JPH095812A - Optical logic element and optical logic circuit using the optical logic element - Google Patents

Abstract

PURPOSE: To provide an optical logic element capable of executing the optical control operation similar to the control operation of an electric logic element with the light itself and the optical logic circuit. CONSTITUTION: Incident light incident waveguides 3a, 3b are connected to a nonlinear waveguide 6a and the exit end side is provided with an analyzer 9a to form an AND circuit optical element 13. Incident light incident waveguides 4a, 4b, are connected to a nonlinear waveguide 6b and the exist end side is provided with an analyzer 9b to form a NOT circuit optical element 14 which is directly connected to an optical element 13. The respective incident light incident waveguides 3a, 3b are provided with optically active substances which deviate the plane of polarization of incident polarized light (input light (a), (b)) by the same angle exclusive of 90 deg. from the speed axis of the nonlinear waveguide 6a and the incident light incident waveguides 4a, 4b are provided with the similar optically active substances. The optical NAND circuit which outputs the light rays from an output terminal 18 exclusive of the time when both of the input light lays (a), (b) are made incident by selectively outputting only the light rays subjected to phase transition at a prescribed angle among the propagated light rays of the respective nonlinear waveguides 6a, 6b are analyzers 9a, 9b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical logic element used in a future optical computer for processing information using light and an optical logic circuit using the optical logic element.

[0002]

2. Description of the Related Art Conventionally, as an element for controlling light, for example, an electrode is provided in an optical waveguide, and a refractive index of the optical waveguide is changed by applying a voltage to the electrode, and a path of light propagating in the optical waveguide is changed. The optical switch to change is under study. Further, instead of providing an electrode in the optical waveguide, by doping the optical waveguide itself with an organic or inorganic substance, the nonlinear effect that the light passing through the optical waveguide changes its refractive index depending on its light intensity, Diversion of light,
An element that performs switching is also being studied.

[0003]

However, in particular,
In future optical computers, which are being considered for use as ultra-high-speed and large-capacity information processing equipment, not only the above-mentioned light diversion and switching, but also electric logic elements and logic circuits (for example, NAND circuits) And O
It is considered that an optical element and an optical circuit capable of performing an optical signal control similar to the electric signal control operation by the R circuit) are required, but conventionally, such an optical logic element and an optical logic circuit have not been proposed.

The present invention has been made to solve the above problems, and an object thereof is an optical signal control operation similar to an electric signal control operation by an electrical logic element and a logic circuit, which can be controlled by the light itself. It is to provide a logic element and an optical logic circuit using the optical logic element.

[0005]

In order to achieve the above object, the present invention is constructed as follows. That is, in the optical logic element of the present invention, two incident light incident waveguides are connected to one non-linear waveguide that performs non-linear polarization rotation of light via a confluence point, and the two non-linear waveguides are connected to each other. Due to the polarization dispersion of the nonlinear waveguide, a slow axis which is a polarization component axis having a slow light propagation speed and a fast axis having a light propagation speed faster than the slow axis are orthogonal to each other, and The two incident light incident waveguides are formed so as to be orthogonal to the optical axis of the nonlinear waveguide, and the polarization planes of the incident polarized light incident on the nonlinear waveguides from the respective incident light incident waveguides are set to the nonlinear plane. A polarization plane adjusting means for shifting the waveguide from the fast axis or the slow axis by the same angle other than 90 degrees is provided.

Further, the nonlinear refractive index and the length of the nonlinear waveguide are such that when the incident polarized light is incident from only one of the two incident light incident waveguides, the incident polarized light is the nonlinear waveguide. Is adjusted so that the phase change when propagating through the output end changes at a predetermined angle at the output end, and the output end side of the nonlinear waveguide has a predetermined angle among the propagating light of the nonlinear waveguide. It is also a characteristic configuration of the optical logic element of the present invention that an output selection means for selectively outputting only the phase-changed propagating light is provided.

Further, an optical logic circuit using the optical logic element of the present invention is characterized in that a plurality of the optical logic elements having the above-mentioned configuration are combined and connected.

[0008]

In the present invention having the above-mentioned structure, since polarization plane adjusting means is provided for each of the two incident light incident waveguides, incident polarized light incident from each incident light incident waveguide is nonlinear. When entering the waveguide, the polarization plane of the incident polarized light is from the fast axis or slow axis, which is the polarization component axis of the nonlinear waveguide.
The incident polarized light is shifted by the same angle other than 90 degrees, and the incident polarized light propagates through the nonlinear waveguide while its polarization plane rotates.

