JP3334738B2 - Optical frequency routing type time division highway switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time division highway switch for switching an optical signal on a plurality of time division input highways to an arbitrary output highway for each time slot, and more particularly to a self-routing in an ATM switch using an optical frequency. The present invention relates to an optical frequency routing type time division highway switch which is a switch.

[0002]

2. Description of the Related Art FIG. 1 shows an example of the configuration of a conventionally proposed N × N optical frequency routing type time division highway switch.
FIG. In FIG. 17, 15-1-1 to 15-1-
N is an input highway, 15-2-1 to 15-2-N are frequency converters, 15-3 is an N × N frequency router, 15-4
-1 to 15-4-N are frequency multiplexed output buffers;
−5-1 to 15-5-N are output highways.

In this configuration, a time-divided input optical signal is converted by a frequency converter 15-2 for each time slot.
The signal is converted to a predetermined frequency channel corresponding to the target output highway. These optical signals are all transmitted to the frequency router 15.
By -3, routing is performed to a predetermined output port according to the input port and the frequency channel. Thereafter, the optical signals on a plurality of different frequency channels existing in the same time slot are output to the output highway by the frequency multiplexing output buffer 15-4 such that only one signal exists in one time slot. As described above, the switching operation is performed by allocating the frequency channels by the frequency converter. This switch configuration is described in K. Sasayama et a
l, "Photonic ATM switch using FRONTIERNET", Electron
ics Letters, 1993, 20, pp. 1778-1779.

[0004]

The above configuration has the following problems.

(1) Since the frequency conversion width required for the frequency converter is N channels, the number of input / output highways N
Is required, a wide frequency conversion width is required for one frequency converter.

(2) Since the number of frequency channels used in the frequency router is N, when increasing the number N of input / output highways, a large number of frequency channels must be set.

(3) Since signals of up to N channels may arrive at the frequency multiplex type output buffer at the same time after being frequency-multiplexed, when the number N of input / output highways is increased, the device constituting the buffer must be Wide operating width is required. In particular, when an optical amplifier that amplifies frequency-multiplexed optical signals in a buffer is used in a buffer, a signal with a high degree of multiplexing increases the input light intensity to the amplifier, causing disadvantageous operations such as a decrease in the degree of amplification and a non-linear phenomenon. There is.

[0008] The present invention has been made in view of the above,
It is an object of the present invention to provide an optical frequency routing type time-division highway switch which requires a small number of conversion widths of a frequency converter, the number of frequency channels, and the number of input channels to a frequency multiplexing type output buffer, and a narrow band. It is in.

[0009]

To achieve the above object, according to the present invention, there is provided a time division highway for exchanging optical signals on a plurality of time division input highways with an arbitrary output highway for each time slot. A switch connected to each of the input highways, and a maximum of r frequency-multiplexed optical signals input from each input highway and fed back from an output module connected to the output highway of the same number. An input buffer for synchronizing and outputting a maximum of r optical signals with respect to the optical signal, r frequency converters for assigning a frequency channel for each time slot to the output optical signal from the input buffer, and An input module provided with a combiner for combining the output optical signals of the input module and an output optical signal from the input module for each time slot. A frequency router connected to a specific output highway according to a frequency channel, and an optical signal connected to each output port of the frequency router and corresponding to a destination address for each time slot with respect to an output optical signal from the frequency router. An output signal selection circuit for selecting only the output signal and outputting the other optical signal to another output line, and the same time slot for the optical signal selected from the output signal selection circuit. An output module comprising a frequency multiplexing type output buffer for outputting optical signals on a plurality of different frequency channels existing in a time slot so that only one signal is present;
The gist is to have r feedback signal lines for returning an unselected optical signal from the output module to the input module of the same number.

The present invention described in claim 2 is the same as the claim 1.
In the invention described above, the frequency router includes a plurality of input optical waveguides for inputting an optical signal, a first slab-shaped optical waveguide for receiving an optical signal from the input waveguide, and the first slab-shaped optical waveguide. And a second slab-shaped light guide for receiving an optical signal from the array waveguide and receiving the optical signal from the array waveguide. The gist is an arrayed waveguide grating filter having a waveguide and a plurality of output optical waveguides for receiving and outputting an optical signal from the second slab-shaped optical waveguide.

