JPH07121140B2 - WDM optical switching circuit - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing optical switching circuit for performing switching connection using optical signals.

(Prior art and its problems) In recent years, so-called multifunctional terminals having not only a conventional telephone service but also a transmission / reception function for moving images, still images and various high-speed data have been developed along with the complexity of office work. .

In such a multi-function terminal, because the bandwidth of the signal to be transmitted and received dozens MH _Z several MH _Z, instead inexpensive fiber optic cable to a conventional coaxial cable as a transmission line connecting these multifunctional terminal to each other Is being considered.

Therefore, in order to organically combine such multifunctional terminals and provide a wide range of advanced services, optical signals can be exchanged without changing the broadband signals transmitted and received between the multifunctional terminals. Circuits are essential.

On the other hand, in order to cope with future telephone demand, in recent years, optical cables that have advantages such as small diameter, wide band, low loss, and electromagnetic induction resistance have been replaced with conventional coaxial cables for local relay systems and long distance transmission systems. The fiber cable transmission system has been introduced.

However, at present, in so-called repeater exchanges that perform mutual exchange connection between the channels on the optical transmission line, optical signals sent by an optical fiber cable are converted into electrical signals and then exchange connection is performed. Then, it is converted into an optical signal again and sent to the optical fiber cable.

Therefore, in the above-mentioned repeater switch, an electric-optical conversion circuit or an optical-electrical conversion circuit is required for each optical fiber cable.

Therefore, an object of the present invention is to enable wideband signals to be exchanged between subscriber terminals to be exchanged as optical signals.
An object of the present invention is to provide a wavelength division multiplexing optical switching circuit capable of performing mutual switching connection between channels between optical transmission lines without using an electrical conversion circuit and an electrical-optical conversion circuit without changing the optical signal.

(Means for Solving Problems) Means provided by the first invention of the present application in order to solve the above problems is a wavelength λ ₁ , λ _2, ... , Λ _n optical signals are wavelength-division-multiplexed, the first wavelength-division multiplexed optical signal is received at the input, and the n pieces of call information are respectively received as first wavelength-division multiplexed optical signals according to control information. different wavelength λ ₁ is the wavelength of, λ ₂ ···,
A first switching stage consisting of m number of wavelength conversion switches which outputs the wavelength-division-multiplexed second wavelength-division-multiplexed optical signal by substituting for λ _n, and m wavelength conversions of the first exchange-stage. M demultiplexers connected to the outputs of the switches and m optical signals of the same wavelength output from the m demultiplexers are respectively wavelengths λ ₁ , λ ₂ ,. n wavelength conversion means composed of m wavelength conversion elements for converting the optical signals of λ _{m, and} the optical signals of wavelengths λ ₁ , λ _2, ..., λ _m output from the wavelength conversion means, respectively. N multiplexers that are division-multiplexed and output as third wavelength division multiplexed signals, and wavelengths λ ₁ and λ that are respectively modulated by m pieces of call information output from the n multiplexers. ₂ ..., λ
_m wavelength-division-multiplexed wavelength-division-multiplexed optical signals are input to the input, and the m pieces of call information are respectively wavelengths of the third wavelength-division-multiplexed optical signals according to control information. , Λ _m , which are different from the wavelengths λ ₁ , λ _2, ..., λ _m, and wavelength-division-multiplexed optical signals of wavelengths λ ₁ , λ _2, ..., λ _m. At least a second conversion stage composed of n wavelength conversion switches for outputting as a signal is included.

In order to solve the above-mentioned problems, the means proposed by the second invention of the present application is that the wavelength conversion switch has wavelengths λ ₁ , λ _2, ..., λ respectively modulated by k pieces of call information. _k
And a wavelength selection circuit for receiving and outputting a first wavelength division multiplexed optical signal obtained by wavelength division multiplexing the optical signal , K wavelength conversion elements for converting the optical signals output from the k outputs of the wavelength selection circuit into optical signals of wavelengths λ ₁ , λ _2, ..., λ _k , respectively, and the _k optical signals. And a multiplexer having an input connected to the output of the conversion element.

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

FIG. 1 is a block diagram showing an embodiment of the first invention of the present application.

According to FIG. 1, in the present embodiment, the wavelength conversion switches 101, 102, 103, 104 constituting the exchange stage 100, the wavelength conversion switches 106, 107, 108 constituting the exchange stage 105, and the demultiplexers whose inputs are connected to the outputs of the wavelength conversion switches 101, 102, 103, 104, respectively. Units 109, 110, 111, 112 and wavelength conversion switches 106, 1 respectively
It includes multiplexers 113, 114 and 115 whose outputs are connected to the inputs of 07 and 108.

