JPH0754988B2 - Wavelength division type optical switching communication path - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] A wavelength converter that inputs an optical signal of any one of wavelengths λ _{1 to} λ _n and outputs an optical signal of a specific wavelength is provided, and wavelengths λ _{1 to} λ of an input highway are provided. The wavelength-division-multiplexed optical signal of _n is demultiplexed, and the optical signal is added to the wavelength converter selected by the optical switch to be converted into an optical signal of another wavelength, and the output of each wavelength converter is combined. The wavelength-multiplexed optical signal is output to the output highway to switch between wavelengths.

[Industrial application field]

The present invention relates to a wavelength division type optical switching communication path which realizes conversion of a wavelength multiplexed optical signal into a desired wavelength of an optical signal of each wavelength.

Various methods have been proposed in which an audio signal, an image signal, various data, etc. are transmitted as an optical signal, and an optical switch is used for switching connection. Further, in order to improve the multiplicity of the transmission line, a method of transmitting the wavelength-multiplexed optical signal has been developed. With respect to such a wavelength-multiplexed optical signal, it is also demanded to perform switching connection by an optical switch.

[Conventional technology]

An optical switch for switching connection of wavelength-multiplexed optical signals requires a wavelength division type optical switch for switching connection of optical signals corresponding to wavelengths. Conventionally, for example, as shown in FIG. 5, a wavelength-multiplexed optical signal of wavelengths λ _{1 to} λ _n is input from an input highway, demultiplexed by a demultiplexer 21 in accordance with the wavelength, and then transmitted to a wavelength converter 22. In addition, the wavelength-converted optical signal is multiplexed by the multiplexer 23, and an optical signal in which the wavelengths λ ₁ to λ _n are multiplexed is output to the output highway.

In that case, are read out control information written from the controller (not shown) in the control memory 24 is controlled wavelength converter 22, for example, any wavelength lambda ₁ to [lambda] _n the optical signal of the wavelength lambda ₁ It is converted into a wavelength and output. That is, an optical signal of a certain wavelength on the input highway is converted to an optical signal of the same or another wavelength, multiplexed, and transmitted to the output highway.

FIG. 6 shows a block diagram of the conventional wavelength converter shown in FIG. 5 and shows the wavelength λ demultiplexed by the demultiplexer 21.
An optical signal of _i (i = 1 to n) is converted into an electric signal by a light receiving element 30 including a photodiode, a phototransistor, etc., and a light emitting diode corresponding to the wavelengths λ _{1 to} λ _n, a light emitting element 31 such as a semiconductor laser. Added to 3n. Each light emitting element 31
~3n is controlled according to the control information read from the control memory 24, which is output is converted into any one of an optical signal having a wavelength in the wavelength lambda ₁ to [lambda] _n, applied to the multiplexer 23.

At present, a configuration for selectively generating optical signals of different wavelengths with one light emitting element has not been realized, so that the light emitting elements 31 to 3n corresponding to the wavelengths λ _{1 to} λ _n are provided as described above. Become.

[Problems to be solved by the invention]

The wavelength converter 22 in the above-mentioned conventional example has wavelengths λ _{1 to} λ _n.
Since the corresponding light emitting elements 31 to 3n are required, the total number of light emitting elements is n × n. Therefore, there is a drawback that the configuration of the wavelength division type optical switching call is complicated and expensive.

Also, after converting the optical signal into an electrical signal with the light receiving element 30, the wavelength λ
_Since the light is distributed to the light emitting elements 31 to 3n corresponding to _{1 to} λ _n , the wiring length of the electric part becomes long and the band limitation due to the stray capacitance affects the band width of the light. It was

[Means for solving problems]

The wavelength division type optical switching communication path of the present invention includes a demultiplexer for demultiplexing wavelength-multiplexed optical signals of wavelengths λ ₁ to λ _n from an input highway, and an optical signal demultiplexed by the demultiplexer. A space division type optical switch composed of optical switches corresponding to wavelengths λ ₁ to λ _{n for} switching and outputting and optical signals of different wavelengths from the optical switches corresponding to wavelengths λ _{1 to} λ _n are combined and multiplexed. The first multiplexer and the optical signals multiplexed by the first multiplexer are different wavelengths λ ₁ to
A wavelength converter for converting to an optical signal of λ _n , and a second combination for multiplexing optical signals of different wavelengths λ _{1 to} λ _n from this wavelength converter and outputting a wavelength multiplexed optical signal to an output highway. It is equipped with a wave device.

