputs to n different output ports associated with said respective input ports while preventing the signals with a common wavelength and from different input ports are not delivered to a common output port;
wavelength division multiplexing means having n input ports and k2 output ports for multiplexing wavelength signals sent to said n input ports in a predetermined order of the wavelengths corresponding to said k2 ports of respective outputs and to output them from said k2 output ports; and
multiple optical switching means prepared for respective wavelengths to be crosslinked, said switching means selecting some of said n output ports of said wavelength dividing means, which can output signals having a plurality of wavelengths; particular wavelength and apply them to some of the input ports of said wavelength division multiplexing means, which send signals having said particular wavelength to outputs, so as to be interconnected.

Other features and advantages of the present invention will emerge from the following description given with reference to the accompanying drawings, in which:
- Figure 1 shows a block diagram showing a general arrangement of a first embodiment of the invention;
FIG. 2 is an explanatory diagram of wavelength multiplexing / division characteristics of ordered arrays of waveguides 32, 36 according to the embodiment;
FIG. 3 is a detailed diagram of the wiring of optical switches 34-1 to 34-16;
FIG. 4 is a block diagram of a general arrangement of optical switches 34-1 to 34-16 that behave like signal add / drop elements;
FIG. 5 is a diagram showing a connection of optical switches 40, 42 and 44;
FIG. 6 is a diagram showing another connection of optical switches 40, 42 and 44;
FIG. 7 is a diagram showing another connection of optical switches 40, 42 and 44;
FIG. 8 is an explanatory diagram of typical characteristics of multiplexing / wavelength division of an ordered waveguide network; and
- Figure 9 is a block diagram of a general arrangement of a conventional device.

 An embodiment of the invention will now be explained in detail with reference to the drawings.

 Fig. 1 is a block diagram of a general arrangement of an embodiment of the present invention. In this embodiment, 16 wavelengths are multiplexed according to optical wavelength multiplexing using four input optical fibers and four output optical fibers.

Reference numerals 30a, 30b, 30c and 30d refer to input optical fibers whose output optical signals are sent to input ports at a four wavelength spacing, namely # 1, &num; 9 and 13, the ordered array of 16x16 waveguides 32. The output ports # 1 and # 16 of the ordered array of waveguides 32 are bifurcated and connected to predetermined input ports. an optical switch device 34 comprising sixteen 4x4 optical switches 34-1 to 34-16. 64 (= 4x16) output ports of the optical switches 34-1 to 34-16 are connected to input ports of an ordered network of 16x16 waveguides 36 which acts as a multiplexing element for the lengths of 'wave. The ordered array of waveguides 36 uses only its output ports 1 to 4, to which output optical fibers 38a, 38b, 38c and 38d are connected.

 Figure 2 shows input / output characteristics of an ordered network of 16x16 waveguides used as an ordered array of waveguides 32 or 36.

 Figure 2 corresponds to a modification of Figure 8, with the use of n = 16. It is evident from this figure that the ordered array of waveguides has both a wavelength demultiplexing function and a wavelength division multiplexing function. Considering the wavelength A4 for example, when it enters the input port # 1, it goes out through the output port &num; 4. When it enters through the input port &num; 5, it exits through the output port &num; 16.

When it enters through the input port &num; 9, it exits through the output port &num; 12. When entering through input port # 13, it exits through the output port &num; 8.

 When wavelengths λ1 through λ16 are respectively sent to the input ports φ1 through φ16, their wavelength division multiplexed signal is output from the output port φ1. When A2 to A16 and A11 are respectively sent to ports # 1 through # 16, their wavelength multiplexed signal is output from the output port &num; 2. When wavelengths A3 to A16, λ1 and λ2 are respectively sent to the input ports φ1 through φ16, their wavelength division multiplexed signal is output from the output port &num; . When A4 and A16 and A1 to A3 are respectively sent to the input ports &num; 1 to &num; 16, their wavelength division multiplexed signal is output from the output port &num; 4.

 In the ordered array of waveguides 36, output ports &num; 5 through &num; 16 are not used. Therefore, when optical signals having wavelengths other than A1 and A4 are sent to the input port 1, for example of the ordered array of waveguides 36, no output signal is output from the signals. output ports &num; 1 to # 4. This means rejection of optical input signals with unwanted wavelengths.

