JP2660210B2 - Wavelength division optical switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in the field of information and communication, in particular, in a switch for distribution service of high-speed signals such as high-definition images. The present invention relates to a wavelength division optical switch that is small in size and capable of switching high-speed signals with a large capacity. [Prior Art] The configuration of a conventionally proposed wavelength division optical switch is changed to the fifth.
Shown in the figure (Nishio, Suzuki et al. "Basic experiment of wavelength division optical switching")
(Refer to IEICE National Convention, 1842, 1843). The signals of the input signal lines 1-1 to 1-n of the channels 1 to n are respectively changed by the electro-optical conversion elements 2-1 to 2-n.
The light is converted into an optical signal having a wavelength (λ _{1 to} λ _n ). Each optical signal is transmitted by the input optical highways 3-1 to 3-n, multiplexed by the star coupler 4, and branched into n. The branched optical signals are transmitted by the output optical highways 5-1 to 5-n. An arbitrary wavelength is selected and output from each of the output optical highways 5-1 to 5-n using the variable wavelength filters 6-1 to 6-n. The optical signals of the selected wavelengths are converted into electrical signals by the optical-electrical conversion elements 7-1 to 7-n, respectively, and the output signal lines 8- of the channels 1 to n, respectively.
1 to 8-n. As described above, non-blocking
n wavelength division optical switches can be realized. Here, as the variable wavelength filter used in the conventional example, for example, as shown in FIG. 6, there is a wavelength filter of a λ / 4 shift structure DFB laser. That is, DF with λ / 4 shift structure
B laser has the feature that, when the injection current is set to an appropriate value below the oscillation threshold and light of multiple wavelengths is input, only a specific wavelength corresponding to the injection current value is amplified and output.
It can be used as a variable wavelength filter. As another variable wavelength filter, for example, as shown in FIG. 7, there is a wavelength filter of an acousto-optic device. That is, in the acousto-optic element, input light parallel to the wavelength λ with respect to the drive frequency f is θ _i = f · λ _i / v (i = 1 to n) (1) (θ: diffraction angle, f: acousto-optic It is diffracted in the direction of the driving frequency of the element, λ: wavelength of the input signal light, v: sound speed of the acousto-optic medium. However, as shown in FIG. 8, by selecting an appropriate frequency for the input light of wavelengths λ _{1 to} λ _n , light of any wavelength can be input to the optical-electrical conversion element 7 and used as a variable wavelength filter. it can. [Problems to be Solved by the Invention] In the conventional wavelength division optical switch described above, since the number of components is proportional to the number n of channels, for example, the space division type optical switch using a matrix in which the number of components is proportional to n ² is used. Compared with this, the amount of hardware can be significantly reduced. Another advantage is that high-speed signals can be handled. However, this switch has the disadvantage that the number n of channels is limited by the number of available wavelengths. In order to increase the capacity on the premise of non-blocking, a method of connecting the aforementioned wavelength division optical switches in a matrix as shown in FIG. 8 has been considered. According to this method, k · n channels can be realized using k ² wavelength division optical switches. However, in this case, since the amount of hardware is proportional to k ² , there is a disadvantage that the size of the apparatus becomes considerably large. An object of the present invention is to provide a wavelength division optical switch capable of handling a high-speed signal with a large capacity while maintaining the advantage of a wavelength division optical switch that requires a small amount of hardware by eliminating the above-mentioned disadvantages. [Means for Solving the Problems] In the present invention, channel 1 to channel (n is a natural number)
N input signal lines for transmitting the respective electrical input signals, and converting the input signals into optical signals having different wavelengths, performing predetermined multiplexing and branching, and converting them into n-channel electrical output signals. In a wavelength division optical switch including conversion means for outputting and n output signal lines each transmitting the output signal, the conversion means converts an input signal from the input signal line into k channels (k is a natural number). M multiplexers each outputting a time-division multiplexed multiplexed signal, m input highways each transmitting the multiplexed signal, and optical signals of m types of wavelengths each of the multiplexed signals on each input highway being different. M electrical-optical conversion elements for converting and outputting signals, m input optical highways for transmitting the optical signals, and one optical multiplexing optical signal on each input optical highway , A single output optical highway for transmitting the optical signal multiplexed by the multiplexer, an optical highway on the output optical highway, and arbitrary n wavelengths from the optical signal of the output optical highway. One multi-channel variable wavelength filter for selectively outputting an optical signal (which may be overlapped), and n for converting each of the n optical signals output from the multi-channel variable wavelength filter into an electrical output signal.
