JPH03255736A - Optical signal processing circuit - Google Patents

Abstract

PURPOSE:To process high-speed optical signals by providing a light extracting means, a photoelectric converting means, a mean value calculating means, a variable frequency oscillating means and electrooptical converting means. CONSTITUTION:A light extracting means 10 separates and extracts the low-speed optical signal from the high-speed optical signal according to a repeated light sampling signal. The photoelectric converting means 20 converts the low-speed optical signal extracted by the light extracting means 10 to a low-speed electric signal, and an mean value calculating means 22 calculates the mean value of this low-speed electric signal. A variable frequency oscillating means 24 generates a signal with a frequency to be changed corresponding to the output of the mean value calculating means 22, and an electrooptical converting means 26 exerts electrooptical conversion upon the output of the variable frequency oscillating means 24 and defines the converted output as the repeated light sampling signal. An identifying means 28 defines the output of the variable frequency oscillating means 24 as an identification signal and extracts the signal by identifying the low-speed electric signal based on this timing. Thus, the reception demodulation processing of the high-speed optical signal, which can not be processed by being directly converted to the electric signal, can be executed.

Description

[Detailed Description of the Invention] [Summary] This invention relates to an optical signal processing circuit that separates and extracts optical signals at the optical level and converts them into electrical signals, and is capable of processing high-speed optical signals that are difficult to directly convert into electrical signals. The purpose of the present invention is to propose an optical signal processing circuit for separating and extracting signals from a high-speed optical signal consisting of a return-to-zero signal. an extraction means, a photoelectric conversion means for converting the low-speed optical signal into a low-speed electric signal, an average value calculation means for calculating an average value of the low-speed electric signal, and a frequency that changes according to the output of the average value calculation means. variable frequency oscillation means for generating an electrical signal, and an output of the variable frequency oscillation means is subjected to electro-optical conversion to produce the repetitive optical sampling signal. The apparatus includes an electro-optical conversion means, and an identification means for extracting a signal by using the output of the variable frequency oscillation means as an identification signal and identifying the low-speed electrical signal based on the timing of the identification signal.

[Industrial application field]

The present invention generally relates to an optical signal processing circuit that separates and extracts an optical signal at the optical level and converts it into an electrical signal, and in particular, relates to an optical signal processing circuit that synchronously separates and extracts an optical signal at the optical level and converts it into an electrical signal. This invention relates to an optical signal processing circuit.

Optical communication is currently being actively used, but its bit rate is increasing year by year, and it is expected that the demand for even higher speeds will increase in the future. The present invention refers to an optical signal processing circuit to meet such needs.

[Conventional technology]

In conventional optical communication systems, a desired electrical signal is obtained by directly converting the transmitted optical signal into an electrical signal using a photoelectric conversion element.

However, as mentioned above, the bit rate of optical communication systems has been increasing, and this trend is on the rise. Considering this situation, in the conventional method, demands for higher speeds in the electro-optic converter and the opto-electric converter become increasingly severe. In the current electro-optical converter, when the light source is a semiconductor laser, the speed is 16 Gb/s using direct modulation method, and 20 Gb/s using modulation method that combines phase modulation and interferometer.
The value of is obtained. However, even the fastest optical receiving circuit is 16 Gb/s, and 20 Gb/s has not been realized. In this way, the reception method becomes more difficult as the bit rate increases.

Therefore, as a solution to this problem, a method has been considered in which the high-speed optical signal is processed at the optical level, a part of which is separated as a low-speed optical signal, and converted into an electrical signal for subsequent processing (for example, Peter pi.

Sm1th, “On the Role of Ph
otonic Switching 1nFuture
(See Communications System)
Some optical devices have also been proposed that can be used for this purpose.

[Problem to be Solved by the Invention] In this case, the problem is how to implement an optical signal processing circuit that implements such processing.

Furthermore, the above-mentioned high-speed optical signals are generally time-division multiplexed, that is, bit or byte multiplexed signals in many cases. Therefore, it is necessary to find a structure for realizing an optical signal processing circuit capable of separating and extracting each signal by separating multiplexed high-speed optical signals at the optical level.