 Optical switches 34-1 to 34-16 are switching elements each for transmitting the optical signals input at four input ports to four output ports, respectively, under control of an external control signal. They are prepared for waveguides A1 to A16. More specifically, the optical switch 34-1 is prepared for the wavelength λ1, the optical switch 34-2 for the wavelength λ2, etc., and the optical switch 34-16 is prepared for the length of the wavelength. wave A16.

 Fig. 3 shows a connection arrangement of optical switches 34-1 & 34-16 and input ports of the ordered array of waveguides 36. The connection arrangement is illustrated only for optical switches 34-1, 34-5, 34-9 and 34-13 for simplification. Wavelengths to be delivered are indicated on the output ports of the ordered array of waveguides 32, and wavelengths to be input are indicated at input ports of the ordered array of guides 36. wave. Optical output fibers 38a to 38d can be selected by appropriate selection of one of four input ports of the ordered waveguide array 36 assigned to an identical wavelength for the input of the optical signal. .

 Four optical switch input ports 34-1 are connected to output ports &num; 1, &num; 5, &num; 9 and &num; 13 of the ordered array of waveguides 32, which deliver the wavelength a1. Four optical switch output ports 34-1 are connected to input ports # 1, # 16, # 15 and # 14 of the ordered array of waveguides 36, which are prepared for inputs of FIG. wavelength λ1. In general, four input ports of an optical switch 34-1 are connected to four output ports &num; i, &num; (i + 4), &num; (i + 8) and &num; (i + 12) (16 being subtracted if the port number is greater than 16) of the ordered array of waveguides 32, which are prepared for the wavelength λ1, and four output terminals of the optical switches 34-i are connected to the ports i, # (i-1), &num; (i-2) and &num; (i-3) (16 being added if the port number is less than 0) of the ordered array of waves 36, which are prepared for the wavelength λ 1.

 It is also evident in Fig. 3 that each output port of the ordered array of waveguides 32 is subdivided into four and is connected to predetermined switches in optical switches 34-1 to 34-16. Outputs from all four outputs of certain predetermined switches among optical switches 34-1 to 34-16 are connected to input ports of the ordered array of waveguides 36.

 As explained above, the ordered array of waveguides 36 does not deliver, from the output ports 1 to 4, optical signals having wavelengths other than those assigned to the ports of the present invention. 'Entrance. That is why, although an optical signal of wavelength A1 delivered by the input port # 1, another optical signal of wavelength λ 5 delivered by the input port &num; 5, another wavelength optical signal Ag from the input port &num; 9 and another wavelength input signal A13 from the input port &num; 13 may exist at the output port &num; 1 of the ordered array of waveguides 32, only the optical signal having the wavelength λ1 and present on the output port φ1 of the ordered array of waveguides 32 is substantially operative as an input signal applied to the input port &num; 1 of the ordered array of waveguides 36, even when the optical switch 34-1 connects the output port &num; 1 of the ordered array of waveguides 32 to the input port & num 1 of the ordered network of waveguides 36.

 Considering the wavelength Δ5 by way of example, it will be explained below how such optical signals are applied to the optical input fibers 30a to 30d to the output optical fibers 38a to 38d.

The optical signals having the wavelength λ 5 and moving in the input optical fibers 30a, 30b, 30c and 30d are respectively sent to input ports num 1, num 5, num 9 and num; 13 of the ordered array of waveguides 32 and are output from the output port &num; 5, &num; 1, &num; 13 and &num; 9. The output signal output from output ports # 1, # 5, # 9, and # 13 of the ordered array of waveguides are wavelengths A1, A5, Ag, and λ13. Therefore the output ports &num; 1, &num; 5, &num; 9 & &num; 13 are connected to the optical switches 34-1, 34-5, 34-9 and 34-13.

