JP2004326087A - Embodying equipment and its method for all-optical nor gate using gain saturation of semiconductor optical amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide embodying equipment and its method for embodying, specially, a 10 Gbits/s all-optical NOR logic element in a logic element by using a light signal transmitted from an arbitrary point in an optical circuit like optical computing for a pump signal and an irradiation signal. <P>SOLUTION: An A+B signal which is the total of input signals of an input signal pattern (A) of 1100 and an input pattern (B) of 0110 is used for the pump signal (1110), and a clock signal is generated with the input signal pattern (A) of 1100 and used for the irradiation signal (1111), which is made incident on a semiconductor optical amplifier (SOA) together with the pump signal at the same time to obtain Boolean logical expressions (A+B). Consequently, a NOR logic element is embodied by an XGM (Cross Gain Modulation) method using a gain saturation characteristic of the semiconductor optical amplifier, so the structure is simplified and all-optical logic elements for other functions are constituted by the same method. Consequently, the all-optical logic element performs an important duty for all-optical circuit and all-optical system embodiments. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an embodying equipment and its method for an all-optical NOR gate using gain saturation of a semiconductor optical amplifier using a gain saturation characteristic of a semiconductor optical amplifier. More specifically, a logic element that performs an all-optical logic operation using an optical signal transmitted from an arbitrary point of an optical circuit such as optical computing as a pump signal and an irradiation signal, and particularly a 10 Gbit / s all-optical The present invention relates to an apparatus for implementing a logical NOR logic element and a method for implementing the same.

  According to recent trends, the demand for higher speed and larger capacity of the system is increasing geometrically.

  Many systems are now largely based on silicon materials, ie electrical signals, and their future dependencies are uncertain because of the large barriers of speed and limited information processing capacity.

  In more detail, systems using optical elements based on indium phosphide (InP), on the other hand, can sufficiently solve the above problems in all aspects such as speed and information processing capacity. It is expected to be.

  Generally, when a system is configured, a method of integrating based on a single logic element (AND, OR, XOR, NAND, NOR, NXOR) is used, but even in a system using light The same is true.

  Logic elements having two stable states, called logic 0 and 1, are the basic building blocks of digital computers.

  The computer encodes all information using these two logical states (bits).

  Therefore, all-optical logic elements will undoubtedly play an important role in developing all-optical and opto-electric systems for future information technology.

  Until now, all-optical logic elements for ultra-high-speed optical information processing have been realized by using a nonlinear structure of light or by utilizing a wavelength conversion method.

In particular, all-optical NOR logic elements using the nonlinear gain of a semiconductor optical amplifier (SOA) have been developed as described in Non-Patent Documents 1 to 4.
NOR using a single optical path (arm) Single-arm ultrafast nonlinear interferometer (UN) [NS Patel, KL Hall, and KA Rauschenbach, Opt. Lett., 21, 1466 (1996)] All-optical NOR embodied by two pump signals of a single wavelength [A. Sharaiha, HW Li, F. Matchese and J, Le bihan, Electron. Lett., 33, 323 (1997)] All-optical NOR using pump signals of two different wavelengths [Byeong Young-tae, Kim Sang-hyuk, Kim Dong-hwan, U-dok-ha, Kim-sung-ho, New Physics, 40, 560 (2000); Young Tae Byun, Sang Hyuck Kim, Deok Ha Woo, Seok Lee, Dong Hwan Kim, Sun Ho Kim, “Apparatus and Method for Realizing All-Optical NOR Logic Device”, Patent No. (US 6,424,438 B1), Date of Patent (Jul. 23, 2002)]. All-optical NOR implemented by connecting two semiconductor optical amplifiers (Ali Hamie, Ammar Sharaiha, Mikael Guegan, and Benoit Pucel, IEEE Photon. Technol. Lett., 14, 1439 (2002)

  As described in Non-Patent Document 1, the all-optical NOR logic element using UNI has the advantage of high operation speed, but the core component is an optical fiber element, which is complicated, and it is difficult to integrate with other elements. It is difficult to apply to an optical operation system that requires integration.

  On the other hand, all-optical logic elements using a single SOA are stable, have a small system size, are easy to couple with other optical elements, and have advantages that are independent of polarization and wavelength. [T. Fjelde, D. Wolfson, A. Kloch, B. Dagens, A. Coquelin, I. Guillemot, F, Gaborit, F. Poingt, and M. Renaud, Electron. Lett., 36, 1863 (2000) ].