Therefore, the first object of the present invention is to separate a signal at the optical level from a high-speed optical signal modulated with a signal of such a high bit rate that it is impossible at present or in the future to directly convert it into an electrical signal. The object of the present invention is to propose the configuration of an optical signal processing circuit that extracts the signal and then converts it into an electrical signal for subsequent processing.

A second object of the present invention is to propose a configuration of an optical signal processing circuit that can obtain each signal by separating bit- or byte-multiplexed high-speed optical signals at the optical level.

[A means of promise to solve problems]

FIG. 1 is a diagram showing the basic configuration of an optical signal processing circuit according to the present invention that solves the first object mentioned above. The optical signal processing circuit of the present invention is an optical signal processing circuit that separates and extracts signals from a high-speed optical signal consisting of a return-to-zero signal.
, photoelectric conversion means 20 , average value calculation means 22 , variable frequency oscillation means 24 , electro-optical conversion means 26 , and identification means 28 .

The optical extraction means 10 separates and extracts the low-speed optical signal from the high-speed optical signal based on the repetitive optical sampling signal.

The photoelectric conversion means 20 converts the low-speed optical signal extracted by the light extraction means 10 into a low-speed electric signal. The average value calculation means 22 calculates the average value of this low-speed electric signal. The variable frequency oscillation means 24 generates a signal whose frequency changes according to the output of the average value calculation means 22. The electro-optic conversion means 26 converts the output of the variable frequency oscillation means 24 into an electro-optical signal to form the above-mentioned repetitive optical sampling signal.

The identification means 28 uses the output of the variable frequency oscillation means 24 as an identification signal, and extracts the signal by identifying the low-speed electrical signal based on this timing.

FIG. 2 is a diagram showing the configuration of an optical signal processing circuit according to the present invention that solves the second object mentioned above. In FIG. 2, the optical signal processing circuit of the present invention is an optical signal processing circuit that separates and extracts each signal from a high-speed optical signal consisting of a bit or byte multiplexed return-to-zero signal, and includes a branching means 30, a plurality of a light extraction means 10.10', a plurality of opto-electric conversion means 20.20', an average value calculation means 22, a variable frequency oscillation means 24, an electro-optic conversion means 26, and a plurality of identification means 28.28. ', optical delay means 32, and electrical delay means 3
4.

The branching means 30 branches the high-speed optical signal into a plurality of high-speed optical signals and supplies each of them to the plurality of light extraction means 10.about.10'. The plurality of optical extraction means 10.10' separate and extract low-speed optical signals from the plurality of high-speed optical signals using repetitive optical sampling signals. A plurality of electro-optical conversion means 20.2
0' converts each low-speed optical signal into a low-speed electrical signal.

The average value calculation means 22 calculates the average value of the output of one photoelectric conversion means 20. The variable frequency oscillation means 24 generates an electrical signal whose frequency changes according to the output of the average value calculation means 22. The electro-optical conversion means 26 is an optical extraction means that converts the output of the variable frequency generation means 24 into electro-optical signals and supplies an optical sampling signal of the same system, that is, a low-speed optical signal to the above-mentioned one opto-electric conversion means 20. 10 as a repetitive optical sampling signal to the optical extraction means 10. The plurality of identification means 28 and 28' each identify the low-speed optical signal based on the timing of the identification signal.
One identification means 28 which extracts each signal and is supplied with a low-speed electrical signal from the one opto-electrical conversion means 20 mentioned above.
The identification signal is the output of the variable frequency oscillation means 24. The optical delay means 32 applies different delays to the outputs of the electro-optical conversion means 26 and supplies them to the other optical extraction means 10' as repetitive optical sampling signals. The electrical delay means 34 applies different delays to the outputs of the variable frequency oscillation means 24, and supplies them to the other identification means 28' as identification signals.

