JP2983596B2 - Time division / wavelength division fusion switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a time division / wavelength division multiplex switch used in optical switching for exchanging optical information from an optical fiber transmission line as light, using a small wavelength variable optical memory, time division / wavelength multiplexing. It is intended to switch m information, and to accommodate m highways that are time-division multiplexed with a multiplicity of n and wavelength division multiplexed with a multiplicity of m, respectively. A 1 × m optical switch corresponding to each wavelength and provided for m demultiplexers,
An m × n optical switch provided on the output line side of the m optical switch, and one m × n optical switch provided on the output line side of each m × n optical switch.
a wavelength-variable optical memory provided for n optical switches, an n × 1 optical switch for receiving an output from the n wavelength-variable optical memory groups on the input line side, and a coupler for each output highway; The output line of the optical switch is connected to the input line of an m × n optical switch of a different wavelength on the same highway, and each of the n ×
The output of one optical switch is connected to the coupler of another highway.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switch used in optical switching for exchanging optical information from an optical fiber transmission line as light, and in particular, to a plurality of time division multiplexed and wavelength multiplexed information on a highway. The present invention relates to a time division / wavelength division fusion switch for switching.

[Prior Art] FIG. 3 is a block diagram showing a conventional time division / wavelength division fusion switch. In FIG. 3, 1 is time division multiplexed (time slots TS1 to TSn) at a multiplicity of n. And wavelength division multiplexing at a multiplicity m (wavelengths λ _{1 to} λ _m )
In this highway, m highways 1 are provided.

In addition, 2 is provided for each entrance highway 1 and W &
A T (wavelength and time) switch 3 is connected to each W & T switch 2 and is a demultiplexer that demultiplexes the output of each switch 2 to each of the wavelengths λ _{1 to} λ _m. Different wavelength λ
₁ to [lambda] _m combiner for combining outputs one by one subjected to a, 5 is the outlet side of the W & T switches provided for each highway 6 out each connected to each coupler 4.

As shown in FIG. 3, the conventional time division / wavelength division switch has a two-stage configuration of W & T switches 2,5. Each of the W & T switches 2,5 is shown in FIG. It is configured as shown. In FIG. 4, reference numeral 7 denotes a demultiplexer provided for each input highway 1 or each coupler 4, and 8 denote _m demultiplexers corresponding to the wavelengths λ _{1 to} λ _m demultiplexed by the demultiplexers 7, respectively. The provided 1 × n optical switches 9 are provided on the outgoing line side of the 1 × n optical switch 8 and provided with n (m in total) wavelength tunable optical memories (optical devices) for one 1 × n optical switch 8. Bistable semiconductor laser), 10 is n wavelength tunable optical memories 9
N × 1 optical switch receiving the output from the group of
Is a coupler for receiving the outputs of the m n × 1 optical switches 10.

FIG. 5 shows a space division equivalent circuit of the conventional time division / wavelength division fusion switch as described above. In other words, the switches shown in FIG. 3 are mn × mn input-side switches 12 provided for each input highway, and mn × switches provided for each output highway.
It can be regarded as equivalent to a configuration in which the output switch 13 of mn is linked to each other.

With such a configuration, an optical signal coming from each incoming highway 1 is output to a desired outgoing highway 6 by the first stage W & T switch 2 (however, only n out of mn). . Then, the signal is converted into a desired time slot and wavelength by the second stage W & T switch 5.

[Problems to be Solved by the Invention] However, in such a conventional time division / wavelength division fusion switch, mn number of tunable optical memories 9 are required for each of the two-stage W & T switches 2 and 5. There is a problem in that the entire switch requires as many as 2mn ² tunable optical memories 9.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has a time division / wavelength division switch capable of reliably switching time division multiplexed and wavelength multiplexed information with a smaller number of wavelength tunable optical memories. It is intended to provide.

[Means for Solving the Problems] FIG. 1 is a principle block diagram of the present invention.

In FIG. 1, reference numeral 1 denotes m incoming highways, 6 denotes m outgoing highways, and these highways 1 and 6 are respectively time-division multiplexed at a multiplicity of n and wavelength-division multiplexed at a multiplicity of m. ing. 14 is each incoming highway 1
A 1 × m optical switch provided for each of the demultiplexers 14 corresponding to the wavelengths λ _{1 to} λ _m demultiplexed by each of the demultiplexers 14; Is a 1 × m optical switch 15
M × n optical switches provided on the outgoing line side of
N tunable optical memories provided on the output line side of the optical switch 16 and provided for n mxn optical switches 16;
An n × 1 optical switch for receiving the output from the group of wavelength tunable optical memories 17 on the input side, and 19 is a coupler provided for each output highway 6.

And the outgoing line of the 1 × m optical switch 15 is the same highway
The outputs of the n × 1 optical switches 18 are connected to the input lines of the m × n optical switches 16 of different wavelengths on
It is connected to the combiners 19 of 1,6.