Further, according to FIG. ₁ , the optical signals having the wavelength λ ₁ are selected from the outputs of the demultiplexers 109, 110, 111 and 112, respectively, as the inputs of the multiplexer 113, and the wavelengths λ ₁ , λ ₂ and λ ₂ are selected by the wavelength conversion elements 116, 117, 118 and 119, respectively. After being converted into an optical signal having λ ₃ and λ ₄ , it is added to the input of the multiplexer 113. Similarly multiplexer 11
The wavelength conversion elements 120, 121, 122, and 1 are also input to 4,115, respectively.
23 and 124, 125, 126, 127 are provided.

In FIG. 1, the wavelength conversion elements 116, 121 and 126 have the same input and output wavelengths, and it is not necessary to provide a wavelength conversion element in particular, but here, each wavelength λ _i is converted into the same wavelength λ _i . Wavelength conversion element 116,
The description will proceed assuming that 121 and 126 are provided.

FIG. 2 shows the wavelength conversion switches 101, 102, 10 shown in FIG.
It is a block diagram showing a concrete example of 3,104.

The wavelength selection circuit 200 shown in FIG. 2 selects an optical signal of any wavelength of the wavelength multiplexed optical signals having the wavelengths λ ₁ , λ ₂ and λ ₃ on the input highway 205 in accordance with the control signal 210 and selects the wavelengths respectively. It is added to the inputs of the conversion elements 201, 202 and 203. The wavelength selection circuit 200 can be constructed by using, for example, a LiNbO ₃ waveguide type optical wavelength tunable filter described in Proceedings of the 42nd Japan Society of Applied Physics 9P-M-9. In addition, the wavelength conversion element 201,
Reference numerals 202 and 203 convert an optical signal of an arbitrary wavelength applied to the input into an optical signal having wavelengths λ ₁ , λ ₂ and λ ₃ , respectively. As this wavelength conversion element, the IEEE Journal of QE vol QE
-14, No.11.Nov1978p810 to 813, "pnnpn Optical Detectors and Light Emitting Dies" (pnpnn Optical Detectors an)
d Light-Emitting Diodes) may be used, but in principle, this wavelength conversion element cannot convert an optical signal with a long wavelength into an optical signal with a short wavelength. As the wavelength conversion element 201, 202, 203,
For example, once a non-linear optical crystal such as a LiNbo ₃ crystal is used to generate a harmonic optical signal having a wavelength shorter than any one of the wavelengths λ ₁ , λ ₂ , and λ ₃ , the above-mentioned “p-n-p-n” is generated. A means for converting into optical signals having wavelengths λ ₁ , λ ₂ , λ ₃ by a wavelength conversion element as described in “Optical Detectors and Light Emitting Diodes” is conceivable.

The multiplexer 204 multiplexes the optical signals of the wavelengths λ ₁ , λ ₂ , λ ₃ obtained at the outputs of the wavelength conversion elements 201, 202, 203, and outputs the output highway.
Send to 206.

Wavelengths λ ₁ , λ ₂ , λ ₃ on the input highway 205 are respectively on channels 1, 2, 3 and wavelengths λ ₁ , λ ₂ , on the output highway 206.
λ ₃ corresponds to channels 1, 2 and 3, respectively, and the second
The wavelength conversion switch shown in the figure describes an example in which a communication path is set between the incoming channel 1 and the outgoing channel 3 and between the incoming channel 3 and the outgoing channel 1.

That is, the wavelength selection circuit 200 selects the optical signal of the wavelength λ ₁ on the input highway 205 according to the control signal 210 and adds it to the input of the wavelength conversion element 203.
Is converted into an optical signal having a wavelength λ ₃ and then transmitted to the output highway 206 via the multiplexer 204. At the same time, the wavelength selection circuit 200 selects the optical signal of the wavelength λ ₃ on the input highway 205 and adds it to the input of the wavelength conversion element 201, and this optical signal is converted by the wavelength conversion element 201 into an optical signal having the wavelength λ _1. Then, it is sent to the output highway 206 via the multiplexer 204.

In this way, a communication path is formed between the incoming channel 1 and the outgoing channel 3 and between the incoming channel 3 and the outgoing channel 1 shown in FIG.

The embodiment shown in FIG. 1 is a wavelength division multiplexing optical switching circuit that forms an arbitrary communication path between 12 input / output channels using the wavelength conversion switch shown in FIG. An example of setting a communication path between the channel 1 of the highway 128 and the channel 3 of the output highway 129 is described.