[For production]

In the configuration shown in FIG. 1, if the high-speed optical signal input to the light extraction means 10 is a return-to-zero (RZ) signal, the light extraction means 10 performs the signal extraction function, as will be described in detail in later embodiments. In addition, it also functions as a phase comparison circuit.

Therefore, by converting this signal into an electrical signal in the photoelectric conversion means 20 and calculating the average value in the average value calculation means 22, a signal corresponding to the phase difference between the high speed optical signal and the optical sampling signal can be obtained. Furthermore, if a signal whose frequency changes according to this signal is electro-optically converted and supplied to the light extraction means 10 as an optical sampling signal, a phase comparison loop (PL
L) is formed, and the output of the variable frequency oscillation means 24 becomes a signal phase-synchronized with the high-speed optical signal, allowing the identification means 28 to identify the signal.

In the configuration shown in FIG. 2, a light extraction means 10, a photoelectric conversion means 20, an average value calculation means 22, and a variable frequency oscillation means 24
, and the electro-optical conversion means 26 is the first loop.
It has the same configuration as the phase-locked loop explained in the figure and exhibits the same effect. Therefore, one of the multiplexed signals is separated in the light extraction means 10 and identified by the identification means 28.

Regarding other signals, the optical delay means 32 provides optical sampling signals of each system, and the electrical delay means 34 provides identification signals.

〔Example〕

FIG. 3 is a diagram showing a first embodiment of the optical signal processing circuit according to the present invention.

The light combined with the optical sampling signal at the optical coupler 102 is input to the bistable laser diode 100, and the output light is converted into an electrical signal at the opto-electric conversion element 200, and unnecessary high-frequency components are removed at the equalization amplifier 202. The signal is amplified and input to the identification and reproducing circuit 280. The output of equalizing amplifier 202 is also input to low pass filter 220, the output of which becomes the control voltage for voltage controlled oscillator 240. The output signal of the voltage controlled oscillator 240 is transmitted to the identification reproducing circuit 2.
80 as a clock for identification and reproduction, and is converted into an optical signal by electro-optical conversion element 260 to become an optical sampling signal, which is input to one entrance of optical coupler 102. The electro-optical conversion element 260 outputs a short width optical pulse at the rising edge of an input electrical signal.

As shown in column (A) of FIG. 4, the bistable laser diode 100 has a hysteresis characteristic in its optical output with respect to the injected current. Here, when the injection current is set to the value shown by b, the characteristics of the output light with respect to the input light exhibit similar hysteresis characteristics as shown in column (B). Therefore, when the injected current is set to the value already shown in column (A), the optical output is essentially zero while the optical input is smaller than the value shown by p and is located outside the hysteresis loop. , p
When the value is larger than the value indicated by and is located outside the hysteresis loop, it becomes an approximately constant value. Therefore, when the intensity of the optical sampling signal is combined with the optical sampling signal when the level of the high-speed optical signal is logic "1", the intensity is p
The optical sampling signal is set so that when it is a value outside the hysteresis loop that is larger than p and is logic "0", the intensity when combined with the optical sampling signal is a value outside the hysteresis loop that is smaller than p. By setting the high-speed optical signal to be a value outside the hysteresis loop that is smaller than p, no matter what value the high-speed optical signal has, a part of the high-speed optical signal can be separated and extracted using an optical sampling signal as described later. It becomes possible to do so.

FIG. 5 is a flowchart for explaining the operation of the circuit of FIG. 3 under such conditions.