[Operation] In the above-described time division / wavelength division fusion switch of the present invention,
The outgoing line of the 1 × m optical switch 15 is connected to the incoming line of the m × n optical switch 16 of a different wavelength on the same highways 1 and 6, and each of the n ×
The output of one optical switch 18 is connected to the coupler 1 of each of the highways 1 and 6.
By connecting to 9, switching of optical signals between highways can be realized in addition to time slot and wavelength conversion (however, only n out of mn).

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

FIG. 2 is a block diagram showing one embodiment of the present invention. In this embodiment, as shown in FIG. 2, when the time multiplicity n = 8 and the wavelength multiplicity (the number of highways) m = 4, , Each of which accommodates four highways 1 and 6 that are time-division multiplexed at a multiplicity of 8 and wavelength division multiplexed at a multiplicity of 4.
The wavelength division fusion switch will be described.

As shown in FIG. 2, a demultiplexer 14 is provided for each incoming highway 1.
A is provided, and the input signal is converted to a wavelength λ by the duplexer 14A.
Is adapted to be ₁ to [lambda] ₄ demultiplexed. Also, 1 × 4
The optical switch 15A receives the wavelengths λ _1-
Four switches are provided for one demultiplexer 14A corresponding to each λ ₄ , and a 4 × 8 optical switch 16A is provided on the output side of each 1 × 4 optical switch 15A. Further, on the outgoing line side of each 4 × 8 optical switch 16A, eight tunable optical memories 17 are provided for one 4 × 8 optical switch 16A, and the output from the eight tunable optical memories 17 is , 8 × 1 optical switch 18
Input to the incoming line of A. In addition, 19A is each highway 6
It is a coupler provided for each.

The outgoing line of the 1 × 4 optical switch 15A is connected to the incoming line of the 4 × 8 optical switch 16A of a different wavelength on the same highway 1,6, and the output of each 8 × 1 optical switch 18A is connected to the different highway 1,6. 6 are connected to the coupler 19A.

With the above-described configuration, three types of time slot conversion, wavelength conversion, and switching of optical signals between the highways are performed.

First, time slot conversion is performed as follows. That is, for example, an optical signal from the input highways ♯1 (λ _1, TS1), in the demultiplexer 14A, is branched to the output port of the wavelength lambda _1, the 1 × 4 optical switch 15A corresponding to the wavelength lambda ₁ This optical signal is connected to the output highway # 1 by high-speed switching in units of time slots.
It is switched so as to be sent to the × 8 optical switch 16A. In the 4 × 8 optical switch 16A, the optical signal is changed to a wavelength-variable optical memory in which no optical signal is input (vacant) by high-speed switching in time slot units.
Switched to 17. In the wavelength tunable optical memory 17, an optical signal is held for one frame (for eight time slots). Here, the function of the tunable optical memory 17 is exhibited by the optical bistable semiconductor laser. That is, when an optical pulse is input (set signal), the optically bistable semiconductor laser starts laser oscillation, and when a negative pulse current is input (reset signal), the optical flip-flop stops oscillating. It is working. Further, the optical signal held (oscillated) in the wavelength tunable optical memory 17 is
In the 8 × 1 optical switch 18A, a desired output time slot (for example,
TS8). The optical signal of the wavelength λ ₁ is combined with the optical signal of another wavelength (λ ₂ , λ ₃ , λ ₄ ) by the coupler 19A on the same highway # 1 and transmitted.
Time slot conversion is performed. here,
The signal flow in the above case is indicated by a solid arrow shown in FIG.

The switching of the optical signal between the highways is as follows. That is, for example, the optical signal (λ ₁ , TS1) from the input highway # 1 is input to the splitter 14A at the wavelength λ
₁ × 4 corresponding to wavelength λ ₁
In the optical switch 15A, this optical signal is switched so as to be transmitted to the 4 × 8 optical switch 16A connected to the output highway # 4 by high-speed switching in units of time slots. Then, in the 4 × 8 optical switch 16A, the optical signal is switched to the tunable optical memory 17 to which the optical signal is not input by the high-speed switching in time slot units. In this wavelength tunable optical memory 17,
The optical signal is held for one frame. Here, when an optical pulse is input, the optical bistable semiconductor laser (wavelength variable optical memory 17) starts laser oscillation, and when a negative pulse current is input, it operates so as to stop the oscillation. wavelength of the oscillation light can be set to a desired value by varying the current of the wavelength variable region of the tunable optical memory 17, the wavelength of the optical signal is converted, for example, lambda _4. Further, the optical signal held in the wavelength variable optical memory 17 is switched to a desired output time slot (for example, TS8) by the 8 × 1 optical switch 18A by high-speed switching in units of time slots. The optical signal of the wavelength λ ₄ is combined with the optical signal of another wavelength (λ ₁ , λ ₂ , λ ₃ ) by the coupler 19A on the output highway # 4 and transmitted, and the optical signal between the highways is output. Signal switching is performed. Here, the signal flow in the above case is indicated by a dotted arrow shown in FIG.