  However, when only the nonlinear characteristics of a single SOA are used without an optical fiber interference system, the structure of an all-optical NOR element is simple and integration with other elements is possible, but the operating speed is slower at 100 MHz or less.

  Also, as in Non-Patent Document 4, an all-optical NOR element realized by connecting two SOAs has a characteristic that the extinction ratio (ON / OFF ratio) is improved over a wider wavelength range than when a single SOA is used. However, there is a disadvantage that the operation speed is as low as 62.5 MHz.

  That is, in Non-Patent Documents 2 to 4 which are existing all-optical NOR logic elements that do not use an optical fiber interference system, a pump signal (Pump signal) uses a square wave to return to non-zero (NRZ: non-zero). (return to zero) pattern, and a continuous wave (CW) laser beam is used as an irradiation signal (probe signal).

  In this case, the operation speed of the all-optical NOR logic element is limited to 100 MHz or less by the NRZ pattern and the continuous wave (CW) type.

  Therefore, the development of an all-optical NOR logic device that has a simple structure, not only can be integrated with other optical devices, but also has an operation speed improved to several GHz to several tens of GHz is urgently needed. Required.

  An object of the present invention is to provide a technology for realizing a 10 Gbit / s all-optical NOR logic element by using the gain saturation characteristic of a semiconductor optical amplifier, as devised in view of the above-mentioned necessity. .

To achieve the above object, the present invention provides an input signal pattern A of 1100 and an A + B signal, which is a sum of input signals of an input signal pattern B of 0110, as a pump signal (1110). A clock signal is formed by the signal pattern A and used for the irradiation signal (1111), and the irradiation signal and the pump signal are simultaneously incident on the semiconductor optical amplifier (SOA) in the opposite directions, and a Boolean logic expression (A + B) And a method for implementing an all-optical NOR logic element using gain saturation of a semiconductor amplifier.
In order to achieve the above object, the present invention uses an input signal pattern A of 1100 and an input signal pattern B of 0110 to create an A + B signal, which is a total of input signals, to produce a pump signal (1110). Pump signal implementation means to be used, irradiation signal implementation means to make a clock signal with the input signal pattern A of the 1100 and use it for the irradiation signal (1111), and simultaneously apply the irradiation signal and the pump signal to the semiconductor amplifier (SOA) in the opposite direction. It is an object of the present invention to provide an all-optical NOR logic element implementation device using gain saturation of a semiconductor optical amplifier including a NOR implementation means for obtaining a Boolean logic expression (A + B).

All-optical NOR logic, together with other single all-optical logic elements (OR, NAND, AND, XOR, NXOR), is the core logic that is essential when configuring computing and all-optical signal processing systems. Element.
NOR is the core element of the full adder, which is the basis of all logic calculations, and applies to almost all logic systems.
In particular, since the all-optical NOR logic element according to the present invention is embodied by an XGM (Cross Gain Modulation) method using the gain saturation characteristic of the semiconductor optical amplifier, the structure is simple, and the all-optical logic element having other functions is used. Since it can be configured in the same manner, it is expected to play an important role in implementing all-optical circuits and all-optical systems.
Therefore, if an efficient integration technique of all-optical logic elements is developed, all controls can be performed only by optical signals without depending on electrical signals.

Hereinafter, the configuration and operation of an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 conceptually illustrates the operating principle of an all-optical NOR logic element.
In the present invention, in order to improve the operation speed, the irradiation signal (probe signal) and the pump signal (pump signal) are all generated by a signal of a return to zero (RZ) pattern.

  If a pump signal having a high light intensity is incident on the SOA, a carrier depletion phenomenon occurs in the SOA.

  Therefore, since the irradiation signal in the form of a pulse having a constant period is modulated and output in the SOA in the same manner as the gain modulation due to carrier depletion, the output signal has a logic opposite to that of the pump signal. Become like

  However, when a pulse signal is used, since the pulse On-Off difference is large, the magnitude of the signal output when there is no pulse signal can be regarded as 0, which is very small.

  Therefore, when there is no pulse signal of the irradiation signal, the output signal becomes 0 regardless of the pump signal.