Figure 5 (A
) to (E) columns. - As an example, the intensity of the optical sampling signal in column (B) is approximately 2 of the intensity of the high-speed optical signal in column (B).
The period is set to 6 times. For example, if a high-speed optical signal is input in the form shown in column (A), the output of the optical coupler 102 will be in the form shown in column (C), which is input to the bistable laser diode 100. The bistable laser diode 100 is continuously injected with a current of the value already shown in column (A) of FIG.
) in the position indicated in the column. Therefore, the output of the bistable laser diode 100 is as shown in column (D),
A part of the high-speed optical signal is separated and extracted using an optical sampling signal. As will be detailed later, the optical separation circuit formed by the optical coupler 102 and the bistable laser diode 100 also has the function of a phase comparator, and forms a phase-locked loop with the low-pass filter 220 and the voltage-controlled oscillator 240. As a result, the phase of the optical sampling signal (column (B)), that is, the phase of the output of the voltage controlled oscillator (column (E)), is synchronized with the high-speed optical signal, and this signal is used as a clock to be separated in the identification and regeneration circuit 280. Identification and reproduction of the signal is performed.

6 and 7 are diagrams for explaining the function of the optical separation circuit using the optical coupler and the bistable laser diode 100 as a phase comparator and the principle of phase synchronization thereby. In Figure 6, when the high-speed optical signal (column (A)) and the optical sampling signal match in phase (column (B,))
, the output is as shown in (column (D)), and the widest pulse is output.

When the phase shifts by 90° (column (B2) or column (B3)), the width becomes narrower (column (D2) or (D3))
, when deviated by 180° (column (B, ) or column (B5))
, the width is zero ((D,) column or (D5) column). Therefore, if a code is used that makes the average value constant, as shown in FIG. 7, the average value of the output of the separation circuit, that is, the output voltage of the low-pass filter 220 (FIG. This corresponds to the phase difference between the optical signal and the optical sampling signal. Any point on the diagonal line in Figure 7 may be used, but for example, if the control point is set at position They match and become completely phase synchronized.

FIG. 8 is a diagram showing a second embodiment of the present invention. Third
The main difference from the circuit shown in the figure is that the current flowing into the bistable laser diode 100 is not constant, but is controlled by the output of the voltage controlled oscillator 240. Further, the value of the injection current when the output of the voltage controlled oscillator 240 is logic "1" is set to the value indicated by c instead of the value already indicated in the column (A) of FIG. When the injection current is a value C, a bistable laser diode exhibits an irreversible threshold characteristic as shown in column (C) of FIG. 4. In other words, as the optical input increases, q
The optical output is almost zero up to the value indicated by , but increases rapidly beyond this value, and even if the optical input is then returned to zero, the optical output does not become zero. In order to return the optical output to zero, it is necessary to reduce the injected current to zero. This is accomplished by configuring the injection current to be zero when the voltage controlled oscillator 240 output is a logic "0".

FIG. 9 is a diagram explaining the operation of the circuit of FIG. 8. Fifth
The operation is almost the same as that explained in the figure, but the output of the laser diode 100 (column (D)) is turned on when the value of the input (column (C)) exceeds the value indicated by q, and - the output of the voltage controlled oscillator is turned on. It turns off when the output (column (E)) falls. With this configuration, compared to the embodiment shown in FIG.
A wide light pulse is obtained and stable photoelectric conversion is achieved.

FIG. 10 is a diagram showing a third embodiment of the optical signal processing circuit according to the present invention. The main difference from the circuit of FIG. 3 is that an optical gate element 110 is used instead of the bistable laser diode 100. The optical gate element 110 transmits and outputs the signal light when control light of a predetermined wavelength different from the signal light of a predetermined wavelength is input, and absorbs the signal light due to the Franz Kjelditssch effect when no control light is input. (Wakao et al., 1989 Institute of Electronics, Information and Communication Engineers Autumn National Conference Lecture Proceedings C-185). Therefore, optical separation is achieved by matching the wavelength of the high-speed optical signal with the wavelength of the signal light of the optical gate element 110 and matching the wavelength of the optical sampling signal with the wavelength of the control light of the optical gate element 110.

FIG. 11 is a timing chart for explaining the operation of the circuit shown in FIG. 10. The diagonal line downward to the left represents a high-speed optical signal having a wavelength equal to the wavelength of the signal light of the optical gate element 110, and the diagonal line downward to the right represents an optical sampling signal having a wavelength equal to the wavelength of the control light of the optical gate element 110.