Further, the wavelength conversion is performed as follows. That is, for example, the optical signal (λ
_1, TS1), in the demultiplexer 14A, is branched to the output port of the wavelength lambda _1, 1 × 4 optical switch 15A corresponding to the wavelength lambda ₁
The optical signal is switched so as to be transmitted to the 4 × 8 optical switch 16A connected to the output highway # 1 by high-speed switching in units of time slots. Then, in this 4 × 8 optical switch 16A, the optical signal is
By high-speed switching in units of time slots, switching is performed to the tunable optical memory 17 to which no optical signal is input. In this wavelength variable optical memory 17, an optical signal is held for one frame. Here, when an optical pulse is input, the optical bistable semiconductor laser (wavelength variable optical memory 17) starts laser oscillation, and when a negative pulse current is input,
Operates such that the oscillation stops, also the wavelength of the oscillation light can be set to a desired value by varying the current of the wavelength variable region of the tunable optical memory 17, is converted for example to the wavelength lambda _2. Further, the optical signal held in the wavelength tunable optical memory 17 is switched to a desired output time slot (for example, TS1) in the 8 × 1 optical switch 18A by high-speed switching in time slot units. Then, the optical signal of the wavelength lambda ₂ are coupler 19A on the output highway ♯1
Is coupled with an optical signal of another wavelength (λ ₁ , λ ₃ , λ ₄ ) and transmitted, and the wavelength is converted.

In this way, the output line of the 1 × 4 optical switch 15A is connected to the input line of the 4 × 8 optical switch 16A of a different wavelength on the same highways 1 and 6, and the output of each 8 × 1 optical switch 18A is connected to a different highway. By connecting to the 1 and 6 couplers 19A, the one-stage configuration of this switch can realize conversion of time slots and wavelengths, and switching of optical signals between highways.

Here, the required number of optical elements is shown in Table 1 below in comparison with the conventional configuration and the present invention. Table 1 below shows a case where the time multiplicity is n and the wavelength multiplicity is m.

As shown in Table 1 above, in the configuration of the present invention, m × n optical switches 16 and 16A are required, and the number of optical switches increases, but the number of tunable optical memories 17 as key devices is half that of the conventional configuration. The present invention is advantageous in terms of cost.

The space division equivalent circuit of the time division / wavelength division fusion switch of the present invention is the same as the conventional one shown in FIG.

[Effects of the Invention] As described above in detail, according to the time division / wavelength division fusion switch of the present invention, a duplexer, a 1 × m optical switch, an m × n optical switch, a wavelength variable optical memory, and an n × 1 optical switch A switch and a coupler are provided, and the outgoing line of the 1 × m optical switch is connected to the incoming line of an m × n optical switch of a different wavelength on the same highway.
By connecting the outputs of one optical switch to the couplers of different highways, there is an effect that a plurality of time division multiplexed and wavelength multiplexed information can be reliably switched with a smaller number of wavelength variable optical memories than in the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the principle of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, FIG. 3 is a block diagram showing a conventional example, and FIG. FIG. 5 is a block diagram showing a conventional example of a space division equivalent circuit of a configuration of a T switch. In the figure, 1 is an incoming highway, 6 is an outgoing highway, 14,14A is a duplexer, 15 is a 1 × m optical switch, 15A is a 1 × 4 optical switch, 16 is an m × n optical switch, and 16A is 4 × 8. An optical switch, 17 is a wavelength variable optical memory, 18 is an n × 1 optical switch, 18A is an 8 × 1 optical switch, and 19 and 19A are couplers.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04Q 3/52

Claims (1)

(57) [Claims] A highway (1,6) which is time-division multiplexed at a multiplicity n and wavelength-division multiplexed at a multiplicity m.
Division / wavelength division fusion switch accommodating m lines, a duplexer (14, 14A) provided for each input highway (1)
1 × m optical switches (15, 15A) provided corresponding to the wavelengths demultiplexed by the respective demultiplexers (14, 14A) and provided for each of the m demultiplexers (14, 14A). M provided on the outgoing line side of the 1 × m optical switch (15, 15A)
× n optical switches (16, 16A), and one provided on the outgoing line side of each m × n optical switch (16, 16A).
N wavelength tunable optical memories (17) provided for two m × n optical switches (16, 16A), and an n × 1 optical switch for receiving the output from the n number of wavelength tunable optical memories (17) on the input side (18, 18A) and couplers (19, 19A) provided for each output highway (6).
A), and the output lines of the 1 × m optical switch (15, 15A) are m × n optical switches (16, 16A) of different wavelengths on the same highway (1, 6).
The output of each n × 1 optical switch (18, 18A) is connected to a coupler (19, 19A) of another highway (1, 6), respectively. Wavelength division fusion switch.