 Four output ports of the optical switch 34-5 are respectively connected to input ports # 2, # 3, &num; 4 and # 5 of the ordered array of waveguides 36. Four output ports of the switch 34-9 are respectively connected to the input ports &num; 6, &num; 7, &num; 8 and &num; 9 of the ordered array of waveguides 36. Four output ports of the optical switch 34-13 are connected to input ports # 10, # 11, # 12 and # 13 of the ordered waveguide array 36. Four output ports of the optical switch 34-1 are connected to the input ports &num; 1, & num 16, 15 and 14 of the ordered array of waveguides 36. However, since the wavelength λ 5 is not assigned to the input ports num 6 to 16 and num; 1 are connected to the output ports of the optical switches 34-9, 34-13 and 34-1, these ports are not valid as inputs for the ordered array of waveguides 36 regardless of the state of c. Optical switches 34-9, 34-13 and 34-1 are provided, and input signals from the single optical connector 34-5 are effective for the ordered array of waveguides 36.

Optical signals having wavelengths
A1, Ag and A13 in addition to the wavelength A5 penetrate at four input ports of the optical switch 345. However, since these four output ports of the optical switch 34-5 are connected to the ports of input 2, &num; 3, &num; 4 &num; 5 of the ordered array of waveguides 36, at which the wavelengths λ1, λg, and λ13 are unaffected, the optical signals having the lengths of A1, Ag and A3 are rejected by the ordered array of waveguides 36 in any connection state of the optical switch 34-5.

 Therefore, it is sufficient to consider the wavelength λ only in the optical switch 34-5. Four optical switch 34-5 input ports are respectively associated with input optical fibers 30a, 30b, 30c and 30d. When the optical switch 34-5 connects the first input port to the first output port, an optical signal having the wavelength λ 5 delivered by the input optical fiber 30a is sent to the input port &num; an ordered array of waveguides 36, and is output from the output port # 1 of the ordered array of waveguides 36 to the output optical fiber 38a. When the optical switch 34-5 connects the first output port to the second output port, a wavelength optical signal A5 from the input optical fiber 30a is sent to the input port 4 of the ordered network. 36 and is output from the output port 2 of the ordered waveguide array 36 to the output optical fiber 38b. In the same way, the optical signal of wavelength λ 5 delivered by the input optical fiber 30a can be sent to the optical fiber 38c or 38d. That is, four output ports of the optical switch 34-5 are respectively associated with output optical fibers 38a and 38d. The same is also true for optical signals of wavelength A5 delivered by the input optical fibers 30b, 30c and 30d.

 As previously explained, the embodiment shown above enables an optical signal having any desired wavelength to be transmitted from four input optical fibers 30a to 30d to any desired fiber among the four fibers. output optics 38a to 38d. In addition, each wavelength can select any desired combination of an input optical fiber and an output optical fiber to be connected.

 Optical switches 34-1 to 34-16 are optical elements that can not connect multiple input ports to a single output port, but can connect any one of the four input ports to any one of the four input ports. four output ports.

 The embodiment shown in FIG. 1 can act as a signal addition / suppression function for desired wavelengths through the use of special optical switches having a more limiting switching function as optical switches. 34-1 to 34-16. FIG. 4 represents a block diagram of a general arrangement of optical switches 34-1 to 34-16 that can be used for this purpose.

 In FIG. 4, the reference numerals 40, 42, 44 designate 2x2 optical switches, which can be externally controlled by connection and cross connection. Among four input ports a, b, c and d in one of the optical switches 34-1 to 34-16, the input ports a and b are respectively connected to two input ports of the optical switch 40, and the input ports c and d are respectively connected to two input ports of the optical switch 42. One of the output ports of the optical switch 40 is connected to one of the input ports of the optical switch 44, and the other input port of the optical switch 40 is connected to the output port c of the optical switches 34-1 to 34-16. One of the output ports of the optical switch 42 is connected to the other input port of the optical switch 44, and the other output port of the optical switch 42 is connected to the output port d of optical switches 34-1. at 34-16. One of the output ports of the optical switch 44 is connected to the output port a of optical switches 34-1 to 34-16, and the other output port of the optical switch 44 is connected to the output port b of the optical switches. 34-1 to 34-16.

 Therefore, the input optical fibers 30b and 30d are used for optical signals to be added, and the output optical fibers 38c and 38d are used for the optical signal to be removed.

That is, the optical signals having desired wavelengths, which must be added, are introduced into the input optical fibers 30b and 30d, and optical signals of suppressed wavelengths are removed from the optical fiber output 38c and 38d.