An optical signal is output to the output of the optical gate element 110 (column D) only when signal light and control light are input simultaneously, and the optical separation function is achieved.

FIG. 12 is a diagram showing a fourth embodiment of the optical signal processing circuit according to the present invention. The difference from the circuit shown in FIG. 3 is that a series connection of an optical wavelength conversion laser 120 and a selective transmission filter 122 is used instead of the bistable laser diode 100.

FIG. 13 is a diagram for explaining the characteristics of this optical wavelength conversion laser 120. An optical wavelength conversion laser converts a predetermined wavelength (
When light of wavelength λ1 is input, it outputs light of a different wavelength (lambda 2) from the input light, but for low-level optical input, it outputs light whose wavelength has been converted (referred to as (shown by the solid line in the figure), but has the characteristic of outputting only amplified light (shown by the broken line) in response to high-level optical input (Nobuhara et al., 36th Applied Physics Association Lecture Lecture proceedings volume 3 2P-2C-15). Focusing only on the light with wavelength λ1 out of the output light, when the level of the input light with wavelength λ1 exceeds a predetermined value (indicated by T), light with wavelength λ1 is output, and the selective transmission filter 122 reduces the wavelength λ1. If only the signals of , , and , are allowed to pass through, the same operation as that explained in FIG. 5 can be achieved.

FIG. 14 is a timing chart illustrating the operation of the circuit shown in FIG. 12. It is the same as FIG. 5 except that the darkness value is γ.

FIG. 15 is a diagram showing a fifth embodiment of the present invention. A nonlinear optical element 130 having a quantum well (MQW) structure is used as a light separation element, and other than that, the structure is similar to the other embodiments described so far.

A nonlinear optical element having a quantum well structure has the property that its absorption spectrum shifts when light of a specific wavelength is input (for example, Peter W, Sm1th).

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Switching in FutureCommun
cations System). therefore,
Set the wavelength of the optical sampling signal to this specific wavelength,
If the wavelength of the high-speed optical signal is set to a wavelength at which the absorption spectrum shifts and the amount of absorption decreases when this specific wavelength is input, it will be similar to the optical gate element 110 explained in FIGS. 10 and 11. You can perform various actions.

FIG. 16 is a timing chart for explaining the operation of the circuit shown in FIG. 15, and is similar to FIG. 11.

FIG. 17 is a diagram showing a sixth embodiment of the optical signal processing circuit according to the present invention. The circuit shown in the figure is a circuit for separating a high-speed optical signal consisting of a bit-multiplexed return-to-zero (RZ) signal into each signal at the optical level, and then converting it into an electrical signal for identification and reproduction.

The optical star coupler 300 divides the high-speed optical signal and supplies it to each system. Optical coupler 102, bistable laser diode 1
00, the photoelectric conversion element 200, the equalization amplifier 202, the low-pass filter 220, the voltage controlled oscillator 240, the electro-optical conversion element 260, and the identification regeneration circuit 280 are the same as those shown in FIG. 3, and have the same effect. It is intended to be presented. Therefore, the electrical signal output from the voltage controlled oscillator 240 and the optical sampling signal output from the electro-optical conversion element 260 are phase-locked to one of the bit- or byte-multiplexed high-speed optical signals, and the identification and regeneration circuit 280 identifies the signal. will be played.

When the bit rate of the multiplexed optical signal is B and the multiplicity is N, the delay circuit 302 converts the optical sampling signal output from the electro-optical conversion element 260 into n/B (n=12...N-1
) and is supplied to each other system as N-1 optical sampling signals. The delay circuit 302 is constituted by an optical fiber cable having a length corresponding to the time to be delayed. The delay circuit 304 converts the identification signal output from the voltage controlled oscillator 240 into n/B (n= 1 ・2 ・−N −1)
is delayed by N1 identification signals and supplied to other systems as N1 identification signals. The delay circuit 304 is composed of a coaxial cable having a length corresponding to a desired delay time.