Further, the present invention according to claim 3 provides the invention according to claim 1.
In the described invention, the frequency router has N inputs and N inputs.
Has an output,

Each optical signal having a frequency channel number of (N−p + q) mod N (where N, p, and q are integers and 0 ≦ p, q ≦ N−1) is transmitted from the input port p to the output port q. The point is to connect.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the frequency router has N inputs and N outputs (where N = ar ^a and a and r are arbitrary positive integers). Have

(N− (ir ^a + j) + (((i + 1) mod a) r ^a + (j mod ra ^-1 ) r + m)) mod N (i, j, m are integers and 0 ≦ i ≦ a-1, 0 ≦ j ≦
(output port from the ^{ir a + j) ((i} + 1) input ports each optical signal having a ^{r a -1,0 ≦ m ≦ r-} 1) becomes the frequency channel number ^{mod a) r a + (jmod} r a-1) r +
The gist is that the connection is made to r consecutive m).

According to a fifth aspect of the present invention, there is provided a time-division highway switch for exchanging optical signals on N time-division input highways with an arbitrary output highway for each time slot. N input modules for processing an optical signal and a return optical signal from an output module connected to an output highway of the same number, and an N-input N-output frequency router connected to the input module (provided that N = ar ^a , and a and r are arbitrary positive integers) and some output ports s of the frequency router
(R ^a -1) extension output terminals connected to (0 ≦ s ≦ r ^a -1), (r ^a -1) extension input terminals,
The output highway and the output terminal for expansion or the remaining output port t (r ^a ≦ t
≤N-1) M output optical frequency-routing type time-division highway switch modules having N output modules connected to each other, and an extension output of the first optical frequency routing type time-division highway switch module. The terminals are respectively connected to those having the same number as the expansion input terminals of the second optical frequency routing type time division highway switch module, and the expansion output terminals of the second optical frequency routing type time division highway switch module are , The third input terminal of the optical frequency routing type time division highway switch module is connected to the same input terminal of the same number, and finally the output terminal for extension of the M-th optical frequency routing type time division highway switch module. Is the first optical frequency routing type time division highway switch module. The division highway switch modules at M optical frequency routing type by connecting each of the same number of extension input terminals of Le and gist to connect to annular.

Further, the present invention according to claim 6 provides the present invention according to claim 5.
In the described invention, the optical frequency routing type time division highway switch module is newly inserted between the M-th optical frequency routing type time division highway switch module and the first optical frequency routing type time division highway switch module. The gist of this is to expand the switch scale.

[0015]

According to the first aspect of the present invention, the optical signal on the input highway is input to the input buffer of the input module, and up to r frequency-multiplexed optical signals from the output module are input to the input buffer. Then, a maximum of r optical signals are output synchronously, and the output optical signals from the input buffer are assigned frequency channels for each time slot by the frequency converter, merged by the merger, and input to the frequency router. . The frequency router outputs to a specific output highway according to the frequency channel for each time slot,
It is input to the output signal selection circuit of the output module. The output signal selection circuit selects and outputs only the optical signal corresponding to the destination address for each time slot with respect to the optical signal output from the frequency router, and outputs the other optical signals to another output line. The frequency multiplexing type output buffer outputs an optical signal on a plurality of different frequency channels existing in the same time slot to the selected optical signal such that only one signal exists in one time slot.

Further, in the present invention according to claim 2,
The frequency router is composed of an arrayed waveguide grating filter. In the arrayed waveguide grating filter, an optical signal is input to a plurality of input optical waveguides, and an optical signal from the input waveguide is transmitted to a first slab optical waveguide. Receiving an optical signal from the first slab-shaped optical waveguide with an arrayed waveguide diffraction grating; receiving an optical signal from the arrayed waveguide diffraction grating with a second slab-shaped optical waveguide; An optical signal from the second slab optical waveguide is received by a plurality of output optical waveguides and output.

Further, according to the third aspect of the present invention,
The frequency router has N inputs and N outputs, and (N-p + q)
Each optical signal having a frequency channel number of mod N is connected from the input port p to the output port q.

According to the present invention, the frequency router has N inputs and N outputs, and (N− (ir ^a + j)).
+ (((I + 1) mod a) r ^a + (jmod ra ^-1 ) r +
m)) Each optical signal having a frequency channel number of mod N is transmitted from the input port (ir ^a + j) to the output port ((i +
^{1) mod a) r a +} (jmod r a-1) is connected to the r successive of r + m).

Further, according to the present invention described in claim 5,
An expansion output terminal of the first optical frequency routing type time division highway switch module is connected to an extension input terminal of the second optical frequency routing type time division highway switch module having the same number, and a second optical frequency routing is performed. The extension output terminal of the time division highway switch module is connected to the same number of the extension input terminal of the third optical frequency routing type time division highway switch module, and finally the Mth optical frequency routing type time division is connected. The output terminal for expansion of the highway switch module is the first
M optical frequency routing type time division highway switch modules are connected in a ring by connecting to the same number of expansion input terminals of the optical frequency routing type time division highway switch module.

