JP2816407B2 - Optical multiplexing circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a high-speed, large output optical power,
Also, the present invention relates to an optical multiplexing circuit for reducing the number of components.

[Conventional technology]

Conventionally, as shown in FIG. 4, there has been known an optical multiplexing circuit capable of multiplexing in word units (one word is k bits). In the figure, first, input data is converted into a bit rate v by n electrical input signal lines _1-1 to 1- _n.
[Bit / s]. On the other hand, the optical pulse oscillator 12
Outputs an ultrashort optical pulse having a pulse width t (where t≪1 / v) at a constant period k / v, which is output by the 1: n splitter 3.
The process branches n times. The optical multiplexing interface circuits 14 _{-1 to} 14 _-n respectively connected to the respective output terminals of the 1: n splitter 3 convert the optical pulse supplied from the optical pulse oscillator 12 into the input signal 1 _-1.
To 1 respectively modulated according _-n data, compresses the modulated optical pulse train the number of bits k, for each word of the bit interval t, and outputs the word in each cycle k / v. The output terminal of each of the multiplexing interface circuits 14 _{-1 to} 14 _-n has i · kt ·
n delay lines 5 _{-1 to} 5 _-n giving a delay of i = 1, 2,..., n)
Are connected to each other, so that the modulated optical pulse train of each word unit has a delay (it, 2 · it, 3 · i
,..., n · it), and then multiplexed by the n: 1 coupler 6 and transmitted from the output optical highway 7.

Here, the configuration of the optical multiplexing interface circuit 14 _-i (i = 1, 2,..., N) provided in the above-described conventional optical multiplexing circuit is shown in FIG. In this figure, first, the input signal line
K-bit input data D _{1 to} Dk supplied by 1 _-i
Is input to the shift register 15, and then k bits (1
Each word is input to the latch circuit 16. The pulse light having a pulse width of t and a period of k / v supplied from the optical pulse oscillator 2 via the 1: n splitter 3 is split by the 1: k splitter 17, and these split optical pulses are electrically the optical pulse modulator 18 _-1 to 18 using an optical effect _- is modulated in accordance with the output of the latch circuit 16 by k. Each of these optical pulse modulators 18 _-1 to
18 _- light pulse respectively modulated by k, the delay lines 19 _-1 to
Each delay time of i · t (i = 1, 2,..., N) is given by 19 ₋₁ k, and they are combined by a k: 1 combiner 20.

With the above configuration, the input data bit rate v supplied by the input signal line 1 _-1 to 1 _-n is modulated in parallel for each word of k bits by each optical multiplexer interface circuit 14 _-1 to 14 _-n After that, each word is multiplexed by the combiner 6 after being compressed, and the multiplexed modulated optical pulse train obtained by this is output with a period k / v.

[Problems to be solved by the invention]

By the way, in the above-mentioned conventional optical multiplexing circuit,
Since an ultrashort light pulse having a pulse width t is used, the multiplex number n =
There is an advantage that 1 / (tv) can be increased. However, the optical multiplexing interface circuits 14 _-1 to 14 _-1
14 light pulses in _-n 1: To k branch, has the disadvantage of not enough light power can be obtained and the respective optical multiplexing interface circuit 14 every _-1 to 14 _-n, k-number of light pulses modulator 18 _-1 to 18 _- and k, k the delay line 19 _-1 to 19 _- for k are needed, there is a disadvantage that the construction is complicated.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide an optical multiplexing circuit which improves a conventional optical multiplexing circuit, obtains a large output optical power, and requires a small number of components.