The other systems each include a series connection of an optical coupler 102', a bistable laser diode 100', a photoelectric conversion element 200', an equalization amplifier 202', and an identification regeneration circuit 280'. Optical star coupler 3 is connected to optical coupler 102'.
One of the high-speed optical signals from 00 and one of the optical sampling signals from the delay circuit 302 are supplied to the identification and regeneration circuit 28.
0' is supplied with one of the identification signals from the delay circuit 304. Figure 5 (A).

Through the operations described in columns (B), (C), and (D), one of the multiplexed signals is separated in the bistable laser diode 100', converted into an electrical signal in the opto-electrical conversion element 200', and then sent to the identification reproducing circuit. The identification is reproduced at 280'.

In the circuit shown in FIG. 17, a combination of the optical coupler shown in FIG. 3 and a bistable laser diode into which current is continuously injected is used as the light extraction means, but as shown in FIG. A bistable laser diode whose injection current is controlled by a periodic signal, an optical gate element shown in Fig. 10, an optical wavelength conversion laser and selective transmission filter shown in Fig. 12, or a combination of a nonlinear optical element and an optical coupler shown in Fig. 15. Of course, it is also possible to replace them in combination.

〔Effect of the invention〕

As described above, according to the present invention, it becomes possible to receive and demodulate optical signals at a speed so high that it is impossible to directly convert them into electrical signals and process them now or in the future.

Furthermore, even if the optical signal is fast enough to be directly converted and processed, by separating and extracting it at the optical level to create a low-speed optical signal, it is possible to process it with a cheaper optical receiver. It becomes possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of the optical signal processing circuit of the present invention, and FIG. 2 is a diagram showing the basic configuration of the optical signal processing circuit of the present invention, which is a circuit for separating multiplexed optical signals. 3 is a diagram showing the first embodiment of the present invention, FIG. 4 is a diagram showing the characteristics of the bistable laser diode used in the circuit of FIG. 3, and FIG. 5 is a diagram showing the characteristics of the bistable laser diode used in the circuit of FIG. 6 and 7 are diagrams for explaining phase synchronization in the circuit of FIG. 3; FIG. 8 is a diagram showing the second embodiment of the present invention; FIG. 8 is a timing chart for explaining the operation of the circuit in FIG. 8, FIG. 10 is a diagram for explaining the third embodiment of the present invention, and FIG. 11 is a diagram for explaining the operation of the circuit in FIG. 10. , Fig. 12 is a diagram showing the fourth embodiment of the present invention, Fig. 13 is a diagram showing the characteristics of the optical wavelength conversion laser used in the circuit shown in Fig. 12, and Fig. 14 is a diagram showing the operation of the circuit shown in Fig. 12. FIG. 15 is a diagram showing the fifth embodiment of the present invention, FIG. 16 is a timing chart for explaining the operation of the circuit in FIG. 15, and FIG. 17 is a diagram showing the fifth embodiment of the present invention. FIG. 7 is a diagram showing a sixth embodiment. In the figure, 10... Light extraction means, 20... Photoelectric conversion means, 22... Average value calculation means, 24... Variable frequency oscillation means, 26... Electro-optical conversion means, 28...・Identification means.

Claims (1)