Further, according to the present invention as set forth in claim 6,
The switch scale is expanded by newly inserting the optical frequency routing type time division highway switch module between the M-th optical frequency routing type time division highway switch module and the first optical frequency routing type time division highway switch module. ing.

[0021]

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

FIG. 1 is a block diagram showing a configuration of an optical frequency routing type time division highway switch according to one embodiment of the present invention. In FIG. 1, 1-1-1 to 1-1-
N is an input highway, 1-2-1 to 1-2-N is an input module, 1-3 is an N × N frequency router, and 1-4-1 to 1-4-1
1-4-N is an output module, 1-5-1 to 1-5-N
Is an output highway, and 1-6-1 to 1-6-N are feedback signal lines.

FIG. 2 shows the input module 1-2 shown in FIG.
FIG. 3 is a block diagram showing the configuration of FIG. In FIG. 2, 5-1
Is an input highway, 5-2 is an input buffer, 5-3-1
５−5-3-r is a frequency converter, 5-4 is a merger, 5-5
Is a feedback signal line.

FIG. 3 shows the output modules 1-4 shown in FIG.
FIG. 3 is a block diagram showing the configuration of FIG. In FIG. 3, 6-1
Is an output signal selection circuit, 6-2 is a frequency multiplex type output buffer, 6-3 is an output highway, and 6-4 is a feedback signal line.

At the same time as the optical signal on the input highway 1-1 is input to the input buffer 5-2, the feedback signal line 1-6
The maximum r multiplexed optical signals are input from the output module 1-4 to the input buffer 5-2 through the interface. Input buffer 5-
2 outputs a maximum of r signals from the maximum of r + 1 simultaneously arriving optical signals to the output terminal on a first-come, first-served basis. Signals that cannot be output due to contention upon arrival will be stored in the buffer.

The signal from the input buffer is converted by the frequency converter 5-3 into a frequency channel corresponding to the destination address for each time slot. A specific routing algorithm will be described later. The frequency-converted signal is
The signals are merged by the merger 5-4 and sent to the frequency router.

The frequency router 1-3 includes an input module 1
-2 is output to a predetermined output port according to the input port position and the frequency channel, and sent to the output module 1-4.

The output signal selection circuit 6-1 in the output module 1-4 outputs the frequency multiplexed output buffer 6 to the input signal when the address corresponds to the output highway.
To the input module 1-2 via the feedback signal line 6-4 if they do not match. The frequency multiplexing type output buffer 6-2 outputs 1 to the frequency multiplexed input signal.
The signal is output to the output highway 6-3 so that only one signal exists in the time slot.

FIG. 4 is a waveguide layout diagram of an arrayed waveguide diffraction grating filter constituting the frequency router 1-3 (see Japanese Patent Application Laid-Open No. 2-244105). In FIG.
2-1-1 to 2-1-N are input optical waveguides, 2-2 and 2-
3 is a slab-shaped optical waveguide, 2-4 is an arrayed waveguide diffraction grating, and 2-5-1 to 2-5-N are output optical waveguides. The frequency multiplexed optical signal from each input optical waveguide 2-1 is diffracted by the slab optical waveguide 2-2, and the arrayed waveguide diffraction grating 2
Enter -4.

Here, the optical signals from the plurality of input optical waveguides in the slab optical waveguide enter the arrayed waveguide diffraction grating 2-4 independently of each other due to the incoherence of light. The array waveguide is composed of a sufficient number of channel waveguides to receive all of the input light spread by diffraction. This array waveguide is composed of a plurality of optical waveguides having different lengths from each other, and has a function equivalent to a diffraction grating. That is, optical signals having different frequencies are deflected in a direction corresponding to the frequency after propagating in the array waveguide. Thereafter, the light is independently focused on the output optical waveguide 2-5 for each signal by the output side slab optical waveguide 2-3. As described above, the light condensing position differs depending on the frequency due to the angular dispersion of the arrayed waveguide diffraction grating. In this way, a filter having different input / output optical waveguide connections for each frequency can be configured. This filter is also lossless in principle.

FIG. 5 shows a frequency channel assignment table of the frequency router to show the frequency channels that determine the input / output port connection of the frequency router 1-3. In general, the frequency channel number connecting the input port p and the output port q is represented by a radix N remainder system, that is, (N-p + q) mod N. The arrayed waveguide grating filter shown in FIG. 4 is an optical passive circuit, and the assignment of the frequency channels shown in FIG. 5 is determined by its reciprocity and the numbering of input / output ports. In FIG. 5, a dashed line indicates a discontinuity point of the frequency channel.