2A and 2B are a basic configuration of an all-optical NOR logic element and a NOR logic table.
In FIG. 2A, assuming that the pulse signal is in the ON state when there is a pulse and the OFF state when there is no pulse, the clock signal passes through the SOA and the output signal is in the ON state when the pump signal is in the OFF state.

  Therefore, if the A signal and the B signal are combined and then injected into the SOA in the opposite directions together with the clock signal as shown in FIG. 2A, a Boolean logic expression that is the NOR value of the A and B signals (A + B) is obtained.

  This means that the NOR logic element shown in FIG. 2B matches the Boolean value of the truth table, so that the all-optical NOR logic element can be implemented using a single SOA.

FIG. 3 is a diagram illustrating an apparatus for implementing an all-optical NOR logic element.
The input signal patterns A and B of the all-optical NOR logic element are made with a mode-locked fiber laser (MLFL) having a wavelength of 1550 nm.

The mode-locked optical fiber laser (MLFL) is driven at 2.5 GHz having a period of 400 ps by a pulse generator (PG).
At this time, the width of the generated pulse is approximately 38 ps.

  The output of the mode-locked optical fiber laser (MLFL) is first separated by a 50:50 fiber coupler (FC1), and then a variable delay (Variable) as a delay means to obtain a time delay of 100 ps. Delay: VD1), optical attenuator (Attenuator: ATTN1) as a control means, and polarization controller (Polarization Controller: PC1), then secondly match with 50:50 optical fiber coupler (FC2) As a result, an input signal pattern A (1100) operated at 10 Gbit / s is generated.

  Then, the upper optical fiber at the output end of the second 50:50 optical fiber coupler (FC2) is separated from the fourth 50:50 optical fiber coupler (FC4).

  Of these, the incident light (1100) of the upper optical fiber passes through the variable delay device (VD2) of the delay means to obtain a time delay of 100 ps, whereby the input signal pattern B (0110) is created, and the lower light The incident light (1100) of the fiber passes through a polarization adjuster (PC2) and an optical attenuator (ATTN2) as adjusting means.

  Then, the output light (B) of the upper optical fiber and the output light (A) of the lower optical fiber are combined by a fifth 50:50 optical fiber coupler (FC5), so that the total of the input signal patterns A and B is obtained. A + B (1110) is generated.

  On the other hand, the input signal pattern A (1100) coupled to the lower optical fiber of the second 50:50 optical fiber coupler (FC2) is separated from the sixth 50:50 optical fiber coupler (FC6), The incident light (1100) of the lower optical fiber passes through a variable delay device (VD3) which is a delay means to obtain a time delay of 200 ps, and the incident light (1100) of the lower optical fiber is a polarization adjuster (which is an adjusting means). The clock signal pattern (1111) is created by passing through the PC3) and the optical attenuator (ATTN3) and combining them at the seventh optical fiber coupler (FC7).

  The fifth 50:50 fiber optic coupler (FC5) pump signal pattern A + B (1110) of the optical fiber above the output end is amplified by an Er-doped optical fiber amplifier (EDFA) and optically circulated. After passing through the device (C), the light enters the semiconductor optical amplifier (SOA) in the direction opposite to the irradiation signal pattern of the upper optical fiber at the output end of the seventh 50:50 optical fiber coupler (FC7).

  When an irradiation signal and a pump signal with different wavelengths are incident on a semiconductor amplifier (SOA) from the same direction, an optical filter is required to separate the irradiation signals [Young Tae Byun, Jae Hun Kim, Young Min Jeon, Seok , Deok Ha Woo, and Sun Ho Kim, “An All-Optical OR Gate by using casacaded SOAs, '2002 International Topical meeting on Photonics in Switching, Hyatt Regency (Cheju Island, KOREA), 187 (2002).].

  However, when the two signals are incident on the semiconductor optical amplifier (SOA) in opposite directions, not only the optical filter is not necessary, but also the wavelength of the irradiation signal and the pump signal may be the same.

  At this time, a Boolean signal having a 0001 pattern in which the gain of the A + B signal is modulated by the gain saturation of the semiconductor optical amplifier (SOA) is obtained.

  In the present invention, the case where the wavelengths of the irradiation signal and the pump signal are the same is described as an example. However, even when the wavelengths are different, the operation of the all-optical NOR logic element can be obtained by the above method.

  Unexplained symbols ISO is an optical isolator, PD is a photodetector, and OSC is an oscilloscope, which is a signal analyzer.