[Means for solving the problem]

According to the present invention, n input signal lines for input data to be supplied at a bit rate v and a pulse width t (where t≪1 / 1 /
v) an optical pulse oscillator that outputs an ultrashort optical pulse at a constant period 1 / v, a branching device that branches the optical pulse output from the optical pulse oscillator into n, and an optical pulse that is branched by the branching device. N optical multiplexing interface circuits each of which modulates according to the data of each input signal line and compresses and outputs the resulting modulated optical pulse train for each k-bit word; Output each i
· N delay lines for providing a delay of k · t (i = 1, 2,..., N), and a coupler for coupling the outputs of the respective delay lines;
An output optical highway for transmitting the output of the coupler, and modulating each of the optical multiplexing interface circuits in series with the optical pulses output from the splitter based on the data of each of the input signal lines. An optical pulse modulator, a 1 × 2 optical switch that outputs an optical pulse train sequentially output from the optical pulse modulator from a first output terminal, and (1 / v) − a first output of the optical switch. an internal delay line that gives a delay of t, and an internal coupler that feeds back the output of the internal delay line to the input terminal of the optical switch, and switches the optical switch for a constant period at a constant period k / v. And outputting a compressed modulated optical pulse train for each k-bit word from a second output terminal of the optical switch.

[Action]

According to the above configuration, the oscillation cycle of the optical pulse oscillator is set to 1 /
The output light power can be increased by k times by increasing the speed to k times that of the conventional one, and further, as in the conventional optical multiplexing interface circuit, the ultrashort optical pulse is branched by 1: k and k bits are output. Instead of modulating each time in parallel, the light pulse is k times faster and serially modulated, so the components of the optical multiplexing interface circuit can be reduced to 1 / k or less, especially The optical multiplexing interface circuit occupies a major part of the optical multiplexing circuit, and the effect of reducing the number of components is great.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the configuration of one embodiment of the present invention.
In this figure, 1 _-1 to 1 _-n electrical input signal line, 2 pulse width t (where, t«1 / v) optical pulse oscillator for outputting ultrashort optical pulses of a constant period 1 / v 3, 1: n switch, 4 _-1
4 _-n are optical multiplexing interface circuits, 5 _{-1 to} 5 _-n are delay lines with delay times i · kt (where i = 1, 2,..., N), and 6 is n: 1 The coupler 7 is an output optical highway.

In such an optical multiplexing circuit, n input signal lines
According to 1 ₋₁ to 1 _−n , the input data has a bit rate v [bit /
s]. On the other hand, an ultrashort optical pulse having a pulse width t (where t≪1 / v) is output from the optical pulse oscillator 2 at a constant period of 1 / v. The optical multiplexing interface circuits _4-1 to 4- _n connected to the respective output terminals of the 1: n splitter 3 convert the optical pulses supplied from the optical pulse oscillator 2 into the input signal lines _1-1 to 1-1. respectively modulated according to data _-n, compresses the modulated optical pulse train the number of bits k, for each word of the bit interval t, and outputs the word in each cycle k / v. Each multiplex interface circuit 4
The output terminals of _-1 to 4- _n have i · kt · (where i = 1, 2,...)
.., N) are connected to the _n delay lines 5 _{-1 to} 5 _-n, and the delay (it, 2 · it, 3 ・ it, ……, n ・ i
t) are each given and then multiplexed by the n: 1 combiner 6 and sent out by the output optical highway 7.

Next, the configuration of the optical multiplexing interface circuit 4- _i (i = 1, 2,..., N) provided in the optical multiplexing circuit according to the present embodiment will be described with reference to FIG. In this figure, 8 is an optical pulse modulator using the electro-optic effect, 9 is a 1 × 2 optical switch having one input and two outputs, 10 is a delay line for giving a delay time (1 / v) −t, and 11 is two inputs. This is a 1 × 2 × 1 coupler.

In such an optical multiplexer interface circuit 4 _-i, it is first supplied input data D ₁ to Dk of k bits by the input signal line 1 _-i sequentially, and at the same time, output from the optical pulse oscillator 2 pulse width An ultrashort optical pulse having a period of 1 / v at t is supplied to the optical pulse modulator 8 via the 1: n splitter 3. Then, the optical pulse modulator 8 sequentially modulates the supplied optical pulses in accordance with the data on the input signal line 1-i. Next, the modulated optical pulse train P ₁ is a 2 × 1 coupler
It is supplied to the 1 × 2 optical switch 9 via 11. This 1 ×
The two-optical switch 9 always outputs the optical pulse supplied to the input terminal from the delay line 10 side (first output terminal), and the supplied optical pulse is supplied during the period in which the gate pulse (electric signal) Gp is supplied. The optical pulse is output from the output port side (second output terminal). The delay line 10 of this 1 × 2 optical switch 9
After the optical pulse output from the side goes around the delay line 10,
× is multiplexed with subsequent optical pulses through one coupler 11, as the optical pulse train P _2, is fed back to the input side of the 1 × 2 optical switch 9. Such a feedback operation is repeated k times, and an optical pulse train of k bits at a bit interval t is 2
× when it is generated by a coupler 11, 1 × respect 2 optical switch 9, a gate pulse Gp for a fixed period k / v are supplied, one word optical pulse train P ₃ are 1 × 2 of (k bits) Output from the output port side of the optical switch 9. Here, for example, the operation of each unit when the number of bits is k = 8 is as shown in FIG. The modulation signals are all set to 1 for simplification.