FIG. 6 shows how to use a frequency channel in the N × N frequency router 1-3. Here is a N = ar ^a, the input port number

Equation 5] ^{ir a + j (i = 0~a} -1, j = 0~r a -1) output port connected to the port indicated by the

６ (i + 1) mod a｝ r ^a + ｛j mod ra ^-1 ｝ r + m (m = 0 to r−1) (only hatched portions in the figure) . Therefore, the frequency channel number used is

Equation 7 is a the r {(i + 1) mod a } r a + {jmod r a-1} r + m (m = 0~r-1). In FIG. 6, some of the frequency channel numbers are omitted. Also,
The dashed line indicates the discontinuity of the frequency channel. Since these frequency channel numbers do not cross portions where frequency channels become discontinuous in the router as shown in the figure, continuous r channels are guaranteed. The use shown here has the following advantages.

(1) The frequency converter only needs to have at most a continuous r channel width as the conversion width, and does not require a wide band as in the prior art.

[0034] (2) the frequency channel used in the frequency ^{router, r a-1 ~2r a -r} a-1 consecutive 2
Since (r-1) r ^a-1 +1 (seed) channels,
The operating band of various optical components (optical amplifiers and the like) used in the switch does not require a wide band as in the related art.

(3) Since the optical signal arriving at the output port is at most r channels, the device constituting the frequency multiplexing type output buffer does not require the wide band property and the wide dynamic property as in the related art.

The wide dynamic property means that the operation can be performed when the input light intensity fluctuates dynamically because the number of multiplexes at the time of buffer arrival varies from 0 to the maximum value for each time slot. In addition, when an optical amplifier is used to amplify frequency multiplexed optical signals in a buffer in a buffer, a signal having a high degree of multiplexing increases the input light intensity to the amplifier, and causes disadvantageous operations such as a decrease in the degree of amplification and a non-linear phenomenon. However, when the multiplicity is low, such a problem can be avoided.

FIG. 7 shows that a = 3, r = 2, N in FIG.
== 24 shows a specific example. The conversion width of the frequency converter is 2 channels at any input port, the number of channels used is 9 from 4 to 12, and only a maximum of 2 channels arrive at any output port.

FIG. 8 shows an example in which multi-hop routing is actually performed in the specific example of FIG. To route from input port 0 to output port 7, first go from input 0 to output 9 on frequency channel 9, return to input 9 through the feedback signal line, pass through output 19 on frequency channel 10, and finally At 12 the output 7 is reached.

Here, the routing algorithm of the multi-hop switch network will be described. I / O port address

Equation 8] [i, j] ≡ [i , j a-1 j a-2 j a-3 ··· j 0] (i = 0~a-1, j = 0~r a -1, j _p = 0 to a-
1, p = 0 to a-1) That is,

(Equation 9) Is displayed. Select any input and output ports, the input address [i ^s, j ^s], put a [i ^d, j ^d] an output address. Also, let H be the distance of i between input and output. Ie

(Equation 10) And The first hop is from [i ^s , j ^s ]

Equation 11] is routed to the ^{[(i s +1) mod a} , j s a-2 j s a-3 j s a-4 ··· j s 0 j d H-1]. That is, (i) i is increased by 1 (however, the remainder system of the radix a).

(Ii) j is MSD (Mors Significant Dig)
) to remove the (in this case, j ^s _{a- 1),} the entire digit
Is shifted to the left by 1 and the LSD (Least Significant Di
git) and add a digit (here, j ^d _H-1 ) corresponding to the output address.

The following operation is performed. After hopping H times in this way,

(Equation 12) To reach the address. This equal to the output address of the target [i ^d, j ^d], is output to the output highway (frequency multiplexing type output buffer). Otherwise, by the rear a times (collectively H + a time) similarly hops can always reach the output address of _{^{[i d, j d a-}} 1 j d a-2 ··· j d 0]. The above is a brief description of the routing algorithm. If the specific example shown in FIG. 8 is described again by the above description method, 0 [0000] → 9 [1,001] → 19 [2,01
1] → 7 [0,111].

FIG. 9 shows an example of the configuration of the input buffer 5-2 which is a component of the input module 1-2. 9, 7-1 is an input highway, 7-2 is a feedback signal line,
7-3 is a multiplexer, 7-4-1 to 7-4-L are loop-type optical delay line buffer units, and 7-5-1 to 7-5-L are 2
× 2 optical switches, 7-5-1-1 to 7-5-L-4 are optical gate switches, 7-6-1 to 7-6-r are frequency selectable 1 × 2 switches, and 7-7 is a monitor 7-8, a buffer control circuit, 7-9, a control signal line of a 2 × 2 optical switch, and 7-10, a control signal line of a frequency selective 1 × 2 switch.