The angle change of the polarization plane rotation of the incident polarized light, that is, the phase change, changes by the angle shown in the following expression (1).

Φ = 2πn ₂ | E | ² L / λ (1)

In the equation (1), φ is the phase, λ is the wavelength of the incident polarized light, n ₂ is the nonlinear refractive index of the nonlinear waveguide, | E | ² is the electric field intensity of light, and L is the nonlinear waveguide. Is the length.

As is clear from the equation (1), if the electric field intensity of the light propagating through the nonlinear waveguide is doubled, the magnitude of the phase change is also doubled.
For each phase change at the exit end of the nonlinear waveguide when the incident polarized light is incident from one of the two incident light incident waveguides and propagated through the nonlinear waveguide, The phase change at the exit end of the nonlinear waveguide when the incident polarized light of the same wavelength and the same wavelength as that of the incident polarized light is propagated through the nonlinear waveguide from both of the waveguides is doubled.

In this way, when the incident polarized light is made incident from either one of the two incident light incident waveguides,
Taking advantage of the difference in phase change at the exit end of the nonlinear waveguide when incident polarized light is incident from both, for example, incident polarized light is incident from one of the two incident light incident waveguides. Adjust the phase change when propagating through the nonlinear waveguide so that it changes at a predetermined angle, such as 180 degrees, at the exit end of the nonlinear waveguide. Is incident, the incident polarized light becomes linearly polarized light → elliptically polarized light → circularly polarized light → elliptically polarized light → linearly polarized light due to the phase change, and becomes linearly polarized light at the exit end of the nonlinear waveguide.

When incident polarized light of linear polarization having the same wavelength and the same intensity as the incident polarized light is incident from each of the two incident light incident waveguides, the incident polarized light propagates through the nonlinear waveguide. The phase change will change 360 degrees at the exit end of the nonlinear waveguide, and becomes linear polarization → elliptical polarization → circular polarization → elliptical polarization → linear polarization → elliptical polarization → circular polarization → elliptical polarization → linear polarization. The light is linearly polarized at the exit end of.

Thus, even when the incident polarized light of linear polarization is incident from one of the incident light incident waveguides, the incident polarized light of linear polarization is incident from each of the two incident light incident waveguides. At this time, both are linearly polarized light at the exit end of the nonlinear waveguide, but the
Since the polarized waves that have undergone a phase change of 0 degrees are orthogonal to each other, for example, the polarization axis of the linearly polarized light after being subjected to a phase change of 180 degrees and the light transmission direction are perpendicular. If an output selection means, etc., that selectively transmits only the propagating light that has undergone a 360-degree phase change, is provided on the output end side of the nonlinear waveguide, only the propagating light that has undergone a 360-degree phase change will be transmitted. The propagating light that has been output and has undergone a phase change of 180 degrees will not be output.

Then, as shown in Table 1 below, 2
Of the two incident light incident waveguides, light is output from the nonlinear waveguide only when incident polarized light (referred to as input lights a and b) is incident from each of the two incident light incident waveguides. , B, no light is output from the nonlinear waveguide, and the same control operation as that of the AND circuit, which is one of the electrical logic elements, is performed by light. In the table below, reference numeral 1 indicates a state with input or output, and reference numeral 0 indicates a state without input or output.

[0017]

[Table 1]

Of the two incident incident waveguides, one side is an incident waveguide of probe light as incident polarized light,
If the length of the nonlinear waveguide is adjusted so that the phase change when the probe light propagates through the nonlinear waveguide becomes a predetermined 180 ° at the exit end when only the probe light is incident, When incident polarized light (input light) from the incident light incident waveguide is incident, the phase change of the combined light of the incident polarized light and the probe light at the time of nonlinear waveguide propagation is 2 at the angle (180 degrees). Double angle (360
Degree).

At this time, at the exit end of the nonlinear waveguide, the polarization axis of the probe light that has undergone a phase change of 180 degrees is parallel to the light transmission direction, and this light is selectively output. If the output selection means is provided, as shown in Table 2, light is output from the nonlinear waveguide only when the probe light is present, and there is no output from the nonlinear waveguide when the input light is input in addition to the probe light. Then, the control operation similar to the control operation of the NOT circuit, which is an electric logic element, is performed by light.