 As previously explained, the input ports a, b, c and d of the optical switches 34-1 to 34-16 respectively correspond, the optical input signals sent to the input ports a, b, c and d are respectively output from the output ports a, c, d and b as shown in FIG. 6. That is, the optical input signal sent to the input port d is added to the output port b, and the optical input signal sent to the input port c is removed from the output port d.

 When the optical switches 40 and 44 are positioned to establish a cross connection, while the optical switch 42 is set for a direct connection, the input optical signals sent to the input ports a, b, c and d are respectively delivered by the output ports c, b, a and d. That is, the input optical signal sent to the input port b is added to the output port b, the input optical signal sent to the input port a is removed from the output port c, and the input optical signal sent to the input port c is added to the output port a.

 By controlling in this manner, from the outside, the 2x2 optical switches 40, 42 and 44, all the desired wavelengths in the input optical fibers 30a and 30c can be suppressed and all the lengths can be added. desired waves in the output optical fibers 38a and 38b.

 As previously described, according to the invention, the optical signals having any desired wavelengths can be transmitted by cross-connection between multiple input optical fibers and multiple output optical fibers through use. a small number of optical elements. In addition, since the equipment requires only a small number of optical elements, its size and cost can be reduced. Furthermore, the invention can be applied to a wavelength division multiplexed optical signal, which comprises a large number of wavelengths, and can contribute to the production of D-division multiplexing transmission systems. wave, which use many wavelengths.

Claims (8)

 1. Optical cross-connection equipment, characterized in that it comprises first and second ordered arrays (32,36) of waveguides having n inputs and n outputs, able to deliver signals having n wavelengths during predetermined intervals of wavelengths according to periodic cycles, and n optical switching means (34-1 - 34-16) connected between the first and second ordered waveguide arrays and   <A having m inputs and m outputs (with m x ss <n), and in that it includes  multiple input optical waveguides (30a-30d) which are respectively connected to m input ports in m intervals of n input ports of said first ordered array of waveguides;  n output ports (&num; 1 &num; 16) of said first ordered array of waveguides being connected to input ports of said optical switching means prepared for wavelengths so as to be optionally delivered by said n output ports;  multiple output optical waveguides (38a-38d) being respectively connected to m predetermined output ports of said second ordered array of waveguides; and  m output ports (1- &num; 16) of each of said optical switching means being connected to input ports of said second ordered array of waveguides, which outputs optical output signals having a shape of wave corresponding to said optical switching means from said m output ports of said second waveguide ordinate.  2. Add / remove equipment comprising said connection device according to claim 1, characterized in that optical signals to be added are introduced into some of said input optical waveguides (30a-30d), and optical signals to be removed are removed from some of said optical output waveguides (38a-38d).  3. Optical equipment for cross-connect transfer of a desired wavelength applied to kl  e inputs to a desired output among k2 outputs, characterized in that it comprises  wavelength demultiplexing means having kl input ports and n output ports for assigning wavelengths contained in k optical inputs to n different output ports associated with said respective input ports while preventing the signals with a common wavelength and from different input ports are not delivered to a common output port;  wavelength division multiplexing means having n input ports and k2 output ports for multiplexing wavelength signals sent to said n input ports in a predetermined order of the wavelengths corresponding to said k2 ports of respective outputs and to output them from said k2 output ports; and  multiple optical switching means (34-1 - 34-16) prepared for respective wavelengths to be crosslinked, said switching means selecting some of said n output ports of said length division means; which can output signals having a particular wavelength and apply them to some of the input ports of said wavelength division multiplexing means, which send signals having said particular wavelength to outputs, to be interconnected.  4. Optical cross-connection equipment according to claim 3, characterized in that kl = k2.  5. Cross-connection optical equipment according to one of claims 3 or 4, characterized in that said means for dividing wavelengths comprise an ordered array of waveguides.  6. The optical cross-connect equipment according to one of claims 3 or 4, wherein kl <n and said wavelength division means use kl entries among n inputs of an ordered network of waveguides having n inputs and n outputs.  Optical cross-connect equipment according to any one of claims 3 to 6, characterized in that said wavelength division multiplexing means comprise an ordered array of waveguides.  8. The optical cross-connect equipment according to one of claims 3 to 7, wherein k2 <n, and said wavelength multiplexing means use k2 outputs out of n outputs of an ordered network of waveguides. waves having n inputs and n outputs.