Input highway 7-1 and feedback signal line 7-2
Are input by the multiplexer 7-3 to a buffer array in which a plurality of loop-type optical delay line buffer units 7-4 and a plurality of 2 × 2 optical switches 7-5 are cascaded. Is entered. Here, one loop type optical delay line buffer unit 7-4 can collectively buffer the frequency multiplexed signal as a buffer for one time slot. The input signal goes straight by turning on the optical gate switch 4 (7-5-1-4) in the 2 × 2 optical switch 7-5 until immediately before the occupied buffer unit. When the stored buffer unit is reached, the optical gate switch 2
(7-5-1-2) is turned on and input to the buffer unit. During buffering, the optical gate switch 1 (7-5-1-1) is turned on to orbit the buffer unit.

When the next unit becomes empty, the optical gate switch 3 (7-5-1-3) is turned on to send a signal to the next stage. The signal from the buffer unit 7-4 at the last stage is output to the output port only from the frequency multiplexed signal by the frequency selection type 1 × 2 switch 7-6. To the frequency selective type 1 × 2 switch 7-6.

All of these controls are performed based on the buffer input signal monitored by the branching unit 7-7. The buffer control circuit 7-8 analyzes the time slot / frequency channel occupation state of the buffer input signal, and controls the operation of each switch through the control signal lines 7-9 and 7-10 so as to avoid contention. As described above, for signals arriving from the input highway and the feedback signal line at the same time, only signals having mutually different output addresses are output in synchronization by the input buffer.

FIG. 10 shows a frequency selection type 1 × 2 switch 7
-6 shows a configuration example. In FIG. 10, 8-1 is a ring-shaped optical resonator, 8-2 is a phase shifter, 8-3 to 8-4 are directional couplers, and 8-5 is a signal from a frequency-selection type 1 × 2 switch at the preceding stage. Input port, 8-6 is the next stage frequency selectable 1 × 2
Output port to switch, 8-7 is frequency converter 5-3
And 8-8 are control signal lines of the frequency selection type 1 × 2 switch.

Of the frequency multiplexed signal input from the input port 8-5, only the channel that matches the resonance frequency determined by the optical path length of the ring-shaped optical resonator 8-1 is the output port 8-.
7 and the other frequency channels are output from output ports 8-6. The resonance frequency is controlled by the control signal line 8.
By adjusting the phase shifter 8-2 based on the control signal from -8 to change the optical path length of the ring-shaped optical resonator 8-1,
It can be tuned to any frequency channel. That is, only an arbitrary frequency channel can be connected to the output port 8-7, and the other frequency channels can be sent to the next-stage switch. By adjusting the phase shifter 8-2 for each time slot, a frequency channel can be selected at high speed.

FIG. 11 shows an example of the configuration of the frequency converter 5-3. In FIG. 11, 9-1 is a branching device, 9-2 to 9
-3 is a light receiver, 9-4 is a circuit for converting header information into a frequency channel control signal, 9-5 is a frequency variable semiconductor laser, and 9-6 is an external modulator.

After passing through the splitter 9-1, the input signal is converted into a high-speed electric signal by the photodetector 9-2 and drives the external modulator 9-6. On the other hand, the input signal monitored by the branching unit 9-1 is converted into an electric signal by the photodetector 9-3, and enters the header-frequency channel conversion circuit 9-4. The header-frequency channel conversion circuit 9-4 separates / analyzes only the header portion of the signal and sends a control signal corresponding to the frequency channel corresponding to the destination to the frequency variable semiconductor laser 9-5. This control signal causes the frequency variable semiconductor laser to oscillate at a predetermined frequency for each time slot. Thereafter, a signal is loaded and output by the driven external modulator 9-6. In this configuration, an all-optical configuration is possible as long as the optical control of the external modulator or the frequency-variable semiconductor laser can be directly controlled.

FIG. 12 shows an example of the configuration of the output signal selection circuit 6-1. In FIG. 12, 10-1-1 to 10-1
-R is a ring-shaped optical resonator, 10-2-1 to 10-2-r
Is a phase shifter, 10-3-1 to 10-3-r is a variable directional coupler, 10-4-1 to 10-4-r is a directional coupler, 1
0-5 is a multiplexer, 10-6 is an output port to an output buffer, 10-7 is a feedback signal line, 10-8 is a splitter, 10-
Reference numeral 9 denotes a duplexer, 10-10-1 to 10-10-r an address determination circuit, and 10-11 a control signal line.