[0020]

[Table 2]

As described above, in the optical logic device according to the present invention, by appropriately forming the nonlinear refractive index and the length of the nonlinear waveguide as described above, an electrical AND circuit and N
In the optical logic circuit of the present invention in which an optical logic element that performs a control operation by light such as an OT circuit is formed, and a plurality of the optical logic elements are combined and connected, depending on the combination connection method, for example, an electric NAND circuit or An optical logic circuit that performs optical control similar to the electrical control operation of the OR circuit is formed.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a main part configuration of a first embodiment of an optical logic device according to the present invention. The optical logic circuit of the present embodiment is formed on a quartz substrate, and the AND circuit as the optical logic element shown in FIG. 2 is provided on the emission end side of the optical element 13 and the NOT circuit as the optical logic element shown in FIG. It is formed by connecting the optical elements 14 in series.

In the AND circuit optical element 13, two incident light incident waveguides 3a and 3b are jointly connected via a confluence point A to one non-linear waveguide 6a which performs non-linear polarization rotation of light. In the non-linear waveguide 6a, the cross-sections of the non-linear waveguide in the axial directions perpendicular to each other, that is, the non-linear waveguide 6a,
When the optical axis of a is formed in the Z-axis direction of FIG. 6, there is a difference in the refractive index in the X-axis direction and the Y-axis direction orthogonal to the Z-axis.

Due to this difference in refractive index, different polarization dispersion occurs in the non-linear waveguide in the X-axis direction and the Y-axis direction, and due to this polarization dispersion, the propagation speed of light is slow. The slow axis which is the polarization component axis and the fast axis whose light propagation speed is faster than this slow axis are orthogonal to each other, and the nonlinear waveguide 6a
Is formed orthogonal to the optical axis Z of. That is, assuming that the fast axis is formed in the X direction of FIG. 6, the slow axis is formed in the Y axis direction of the figure in the nonlinear waveguide 6a.

Input light input terminals as incident polarized light are connected to the incident end sides of the incident light incident waveguides 3a and 3b, respectively, and the fast axis (see FIG. 6) of the nonlinear waveguide 6a is connected from these input terminals. Input lights a and b having the same intensity and the same wavelength are respectively input. The light linearly polarized in the X-axis direction is linearly polarized light having a plane of polarization formed on the XZ plane, as shown in FIG.

In addition, the polarization planes of the incident polarized light beams incident from the incident light incident waveguides 3a and 3b are respectively applied to the incident light incident waveguides 3a and 3b by the fast axis of the nonlinear waveguide 6a (X in FIG. 6). (Axial direction) is provided with an optical rotatory substance as a polarization plane adjusting means for shifting by the same angle other than 90 degrees. This optically active substance is, for example, crystal, glucose,
Since it has a helical structure such as sucrose or tartaric acid, it has optical rotatory power and has a function of rotating the polarization vector of the incident polarized light entering the incident light incident waveguides 3a and 3b. Such an optical rotatory substance is provided in a state of being doped in quartz or the like forming the incident light incident waveguide.

By the way, when the polarized light propagates through the above-mentioned nonlinear waveguide and the plane of polarization of this polarized light is deviated from the fast axis and the slow axis of the nonlinear waveguide, the polarized light in the nonlinear waveguide 6a. Due to the difference between the electric field component in the fast axis direction (X axis direction) and the electric field component in the slow axis direction (Y axis direction), which is the component axis, as described above, the phase is the amount represented by the formula (1). A phenomenon called non-linear polarization rotation that shifts is generated. For example, when there is only one input light input to the nonlinear waveguide 6a and when there are two input lights (the light intensity in this case is one input light). The phase change (polarization plane rotation angle) when two input lights are input is doubled.

The phase change is caused by the nonlinear waveguide 6a.
Is proportional to the non-linear refractive index n ₂ of the non-linear waveguide 6a and the length L of the non-linear waveguide 6a, the non-linear refractive index n ₂ of the non-linear waveguide 6a is increased when the phase change is set to a certain magnitude. The length L of the waveguide 6a can be shortened to shorten the length of the optical logic element.

In the present embodiment, when the incident polarized light is incident from only one of the two incident light incident waveguides 3a and 3b (when the input light is input), the incident polarized light is reflected by the nonlinear waveguide. The phase change when propagating through 6a
The nonlinear refractive index and the length L of the nonlinear waveguide 6a are changed so as to change at a predetermined 180 degree angle at the exit end of a.
₁ is adjusted so that when incident polarized light is incident from both of the incident light incident waveguides 3a and 3b, when the combined light of these incident polarized lights propagates, The phase changes according to the angle. As described above, when the linearly polarized incident polarized light propagates through the nonlinear waveguide and undergoes a phase change of 180 degrees and 360 degrees, both of the propagated light are linearly polarized at the exit end of the nonlinear waveguide. Waves are formed, and their polarization planes are formed at angles orthogonal to each other.