With the above configuration, the input data of the bit rate v supplied by the input signal lines _1-1 to 1- _n are serially output for each k-bit word by each of the optical multiplexing interface circuits _4-1 to 4- _n . After being modulated, it is compressed, and each word is multiplexed by the combiner 6, and the multiplexed modulated optical pulse train obtained by this is output with a period k / v.

〔The invention's effect〕

As described above, according to the present invention, the output optical power can be increased by k times by setting the oscillation period of the optical pulse oscillator to 1 / v and increasing the speed to k times the conventional value. As in the case of an optical multiplex interface circuit, instead of splitting an ultrashort optical pulse by 1: k and modulating in parallel every k bits, the optical pulse is speeded up by k times and serially modulated. The number of optical pulse modulators and delay lines, which were components of the optical multiplexing interface circuit, can be reduced to 1 / k, and shift registers and latch circuits can be omitted. For example, octet multiplexing (k = 8), the present invention has the effect of increasing the output optical power by a factor of eight and further reducing the number of components of the optical multiplexing interface circuit to 1/8 or less.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical multiplexing circuit according to one embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of an optical multiplexing interface circuit of the optical multiplexing circuit according to the embodiment, and FIG. FIG. 4 is a timing chart for explaining the operation of each part of the embodiment, FIG. 4 is a block diagram showing the configuration of a conventional optical multiplexing circuit, and FIG. 5 is a block diagram of an optical multiplexing interface circuit of the conventional optical multiplexing circuit. FIG. 3 is a block diagram illustrating a configuration. 1 _-1 to 1 _-n ...... input signal line, 2 ...... light pulse oscillator, 3 ...... 1: n splitter, 4 _-1 to 4 _-n ...... light multiplexing interface circuit, 5 _-1 5 _{- n} : delay line, 6: n: 1 coupler, 7: output optical highway, 8: optical pulse modulator, 9: 1 × 2 optical switch, 10: delay line (internal delay line), 11 ... 2x1 coupler (internal coupler).

Claims (1)

(57) [Claims] An input signal line to which input data is supplied at a bit rate v, a pulse width t (where t≪1 / 1 /
v) an optical pulse oscillator that outputs an ultrashort optical pulse at a constant period 1 / v, a branching device that branches the optical pulse output from the optical pulse oscillator into n, and an optical pulse that is branched by the branching device. N optical multiplexing interface circuits each of which modulates according to the data of each input signal line, and reduces and outputs the resulting modulated optical pulse train for each k-bit word; Output each i
· N delay lines for providing a delay of k · t (i = 1, 2,..., N), and a coupler for coupling the outputs of the respective delay lines;
An output optical highway for transmitting the output of the coupler, wherein each of the optical multiplexing interface circuits sequentially modulates an optical pulse output from the splitter based on data of each of the input signal lines. An optical pulse modulator, a 1 × 2 optical switch that outputs an optical pulse train sequentially output from the optical pulse modulator from a first output terminal, and an output of a first output terminal of the optical switch. v) An internal delay line for giving a delay of -t, and an internal coupler for feeding back the output of the internal delay line to the input terminal of the optical switch, wherein the optical switch is fixed at a constant period k / v. An optical multiplexing circuit, wherein a period of time is switched and a compressed modulated optical pulse train is output from a second output terminal of the optical switch for each k-bit word.