In the input frequency-division multiplexed signal, in each ring-shaped optical resonator 10-1, only the channel corresponding to the resonance frequency determined by the optical path length is output to the multiplexer 10-5, and the other frequency channels are output. Is sent to the next ring optical resonator. The resonance frequency of each resonator is adjusted in advance to a predetermined frequency channel by adjusting the phase shifter 10-2. If there is no signal to be selected in each resonator, the coupling coefficient is set to 0 by the variable directional coupler 10-3, and all signals are sent to the next stage. The selected signal is output from the multiplexer 10
The output data is multiplexed to one output port 10-6 by -5 and output to an output buffer. The signal not finally selected by any of the resonators is fed back to the input module through the feedback signal line 10-7. By adjusting the variable directional coupler 10-3 for each time slot, a frequency channel can be selected at high speed.

These controls are performed as follows. The input signal monitored by the splitter 10-8 is input to the splitter 1
At 0-9, the signal is demultiplexed for each channel, and the address judgment circuit 10-
Send to 10. When the address of the signal matches the output address, the address determination circuit determines whether the variable directional coupler 10-
3 sends a control signal through control signal line 10-11 to couple to the resonator. Otherwise, a control signal is sent so as not to combine. Thus, the output signal selection circuit
For a frequency multiplexed input signal, a signal that matches the output address can be selected and sent to the output buffer, and a signal that does not match can be fed back to the input module.

FIG. 13 shows another example of the configuration of the output signal selection circuit 6-1. In FIG. 13, reference numeral 11-1 denotes a duplexer,
1-2-1 to 11-2-r are 1 × 2 optical switches, 11-
Reference numerals 3 to 11-4 denote a multiplexer, 11-5 denotes an output port to an output buffer, 11-6 denotes a feedback signal line, and 11-7-1 to 11--11.
-7-r is a branching device, and 11-8-1 to 11-8-r are address determination circuits.

The input frequency-division multiplexed signal is supplied to the splitter 11
1 × 2 optical switch 11 which is demultiplexed for each channel by -1
-2 is input. The 1 × 2 optical switch outputs a signal that matches the output address to the upper output port, and outputs a signal that does not match the output address to the lower output port. The multiplexer 11-3 multiplexes the selected signal and outputs the multiplexed signal to the output port 11-.
5 to the output buffer. Multiplexer 11-
4 combines the unselected signals and feeds them back to the input module through the feedback signal line 11-6. By switching the 1 × 2 optical switch 11-2 for each time slot, a frequency channel can be selected at high speed. These controls are performed as follows. Based on the input signal monitored for each channel by the branching unit 11-7, the address determination circuit 11-8 moves the 1 × 2 optical switch upward if the address of the signal matches the output address. If not, send a control signal to switch down.

FIG. 14 shows a frequency multiplexing type output buffer 6-6.
2 shows a configuration example. In FIG. 14, 12-1 is a branching device, 12-2 is a signal discarding output means, and 12-3-1 to 1-3-1.
2-3-3-L is a 2 × 2 optical switch, 12-4-1 to 12-
4-L is a loop-shaped optical waveguide, 12-5 is a frequency selection type 1
A × 2 switch, 12-6 is an output highway, 12-7 is a buffer control circuit, and 12-8 is a control signal line.

The input signal is input to the loop-shaped optical waveguide delay line array 12-4 and is buffered. Where 1
The loop optical waveguides 12-4 function as one buffer, and when the buffer at the next stage becomes empty, the 2 × 2 optical switch 12-3 is set to the cross state and the frequency multiplexed signal is sent to the next stage as it is. If it is not vacant, it is put in a bar state and the signal is circulated. If there is a signal input when the first stage buffer is not empty, the signal is discarded by the signal discarding output means 12-2. The buffer of the last stage controls only a predetermined frequency channel by the frequency selection type 1 × 2 switch 12-5 under the control of the buffer control circuit 12-7.
Output to the output highway 12-6. The signals of the other frequency channels are switched to the loop optical waveguide and circulated.

All of these controls are performed in advance by the branching unit 12.
This is performed based on the buffer input signal monitored by -1. The buffer control circuit 12-7 analyzes the time slot / frequency channel occupation state of the buffer input signal, and controls the operation of each switch through the control signal line 12-8. The frequency multiplexed input signals arriving at the same time are output to different time slots by the frequency multiplexed output buffer. This buffer configuration is described in "Optical Frequency Multiplexing FIFO Buffer"
174507).

FIG. 15 shows an example in which a plurality of frequency routing type time division highway switch modules are connected in multiple stages to constitute a multiterminal highway switch. FIG.
, 13-1-1 to 13-1-MN are input highways, 13-2-1 to 13-2-MN are input modules, 13-3-1 to 13-3-M are N × N frequency routers, 13-4-1 to 13-4-MN are output modules,
13-5-1 to 13-5-MN are output highways. Time division highway switch modules optical frequency routing type, each of N input highway input and output module, one N × N frequency router, and a r ^a number of extension connectors.