[Action]

The wavelength multiplexed signal of the wavelengths λ _{1 to} λ _n of the input highway is
The optical signals of the respective wavelengths are demultiplexed by the demultiplexers, and the optical signals of the respective wavelengths are switched and connected by the wavelength-corresponding optical switch of the space division type optical switch controlled according to the control information. Optical signals of different wavelengths from the optical switch are combined, converted into optical signals of different predetermined wavelengths by the wavelength converter, and combined by the second multiplexer to become a wavelength multiplexed optical signal. For example, the optical signal of wavelength λ ₁ demultiplexed by the demultiplexer is input to the second multiplexer selected by the optical switch, and combined with the optical signals of other wavelengths by the second multiplexer. And converted to a certain wavelength by a wavelength converter corresponding to this second multiplexer,
Since it is multiplexed by the second multiplexer, it becomes a wavelength multiplexed optical signal.

〔Example〕

 A detailed description will be given below with reference to the drawings.

Is In Figure 1, the wavelength-multiplexed optical signal of the wavelength lambda ₁ to [lambda] _n is input to the demultiplexer 1 by an input highway and an optical fiber, is the wavelength lambda ₁ to [lambda] _n demultiplexing, space division type It is input to the optical switch 2. This space division type optical switch 2
Is controlled according to the control information read from the control memory 5, for example, an optical signal of wavelength lambda ₁ is applied to the wavelength converter 3 which outputs an optical signal of wavelength lambda _n, also the optical signal of the wavelength lambda _n is , The optical signal of wavelength λ ₁ on the input highway is added to the wavelength converter 3 that outputs the optical signal of wavelength λ _1.
n , and the optical signal of wavelength λ _{n on} the input highway has wavelength λ ₁
Will be replaced respectively. Since the optical signals from the respective wavelength converters 3 are multiplexed by the multiplexer 4, wavelength multiplexed optical signals of wavelengths λ _{1 to} λ _n are sent to the output highway.

Therefore, by controlling the space division type optical switch 2, it is possible to switch the optical signal wavelength of the input highway to a different wavelength and output it to the output highway.

FIG. 2 shows a block diagram of the wavelength converter 3 described above. Reference numeral 11 is a light-receiving element for converting optical signals of wavelengths λ _{1 to} λ _n into electrical signals, and 12 is a specific wavelength λ _i (i = 1). To n) are light emitting elements that output the optical signals. Since the light receiving element 11 can convert an optical signal in a relatively wide wavelength range into an electric signal, even if the optical switch 2 selects an optical signal of any one of the wavelengths λ ₁ to λ _n , it must be converted into an electric signal. This makes it possible to drive the light emitting element 12 and output an optical signal having a predetermined wavelength.

The wavelength exchanger 3 can also be configured by using a photoexcited semiconductor laser or the like.

FIG. 3 is an explanatory view of an optical switch. For example, on a substrate 14 made of LiNbO ₃ , a waveguide 14 is formed by diffusing Ti, electrodes 15 and 16 are provided near the intersection, and an electrode 16 is formed. When grounded and a voltage is applied to the electrode 15 from the terminal 17, the refractive index at the crossing point of the waveguide 14 changes, and the condition of total reflection can be formed. Is output as. When no voltage is applied to the terminal 17, the incident light goes straight and is output as transmitted light. Therefore, the incident light can be switched and connected depending on whether or not the voltage is applied to the terminal 17.

The space division type optical switch 2 can be constructed by integrating a plurality of such optical switches on a LiNbO ₃ substrate. Alternatively, the space division type optical switch 2 can be configured by using an optical switch of a directional coupling type or a Bragg diffraction type.

However, the optical switch generally has wavelength dependence. Therefore, the present invention has the configuration shown in FIG. That is, the 1 × n optical switches 22-1 to 22-n corresponding to the wavelengths λ _{1 to} λ _n constitute a space division type optical switch. At the same time, 21 is a demultiplexer, 23-1 to 23-n are first multiplexers, 24-1 to 24-n are wavelength converters corresponding to wavelengths λ _{1 to} λ _n , and 25 is a second wavelength converter. 26 is a control memory.