[Claims] 1. An optical signal processing circuit that separates and extracts signals from a high-speed optical signal consisting of a return-to-zero signal, the optical extraction circuit that separates and extracts a low-speed optical signal from the high-speed optical signal using a repetitive optical sampling signal. means (10); opto-electric conversion means (20) for converting the low-speed optical signal into a low-speed electric signal; and average value calculation means (2) for calculating the average value of the low-speed electric signal.
2), variable frequency oscillation means (24) that generates an electrical signal whose frequency changes according to the output of the average value calculation means (22), and electro-optical conversion of the output of the variable frequency oscillation means (24). electro-optical conversion means (26)
), and the output of the variable frequency oscillation means (24) is used as an identification signal,
An optical signal processing circuit comprising: identification means (28) for extracting a signal by identifying the low-speed electrical signal based on the timing of the identification signal. 2. An optical signal processing circuit that separates and extracts each signal from a high-speed optical signal consisting of a time-division multiplexed return-to-zero signal, comprising branching means (30) for branching the high-speed optical signal into a plurality of high-speed optical signals; , a plurality of optical extracting means (10, 10') for separating and extracting low-speed optical signals from the plurality of high-speed optical signals using repetitive optical sampling signals, and a plurality of optical extractors (10, 10') for respectively converting the low-speed optical signals into low-speed electrical signals. electrical conversion means (20, 20'); average value calculation means (22) for calculating the average value of the output of one photoelectric conversion means (20); and according to the output of the average value calculation means (22). A variable frequency oscillation means (24) that generates an electrical signal whose frequency changes, and converting the output of the variable frequency oscillation means (24) into an electro-optic converter to send a low-speed optical signal to the one opto-electric converter (20). an electro-optic conversion means (26) which supplies the light extraction means (10) as a repetitive optical sampling signal; and extracts each of the signals by respectively identifying the low-speed electrical signals based on the timing of the identification signal. Among the plurality of identification means (28, 28'), the identification signal of one identification means (28) supplied with a low-speed electric signal from the one opto-electrical conversion means (20) is transmitted to the variable frequency oscillation means (20).
4), the outputs of the plurality of identification means (28, 28') and the electro-optical conversion means (26) are given different delays, respectively, and the light is repeatedly sampled to the other light extraction means (10'). An optical delay means (32) that supplies the output as a signal; and an electric delay means (34) that gives different delays to the output of the variable frequency oscillation means (24) and supplies them to other identification means (28') as identification means. ). An optical signal processing circuit comprising: 3. The optical signal extraction means (10, 10') includes an optical combining circuit that combines the optical signal and the repetitive optical sampling signal, and an element that has irreversible optical threshold characteristics in the relationship between input light and output light. and an element to which the output of the optical combining circuit is supplied as input light, and the signal serving as the identification signal is also supplied to the element as a reset signal for resetting the optical output of the element belonging to the same system. Claim 1 or 2 provided
The optical signal processing circuit described. 4. The optical signal extracting means (10, 10') comprises an optical combining circuit that combines the optical signal and the repetitive optical sampling signal, and an element having optical hysteresis characteristics in the relationship between the input light and the output light. 3. The optical signal processing circuit according to claim 1, further comprising an element to which the output of the optical combining circuit is supplied as input light. 5. The optical signal extracting means (10, 10') includes an optical combining circuit that combines the optical signal and the repetitive optical sampling signal; the wavelength of the input optical signal is equal to the wavelength of the high-speed optical signal; 3. An optical gate element whose signal wavelength is equal to the wavelength of said repetitive optical sampling signal, and an optical gate element into which the output of said optical combining circuit is input.
The optical signal processing circuit described. 6. The wavelength of the high-speed optical signal and the repetitive optical sampling signal are substantially equal, and the optical signal extraction means (10, 10') is configured to generate an optical signal that combines the optical signal and the repetitive optical sampling signal. a converging circuit, and a wavelength conversion element that outputs an optical signal with a wavelength different from the wavelength of the input optical signal, and outputs an optical signal with a wavelength equal to the wavelength of the input optical signal for input optical signals having a predetermined intensity or more. 3. The optical signal processing circuit according to claim 1, further comprising a wavelength conversion element into which the output of the optical combining circuit is input. 7. The optical signal extraction means (10, 10') comprises: an optical merging circuit for merging the optical signal and the repetitive optical sampling signal; and a nonlinear optical element having a quantum well structure; 3. The optical signal processing circuit according to claim 1, further comprising a nonlinear optical element to which an output is input. 8. The average value calculation means (22) is a low-pass filter that passes only the low-frequency component of the low-speed optical signal, and the variable oscillation means (24) adjusts the output signal according to the output voltage of the low-pass filter. The optical signal processing circuit according to any one of claims 1 to 7, which is a voltage controlled oscillator whose frequency changes.