Optical-to-electrical conversion elements, n output highways transmitting output signals output from the respective optical-electrical conversion elements, and k-channel output signals time-division multiplexed on each output highway. And n time-division selectors for selecting one of the channels, converting the speed to a low speed, and outputting the converted signal to the output signal line, respectively. [Operation] The n-channel electrical input signals of channel 1 to channel n are time-division multiplexed by k channels by m multiplexers, and are converted into m multiplexed signals, and then converted into optical signals. The wavelength division processing is performed by the channel variable wavelength filter, the signal is again converted into an electrical multiplexed signal, and the original input signal is extracted from the multiplexed signal by the time division selector and output to the output signal line as an output signal. Therefore, the wavelength division processing conventionally performed for each channel can be collectively performed for each k channels, and the required hardware amount can be greatly reduced. Only one multi-channel tunable wavelength filter is required, and the amount of hardware can be further reduced. Embodiment An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.
1 shows an n-channel wavelength division optical switch. In this embodiment,
N input signal lines 1-1 to 1 for transmitting electrical input signals of channels 1 to n (n is a natural number)
1-n and m (m = n / k) output multiplexed signals obtained by time-division multiplexing input signals from the input signal lines 1-1 to 1-n by k channels (k is a natural number). Multiplexors 9-1 to 9-m, m input highways 10-1 to 10-m for transmitting the multiplexed signals, and multiplexed signals on the input highways 10-1 to 10-m, respectively. M electro-optical conversion elements 2-1 to 2-m for converting and outputting optical signals of different m wavelengths (λ _{1 to} λ _m ), and m input optical highways 3 for transmitting the optical signals of the m wavelengths -1 to 3-m
And one multiplexer 12 for multiplexing the optical signals of m wavelengths on each of the input optical highways 3-1 to 3-m, and one multiplexer for transmitting the optical signal multiplexed by the multiplexer 12. Output optical highway 5
One multi-channel tunable wavelength filter 14 for selecting and outputting an arbitrary n-wavelength optical signal (which may be overlapped) from the m-wavelength optical signal on the output optical highway 5; N optical-to-electrical conversion elements 7-1 to 7-n for converting the n optical signals output from the wavelength filter 14 into electrical output signals, respectively, and each optical-to-electrical conversion element 7-1
N for transmitting the output signals output from .about.7-n, respectively.
Only the output highways 11-1 to 11-n and the channels among the k-channel output signals time-division multiplexed on the output highways 11-1 to 11-n are selected and speed-converted to a low speed. Time-division selectors 13-1 to 13-n for respectively outputting the output signals, and time-division selectors 13-1 to 13-n
And n output signal lines 8-1 to 8-n for transmitting the output signals from -n, respectively. The feature of the present invention is that the multiple
-1 to 9-m, a multiplexer 12, a multi-channel variable wavelength filter 14, and time-division selectors 13-1 to 13-n. Next, the operation of the present embodiment will be described. The n-channel electrical input signals transmitted by the n input signal lines 1-1 to 1-n are converted into m k: 1 multiplexers 9-1 to 9-1.
9-m (m = n / k) to perform time division multiplexing and output to m input highways 10-1 to 10-m. Each transmitted signal to the m respective electricity through the input highway 10-1 to 10-m - converted into an optical signal of the m wavelengths lambda ₁ to [lambda] _m by the optical conversion element 2-1 to 2-m, Output to the input optical highways 3-1 to 3-m. Each input optical highway 3
After the optical signals of −1 to 3-m are multiplexed by the multiplexer 12,
The light is output to the output light highway 5. The optical signal on the output optical highway 5 is input to a multi-channel tunable wavelength filter 14, and the multi-channel tunable wavelength filter 14 outputs light of an arbitrary wavelength to n light-to-electric conversion elements 7-1 to 7-n. And convert them into electrical output signals, respectively,
It outputs to the output highways 11-1 to 11-n. Further, one of the k output signals time-division multiplexed on the output highways 11-1 to 11-n is selected by the n time division selectors 13-1 to 13-n. The speed is converted as shown in (1) and output to the output signal lines 8-1 to 8-n, respectively. By selecting a wavelength to be selected by the multi-channel variable wavelength filter 14 and a channel to be selected by the time division selectors 13-1 to 13-n, an arbitrary input channel of the input signal lines 1-1 to 1-n can be output to an arbitrary output signal. Lines 8-1 to 8-n
Can be connected non-blocking. The time-division selectors 13-1 to 13-n can be realized by, for example, a configuration as shown in FIG. That is, a shift register 21, a latch 22 for latching data by a frame pulse, and a selection signal for an i-th time slot.
And a selector 23 that operates at 24. The data input from the k time-division multiplexed output highways 11 is read into the shift register 21 and latched by a frame pulse.