FIG. 4 is a diagram showing characteristics of an all-optical NOR logic element operated at 10 Gbit / s.
FIG. 4A shows an input signal pattern A having a 1100 pattern output from the third 50:50 optical fiber coupler (FC3), and FIG. 4B shows a fifth 50:50 optical fiber coupler. FIG. 4C shows an input signal pattern B having a pattern of 0110 measured by the fiber coupler (FC5). FIG. 4C shows the input signal pattern B at the lower end of the fifth 50:50 optical fiber coupler (FC5) output end. The sum of the measured input signal patterns A and B is A + B. FIG. 4D shows the pattern of the clock signal measured on the lower optical fiber at the output end of the seventh 50:50 optical fiber coupler (FC7). It is.

  FIG. 4E is made when the A + B pattern (1110), which is the sum of the two input signal patterns, passes through the semiconductor optical amplifier (SOA) in the opposite direction to the clock signal pattern (1111) as the irradiation signal. When the logic signal is (1,0), (1,1), (0,1) in the output waveform, there is no output light, and only when (0,0), there is output light.

  Therefore, when the light intensities of the investigation signal and the pump signal are 0.3 dBm and 10.8 dBm, respectively, it is confirmed that the operation characteristics of the all-optical NOR logic element are realized.

  Each of the above mentioned optical signals was measured using a 40 Ghz photodetector and sampling oscilloscope.

  As described above, according to the present invention, four logic signals [(1,0), (1,1), (0, 1) are obtained by two input signal patterns A (1100) and B (0110) of the same wavelength. 1), (0,0)], and after the input signal pattern A (1100) is separated, one signal is delayed by 200 ps and the other signal (A) By combining, an irradiation signal (1111) is obtained.

  Then, when the pump signal and the irradiation signal cross the semiconductor amplifier (SOA) in opposite directions, a 10 Gbit / s all-optical logic NOR logic element has been successfully implemented due to the gain saturation characteristic of the SOA.

  That is, the output signal is logic 1 only when the A signal having the 1100 pattern and the B signal having the 0110 pattern are all logic 0, and all other signals have the logic 0.

  Since this result matches the truth table of the Boolean NOR in FIG. 2B, the invention of the all-optical NOR logic element is experimentally recognized.

Therefore, according to the present invention, it is easy to implement all-optical logic operation on a complex optical path of a computing and all-optical signal processing system.

FIG. 4 is a characteristic diagram illustrating an operation principle of the all-optical NOR logic element. 3 is a basic configuration and a truth table of an all-optical NOR logic element. 1 is a configuration diagram of an apparatus for implementing an all-optical NOR logic element according to the present invention; FIG. 4 is a characteristic diagram of an all-optical NOR logic element operating at 10 Gbit / s according to the present invention.

Explanation of reference numerals

ATTN1, ATTN2, ATTN3 ... optical attenuator, C ... optical circulator, FDFA ... erbium-doped optical fiber amplifier, FC1, ..., FC7 ... optical fiber coupler, ISO ... Optical isolator, MLFL: Mode-locked optical fiber laser, OTDM MUX: Optical time division multiplexing device, OSC: Oscilloscope, PC1, PC2, PC3: Polarization controller, PD -Photodetector, PG: pulse generator, SOA: semiconductor optical amplifier, VD1, VD2, VD3: variable delay device.

Claims (14)