That is, the wavelength conversion switch 101 receives the wavelength λ on the input highway 128 according to a command from a control circuit (not shown).
After converting the optical signal of _{1 into} the optical signal of wavelength λ ₃ , the demultiplexer 10
Add to the input of 9. This optical signal was further converted by the wavelength conversion element 124 into an optical signal of wavelength λ ₁ and then applied to the input of the wavelength conversion switch 108 through the multiplexer 115. Finally, this optical signal is transmitted by the wavelength conversion switch 108 to the wavelength λ ₃
After being converted into an optical signal of, the signal is sent to the output highway 129.

Thus, the wavelength division multiplexing optical switching circuit shown in FIG.
Channel 1 on input highway 128 and output highway 1
A communication device that propagates a wide band optical signal is set between the upper channel 29 and the channel 3.

Further, in the wavelength division multiplexing optical switching circuit of FIG. 1, four wavelengths λ ₁ ,
12 input / output channels can be arbitrarily connected by λ ₂ , λ ₃ , λ _4, and many input / output channels can be connected by a limited number of optical wavelengths. .

(Effects of the Invention) As described above, according to the invention of the present application, it is possible to obtain an optical switching circuit capable of exchanging a broadband signal transmitted and received between terminals as optical. Furthermore, the optical switching circuits according to these inventions have the advantage that many terminals can be connected by a limited number of optical wavelengths.

In each of the embodiments shown in FIG. 1, an example in which a wavelength division multiplexing optical switching circuit is configured by two switching stages is shown for simplification of description, but it is usually three or more conversion stages. It is often configured by

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the first invention of the present application, and FIG. 2 is a wavelength conversion switch 10 in the embodiment of FIG.
It is a block diagram which shows the specific example of 1,102,103,104. 101-108 …… Wavelength conversion switch, 109-112 …… Separator,
113-115,204 ... Multiplexer, 116-127,201-203 ... Wavelength conversion element, 200 ... Wavelength selection circuit.

Claims (2)

[Claims] 1. A first wavelength division multiplexed optical signal obtained by wavelength division multiplexing optical signals of wavelengths λ ₁ , λ _2, ..., λ _n respectively modulated by n pieces of call information. In response to the control information, the n pieces of call information are respectively wavelengths λ ₁ , λ _2, ..., Different from the wavelength of the first wavelength division multiplexed optical signal.
A first switching stage consisting of m number of wavelength conversion switches which outputs the wavelength-division-multiplexed second wavelength-division-multiplexed optical signal by substituting for λ _n, and m wavelength conversions of the first exchange-stage. M demultiplexers connected to the outputs of the switches and m optical signals of the same wavelength output from the m demultiplexers are respectively wavelengths λ ₁ , λ ₂ ,. n wavelength conversion means composed of m wavelength conversion elements for converting the optical signals of λ _{m, and} the optical signals of wavelengths λ ₁ , λ _2, ..., λ _m output from the wavelength conversion means, respectively. N multiplexers that are division-multiplexed and output as a third wavelength-division-multiplexed optical signal, and wavelengths λ ₁ respectively modulated by m pieces of call information output from the n multiplexers, λ ₂ ...
A third wavelength division multiplexed optical signal obtained by wavelength division multiplexing the optical signal of λ _m is received at the input, and the third m
Each piece of call information is transferred to wavelengths λ ₁ , λ _2, ..., λ _m different from the wavelength of the third wavelength division multiplexing optical signal,
At least a second conversion stage consisting of n wavelength conversion switches for outputting as a fourth wavelength division multiplexed optical signal obtained by wavelength division multiplexing optical signals of wavelengths λ ₁ , λ _2, ..., λ _m. A wavelength division multiplex switching circuit comprising: 2. A _first wavelength division multiplex wherein the wavelength conversion switch wavelength-division-multiplexes optical signals of wavelengths λ ₁ , λ _2, ..., λ _k respectively modulated with k pieces of call information. A wavelength selection circuit that receives the converted optical signal as an input and selectively outputs an optical signal having a wavelength corresponding to the control signal to each of the k outputs,
K wavelength conversion elements for converting the optical signals output from the k outputs of the wavelength selection circuit into optical signals of wavelengths λ ₁ , λ _2, ..., λ _k respectively, and the _k optical conversion elements. The wavelength division multiplexing switching circuit according to claim 1, further comprising a multiplexer having an input connected to an output of the element.