And one of the data in the latch 22 is read out by the selector 23 by the selection signal 24, thereby realizing the function of the time division selector. Also, the multi-channel tunable wavelength filter 14 is
As shown in the figure, it is effective to drive the acousto-optic element at multiple frequencies (Shimadzu, Nishi, Yoshikai "Experimental study of wavelength division multiplexing optical switch using optical deflection element", Optical and Radio Division, IEICE, 1986) National Convention 288, see). That is, the acousto-optic element 31, the transducer 32, and the multi-coupler 33
And, k number of oscillator 34-1~34-k (frequency f _1, ..., f _k)
When, and a lens 35 and 36, the wavelength lambda ₁ from an input optical highway _3, lambda _2, ..., and the parallel light signal a light signal of lambda _m through the lens 35, is input to the acousto-optic element 31. Frequency f ₁ from the other oscillator _{34-1~34-k, f 2, ...} , superimposed by an electric signal multi-coupler 33 f _k, thereby driving the acousto-optic element 31. At this time, the optical signal of each wavelength is independently diffracted in the directions of θ _ij = f _i · λ _j / v (i = 1 to k, j = 1 to m) (2). But the frequency
By appropriately selecting f ₁ , f ₂ ,..., f _k, as shown in FIG. 4, an optical signal of an arbitrary wavelength is transmitted via a lens 36 to n optical-electrical conversion elements 7-1 to 7-. n. [Effects of the Invention] As described above, the present invention further provides time-division multiplexing of the signal sequence of each wavelength of the conventional wavelength division optical switch, so that wavelengths which have been limited by the number of wavelength The number of channels of the split optical switch can be greatly increased, and the amount of hardware is very small as compared with the conventional type. In addition, only one acousto-optic element is required, and the configuration is significantly simpler than the method using a plurality of acousto-optic elements. Therefore, according to the present invention, there is provided a wavelength division optical switch that is small, has a large capacity, can switch high-speed signals, and can have an arbitrary number of output signal lines by changing the number of branches of optical signals. This is particularly suitable for a switch for distributing services of high-speed signals such as high-quality moving images, and the effect is great.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG. 2 is an explanatory diagram showing details of the time division selector. FIG. 3 is an explanatory view showing details of the multi-channel variable wavelength filter. FIG. 4 is an explanatory view of the principle of a multi-channel variable wavelength filter. FIG. 5 is a block diagram showing a conventional example. FIG. 6 is an explanatory diagram of a conventional DFB laser variable wavelength filter. FIG. 7 is an explanatory diagram of a conventional acousto-optic tunable wavelength filter. FIG. 8 is an explanatory view of a conventional large capacity wavelength division optical switch. 1-1 to 1-n ... input signal lines, 2-1 to 2-m, n ...
... Electro-optical conversion element, 3, 3-1 to 3-m, n ... Input optical highway, 4 ... Star coupler, 5, 5-1 to 5-
n: output optical highway, 6-1 to 6-n: variable wavelength filter, 7, 7-1 to 7-n: optical-electrical conversion element,
8-1 to 8-n: output signal line, 9-1 to 9-m: multiplexer, 10-1 to 10-m: input highway, 1
1, 11-1 to 11-n ... output highway, 12 ... multiplexer, 13-1 to 13-n ... time division selector, 14 ... multi-channel variable wavelength filter, 21 ... shift register, 22 ......
Latch, 23 ... Selector, 24 ... Selection signal, 31 ... Acoustic-optical element, 32 ... Transducer, 33 ... Multi coupler, 34-1 to 34-k ... Oscillator.

Claims (1)

(57) [Claims] N input signal lines (1) for transmitting electrical input signals of channels 1 to n (n is a natural number)
Conversion means for converting the input signal into an optical signal having a different wavelength, performing predetermined multiplexing and branching, and converting and outputting the n-channel electrical output signal; and the output signal N output signal lines (8-1 to
8-n), wherein the conversion means outputs m multiplexed signals obtained by time-division multiplexing the input signal from the input signal line by k channels (k is a natural number). A multiplexer (9-1 to 9-m) and m input highways (10 to 10) each transmitting the multiplexed signal.
-1 to 10-m), and m for converting and outputting the multiplexed signal on each input highway into optical signals of m different wavelengths.
Electrical-optical conversion elements (2-1 to 2-m) and m input optical highways (3-1) for transmitting the optical signals, respectively.
... 3-m), one multiplexer (12) for multiplexing the optical signal on each input optical highway, and one output optical highway for transmitting the optical signal multiplexed by the multiplexer. (5) one multi-channel variable wavelength filter (14) for selecting and outputting an optical signal of arbitrary n wavelengths (which may be overlapped) from the optical signal on the output optical highway; N optical-electrical conversion elements (7-) for respectively converting the n optical signals output from the variable wavelength filter into electrical output signals.
1 to 7-n), n output highways for transmitting output signals output from the respective optical-electrical conversion elements, and k-channel output signals time-division multiplexed on each output highway. A wavelength division optical switch comprising: n time division selectors (13-1 to 13-n) for selecting a channel, converting the speed to a low speed, and outputting the converted signals to the output signal lines.