The A + B signal, which is the sum of the input signals of the input signal pattern A of 1100 and the input signal pattern B of 0110, is used as the pump signal (1110) to form a clock signal with the input signal pattern A of 1100 and the irradiation signal (1111). Use
The irradiation signal and the pump signal are simultaneously incident on the semiconductor amplifier (SOA) in opposite directions,
A method for implementing an all-optical NOR logic device using gain saturation of a semiconductor optical amplifier, wherein a Boolean logic expression ~ (A + B) is obtained.   2. The pump signal according to claim 1, wherein the modulating waveform of the mode-locked optical fiber laser is multiplexed to generate an input signal pattern A of 1100, and the input signal of 1100 is time-delayed to generate an input signal pattern B of 0110. A method for implementing an all-optical NOR logic element using gain saturation of a semiconductor optical amplifier, wherein the sum of two input signals obtained using a fiber coupler is an A + B signal.   3. The all-optical NOR using gain saturation of a semiconductor optical amplifier according to claim 2, wherein the mode-locked optical fiber laser operates at 2.5 GHz, has a wavelength of 1550 nm, and is multiplexed at 10 Gbit / s. A method for implementing a logic element.   3. The method according to claim 2, wherein a time delay of the input signal of 1100 is 100 ps.   2. The semiconductor optical amplifier according to claim 1, wherein the irradiation signal is a clock signal obtained by time-delaying the input signal pattern A of the 1100 and then multiplexing the input signal pattern A without delay. For implementing an all-optical NOR logic element using gain saturation.   6. The method of claim 5, wherein the irradiation signal has a delay time of 200 ps of the input signal of the 1100, and the gain saturation of the semiconductor optical amplifier is used.   2. The gain saturation of a semiconductor optical amplifier according to claim 1, wherein the irradiation signal and the pump signal are all incident on the SOA in pulse form to implement a NOR logic element by an XGM (Cross Gain Modulation) method. A method for realizing an all-optical NOR logic element using the method.   6. The method according to claim 1, wherein the wavelength of the irradiation signal and the wavelength of the pump signal are different from each other. . A pump signal implementing means for generating an A + B signal as a total of the input signals by using the input signal pattern A of 1100 and the input signal pattern B of 0110, and using the pump signal (1110);
Irradiation signal implementation means for creating a clock signal with the input signal pattern A of the 1100 and using the illumination signal (1111),
The irradiation signal and the pump signal are simultaneously incident on the semiconductor amplifier (SOA) in the opposite direction, and a Boolean logic formula ~ (A + B) NOR implementation means for obtaining the gain of the semiconductor optical amplifier characterized by including An apparatus for implementing an all-optical NOR logic element using saturation.   10. The pattern signal implementing means according to claim 9, wherein the pump signal implementing means multiplexes a modulated waveform of a mode-locked optical fiber laser (MLFL) to form an input signal pattern A of 1100, and a time delay of the input signal of 1100. A pattern B implementing means for generating an input signal pattern B of 0110, and an A + B implementing means for producing an A + B signal which is a total of two input signals obtained by using the fifth optical fiber coupler. For implementing an all-optical NOR logic element using gain saturation of a semiconductor optical amplifier.   11. A mode-locked optical fiber laser according to claim 10, wherein the pattern-A implementing means is driven by a pulse generator and outputs a light of a certain wavelength, and a first optical fiber coupling for separating output light of the mode-locked optical fiber laser. A first variable delay device for delaying one of the output lights separated by the first optical fiber coupler, a first optical attenuator for adjusting the other output light separated by the first optical fiber coupler, and An all-optical device using gain saturation of a semiconductor optical amplifier, comprising a first polarization controller and a second optical fiber coupler combining the delayed output light and the adjusted output light. Equipment for implementing NOR logic elements.   12. The optical fiber coupling device according to claim 11, wherein the pattern B implementing means comprises: a fourth optical fiber coupler for separating an output of a third optical fiber coupler connected to an output of the second optical fiber coupler; A second variable delay device for delaying one of the output lights separated by the optical fiber coupler, a second optical attenuator for adjusting the other output light separated by the fourth optical fiber coupler, and a second polarization adjuster. An apparatus for implementing an all-optical NOR logic element using gain saturation of a semiconductor optical amplifier.   10. The irradiating signal implementation unit according to claim 9, wherein the irradiating signal implementation unit includes a sixth optical fiber coupler for separating an output of the input signal pattern A of the 1100, and a second optical fiber coupler for delaying one output light separated by the sixth optical fiber coupler. A third variable delay device, a third optical attenuator and a third polarization adjuster for adjusting the other output light separated from the sixth optical fiber coupler, and the delayed output light and the adjusted output light. An apparatus for implementing an all-optical NOR logic element using gain saturation of a semiconductor optical amplifier, comprising a seventh optical fiber coupler.   10. The optical pickup device according to claim 9, wherein the NOR implementing means comprises: an erbium-doped optical fiber amplifier (EDFA) for amplifying the pump signal; an optical circulating device for injecting the amplified pump signal into one of the semiconductor optical amplifiers; Is incident on one side, and when the irradiation signal is incident on the other side, the gain saturation characteristic causes the gain of the pump signal to be modulated. An apparatus for implementing an all-optical NOR logic element using gain saturation of a semiconductor optical amplifier, characterized by comprising:

Images