[0059] The difference between the switch of the one-stage configuration illustrated in FIG. 1, r ^a of the inner 0 to R ^a -1 output ports of the frequency router
The extension output terminals into individual, inner 0 to R ^a in the output module
The r ^a number of -1 is where connecting the extension input terminals. In these M switch modules, the extension output terminal of the ith module is connected to the extension input terminal of the (i + 1) th module having the same number (i = 0 to M−2). All the switch modules are connected in a ring so that the extension output terminals of the first module are connected to those having the same number of the extension input terminals of the first module. The operation of the input / output module and the arrangement of channels used by the frequency router are all the same as those in FIG. Thus, a multistage switch network can be configured.

The switch module shown in FIG.
The size of the switch network can be easily increased by inserting the switch network into the portion indicated by the dashed line.

The optical frequency routing type time division highway switch has been described above. However, it is apparent that the present invention can be applied to an optical frequency routing type interconnection network in an application field where a high-speed time division operation is not required.

As described above, in the optical frequency routing type time division highway switch of this embodiment, an input signal is not routed to a desired output highway at one time, but is input a plurality of times using a feedback signal line. Arrives at the target output highway via the output module. This is a so-called multi-hop switch configuration. Therefore, the frequency converter does not need to be able to convert the input signal to all frequency channels, and only needs to use some of the frequency channels in the frequency router. Has a feature that at most r pieces are sufficient.

[0063]

As described above, according to the present invention,
By using only a predetermined part of the channel assignment table of the frequency router and returning a part of the signal routed to the output module to the input module using a feedback signal line, a so-called multi-hop switch configuration is realized. It can be realized and the following effects can be expected.

(1) The frequency converter only needs to have an at most continuous r channel width as the conversion width, and does not require a wide band as in the prior art.

[0065] (2) the frequency channel used in the frequency ^{router, r a-1 ~2r a -r} a-1 consecutive 2
Since (r-1) r ^a-1 +1 (seed) channels, the operating band of various optical components (optical amplifiers and the like) used in the switch does not require a wide band as in the related art.

(3) Since the optical signal arriving at the output port is at most r channels, the device constituting the frequency multiplexing type output buffer does not require the wide band property and the wide dynamic property as in the related art.

The wide dynamic property means that the operation can be performed when the input light intensity fluctuates dynamically because the number of multiplexes at the time of buffer arrival varies from 0 to the maximum value for each time slot. In addition, when an optical amplifier is used to amplify frequency multiplexed optical signals in a buffer in a buffer, a signal having a high degree of multiplexing increases the input light intensity to the amplifier, and causes disadvantageous operations such as a decrease in the degree of amplification and a non-linear phenomenon. However, when the multiplicity is low, such a problem can be avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical frequency routing type time division highway switch according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of the input module shown in FIG.

FIG. 3 is a block diagram showing a configuration of an output module shown in FIG.

FIG. 4 is a waveguide layout diagram of an arrayed waveguide diffraction grating filter constituting the frequency router of FIG. 1;

FIG. 5 is a diagram showing a frequency channel assignment table of an N × N frequency router.

FIG. 6 is a diagram illustrating the use of a frequency channel in an N × N frequency router.

FIG. 7 is a diagram showing a specific example in which specific numerical values are substituted in FIG.

FIG. 8 is a diagram illustrating a specific routing in the specific example of FIG. 7;

FIG. 9 is a block diagram showing a configuration of an input buffer shown in FIG. 2;

FIG. 10 is a diagram showing a configuration of a frequency selection type 1 × 2 switch shown in FIG. 9;

11 is a block diagram showing a configuration of the frequency converter shown in FIG.

FIG. 12 is a diagram showing a configuration of an output signal selection circuit shown in FIG. 3;

FIG. 13 is a diagram showing another configuration of the output signal selection circuit shown in FIG. 3;

FIG. 14 is a diagram showing a configuration of a frequency multiplexing type output buffer shown in FIG. 3;

FIG. 15 is a diagram showing a multi-terminal highway switch configured by connecting a plurality of optical frequency routing type time division highway switch modules in multiple stages.

FIG. 16 is a block diagram showing a configuration of a switch module when the scale is increased in the highway switch shown in FIG. 15;

FIG. 17 is a block diagram showing a configuration of a conventional optical frequency routing type time division highway switch.