Wavelength-multiplexed optical signal of the wavelength lambda ₁ to [lambda] _n input highways are applied to the optical switch 22-1 to 22-n are demultiplexed into wavelength lambda ₁ to [lambda] _n corresponds by the demultiplexer 21. Each optical switch 22
-1 to 22-n can be combined with the total reflection type optical switch shown in FIG.
_By optimally designing for _{1 to} λ _n , an optical switch with low loss and high speed operation can be configured.

From each of the optical switches 22-1 to 22-n wavelengths lambda ₁ to [lambda] _n
Of the optical signal is output and added to the wavelength converters 24-1 to 24-n via the multiplexers 23-1 to 23-n. Each wavelength converter 24
-1 to 24-n have, for example, the configuration shown in FIG. Then, the optical signals of wavelengths λ _{1 to} λ _n are output from the wavelength converters 24-1 to 24-n, respectively, and are multiplexed by the multiplexer 25 to wavelength-multiplex the wavelengths λ ₁ to λ _{n on} the output highway. It is sent out as an optical signal.

For example, when replacing the input highways to the wavelength lambda _n of the output highways of the optical signal of the wavelength lambda _1, the optical signal of the demultiplexer 21 demultiplexes wavelength lambda _1, multiplexed by control of the optical switch 22-1 In addition to the multiplexer 23-n, an optical signal of wavelength λ ₁ is added from the multiplexer 23-n to the wavelength converter 24-n to output an optical signal of wavelength λ _n , which is multiplexed by the multiplexer 25. It will be.

〔The invention's effect〕

As described above, according to the present invention, the wavelength-multiplexed signals of the wavelengths λ _{1 to} λ _n of the input highway are demultiplexed by the demultiplexer and spatially connected and switched by the optical switch corresponding to the wavelength. A wavelength combiner combines and combines optical signals different from the wavelengths from each optical switch, a wavelength converter converts them to a predetermined wavelength, and a second multiplexer combines them to form a space division type optical switch. The constituent optical switches can be configured to have wavelength-corresponding characteristics, so that the switching of optical signals can be stabilized. Also, after the optical signals of different wavelengths from the respective optical switches are multiplexed by the first multiplexer, they are exchanged to the predetermined wavelengths by the wavelength converter, so that the optical signal of a certain wavelength on the input highway is changed to another one. There is an advantage that it is possible to economically provide a wavelength division type optical switching communication path which is converted into an optical signal having the wavelength of and is transmitted to the output highway as a wavelength multiplexed signal.

Also, since the electrical signal wiring length of the wavelength converter can be shortened,
The influence of band limitation due to stray capacitance can be reduced, and high-speed optical signal exchange can be performed by making the best use of the broadband property of light.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of a wavelength converter of an embodiment of the present invention, FIG. 3 is an explanatory diagram of an optical switch, and FIG. 4 is another of the present invention. FIG. 5 is a block diagram of an embodiment, FIG. 5 is a block diagram of a conventional example, and FIG. 6 is a block diagram of a wavelength converter of a conventional example. λ _{1 to} λ _n are wavelengths of optical signals, 1 is a demultiplexer, 2 is a space division type optical switch, 3 is a wavelength converter, 4 is a multiplexer, 5 is a control memory, 21 is a demultiplexer, 21- 1 to 22-n are optical switches, 23
-1 to 23-n are multiplexers, 24-1 to 14-n are wavelength converters,
Reference numeral 25 is a multiplexer, and 26 is a control memory.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-61-67388 (JP, A) JP-A-60-172841 (JP, A) JP-A-58-161489 (JP, A)

Claims (1)

[Claims] 1. A demultiplexer for demultiplexing a wavelength-multiplexed optical signal from an input highway corresponding to a wavelength, and a wavelength-dependent demultiplexer for spatially connecting and switching the optical signals demultiplexed by the demultiplexer and outputting the signals. A space division type optical switch composed of an optical switch, a first multiplexer for combining and multiplexing optical signals of different wavelengths from the wavelength compatible optical switch, and a multiplexer by the first multiplexer. A wavelength converter that converts the optical signals into optical signals of different predetermined wavelengths, and a wavelength converter that multiplexes the optical signals of different wavelengths from the wavelength converter and outputs a wavelength-multiplexed optical signal to the output highway
Wavelength division type communication path, which is equipped with a multiplexer.