[Explanation of symbols]

 1-1-1 to 1-1-N Input Highway 1-2-1 to 1-2-N Input Module 1-3 Frequency Router 1-4-1 to 1-4-N Output Module 1-5-1 to 1-1 1-5-N Output Highway 5-2 Input Buffer 5-3-1 to 5-3-r Frequency Converter 5-4 Combiner 6-1 Output Signal Selection Circuit 6-2 Frequency Multiplexed Output Buffer

Claims (6)

(57) [Claims] 1. A time division highway switch for exchanging an optical signal on a plurality of time division input highways with an arbitrary output highway for each time slot, connected to each input highway and inputted from each input highway. For a maximum of r frequency-multiplexed optical signals fed back from an optical signal and an output module connected to the same numbered output highway, a maximum of r
An input buffer for synchronously outputting the optical signals, r frequency converters for assigning frequency channels to the output optical signals from the input buffer for each time slot, and merging the output optical signals from the frequency converters An input module including a merger, a frequency router for connecting an output optical signal from the input module to a specific output highway according to a frequency channel for each time slot, and an output port of the frequency router, Output signal selection for selecting only the optical signal corresponding to the destination address for each time slot with respect to the output optical signal from the frequency router and outputting it to the output line, and outputting the other optical signals to another output line Circuit, and a plurality of different optical signals present in the same time slot for the selected optical signal from the output signal selecting circuit. An output module having a frequency multiplexing type output buffer for outputting an optical signal on the wave number channel so that only one signal is present in one time slot; An optical frequency routing type time division highway switch comprising: r feedback signal lines for feeding back to an input module. 2. The frequency router includes a plurality of input optical waveguides for inputting an optical signal, a first slab optical waveguide for receiving an optical signal from the input waveguide, and the first slab optical waveguide. And a second slab-shaped light guide for receiving an optical signal from the array waveguide and receiving the optical signal from the array waveguide. 2. An optical frequency routing device according to claim 1, wherein said optical frequency routing device comprises an arrayed waveguide grating filter having a waveguide and a plurality of output optical waveguides for receiving and outputting an optical signal from said second slab-shaped optical waveguide. Type time sharing highway switch. 3. The frequency router has N inputs and N outputs, and (N−p + q) mod N (where N, p and q are integers, and 0 ≦ p, q ≦ N−1). 2. The optical frequency routing type time division highway switch according to claim 1, wherein each optical signal having the following frequency channel number is connected from the input port p to the output port q. Wherein said frequency router, N inputs and N outputs (where, N = ar ^a, and a, r is an arbitrary positive integer) have, ## EQU2 ## (N- (ir ^a + j) + (((i + 1) mod a) r a + (jmod r a-1) r + m)) mod N (i, j, m is an integer, 0 ≦ i ≦ a-1,0 ≦ j ≦ r a - 1, 0 ≦ m ≦ r−1) Each optical signal having a frequency channel number represented by the following equation is input from an input port (ir ^a + j) to an output port ((i + 1) mod a) r
^2. The optical frequency routing type time-division highway switch according to claim 1, wherein the optical frequency routing type time-division highway switch is connected to r consecutive numbers of ^a + (jmod ra ^-1 ) r + m). 5. A time-division highway switch for exchanging optical signals on N time-division input highways with an arbitrary output highway for each time slot, comprising: an optical signal from each input highway and an output highway having the same number. N input module for processing on the feedback optical signal from the output module connected, N-input N-output frequency router connected to the input module (where, N = ar ^a, and a, r Is any positive integer)
And some output ports s (0 ≦ s ≦ r
and r ^a number of extended output terminal connected to ^a -1), r ^a
And N output modules connected to the output highway and the output terminals for expansion or the remaining output ports t (r ^a ≦ t ≦ N−1) of the frequency router; M optical frequency routing type time division highway switch modules comprising: a first optical frequency routing type time division highway switch module, and an output terminal for expansion is a second optical frequency routing type time division highway switch module. The extension output terminal of the second optical frequency routing type time division highway switch module is connected to the same number of the extension input terminal of the module, and the extension output terminal of the third optical frequency routing type time division highway switch module. Each of the extension input terminals is connected to the same number, and finally the M-th optical frequency Expanded output terminal of the quenching type time division highway switch modules, said first
Optical frequency routing type time-division highway switch module, wherein M optical frequency routing type time-division highway switch modules are connected in an annular manner by being connected to the same number of expansion input terminals. Routing type time division highway switch. 6. The optical frequency routing type time division highway switch module is newly provided with the M-th optical frequency routing type time division highway switch module.
6. The optical frequency routing type time division highway switch according to claim 5, wherein the switch scale is expanded by being inserted between the optical frequency routing type time division highway switch module and the optical frequency routing type time division highway switch module.