As shown in FIGS. 1 and 2, the nonlinear waveguide 6a
An analyzer 9a is provided on the emission end side of. The analyzer 9a is formed so that its light transmission direction is perpendicular to the polarization axis of linearly polarized light after undergoing a phase change of 180 degrees. In other words, the analyzer 9a is 180 degrees. The linearly polarized light that is orthogonal to the light that has undergone the phase change, that is, only the linearly polarized light that has undergone the 360 ° phase change, is selectively output. In this way, the analyzer 9a , A predetermined angle (360 degrees) of the propagation light of the nonlinear waveguide 6a.
The output selection means selectively outputs only the propagating light whose phase is changed by (degrees).

In this embodiment, as shown in FIG.
Electrodes 8 are provided at both ends of the non-linear waveguide 6a of the AND circuit optical element 13, and a voltage is applied to the electrodes 8 so that the non-linear polarization rotation amount of the polarized light passing through the non-linear waveguide 6a is optimized for logical operation. The optical waveguide (not shown) for propagating the reflected light reflected by the analyzer 9a is formed at the connection point between the nonlinear waveguide 6a and the analyzer 9a. .

The AND circuit optical element 13 is configured as described above. Next, the configuration of the NOT circuit optical element 14 of FIG. 3 will be described. Similarly to the AND circuit optical element 13, the NOT circuit optical element 14 has two incident light incidence waveguides 4a and 4b which are connected to one non-linear waveguide 6b via a confluence point B, and thus the non-linear An analyzer 9b is provided on the exit end side of the waveguide 6b.
Is provided.

The incident light incident waveguides 4a and 4b in the NOT circuit optical element 14 are configured similarly to the incident light incident waveguides 3a and 3b in the AND circuit optical element 13, respectively. Is a probe terminal connected to the incident end side of the incident light incident waveguide 4a,
An optical pulse train synchronized with the operation clock of the circuit is input to this terminal in the case of digital operation, and CW (continuous) light is input as probe light in the case of analog operation. This probe light is transmitted through the nonlinear waveguide 6b.
The incident polarized light is linearly polarized in the direction of the fast axis (X axis in FIG. 6), and its light intensity is the same as the input light.

The non-linear waveguide 6b in the NOT circuit optical element 14 is constructed in substantially the same manner as the non-linear waveguide 6a in the AND circuit optical element 13, and the non-linear refractive index of the non-linear waveguide 6b in the NOT circuit optical element 14 is set. And length L ₂
Is adjusted such that when only the probe light is incident, the phase change when the probe light propagates through the nonlinear waveguide 6b is 180 degrees at the exit end.

Unlike the analyzer 9a in the AND circuit optical element 13, the analyzer 9b is formed such that its light transmission direction is parallel to the polarization axis of linearly polarized light that has undergone a phase change of 180 degrees. As a result, the analyzer 9b serves as an output selection unit that selectively outputs the propagation light (propagation light when only the probe light is propagated) whose phase is changed by 180 degrees among the propagation light of the nonlinear waveguide 6b. It is supposed to work.

Similar to the non-linear waveguide of the AND circuit optical element 14, electrodes are provided on both sides of the non-linear waveguide 6b of the NOT circuit optical element 14 (not shown), and the same non-linear polarization rotation is performed. The amount can be finely adjusted, and an optical waveguide (not shown) for propagating reflected light reflected by the analyzer is formed at the connection point between the nonlinear waveguide 6b and the analyzer 9b. .

In this embodiment, the AND circuit optical element 13
Of the incident light incident waveguides 3a and 3b at the output end (the input / output end C of the connection between the AND circuit optical element 13 and the NOT circuit optical element 14)
A reverse optical rotatory substance for rotating the optical rotatory substance in the opposite direction by the same amount as the optical rotatory substance and an attenuator element (not shown) for attenuating the output light from the AND circuit optical element 13 by 3 dB are provided.

The present embodiment is constructed as described above,
Next, the operation will be described. For example, when the light linearly polarized in the X-axis direction (X-axis direction of the nonlinear waveguide) at the incident end is input from either one of the incident light incident waveguides 3a and 3b of the AND circuit optical element 13. This light becomes linearly polarized light whose polarization plane is deviated by an angle other than 90 degrees from the X-axis direction due to the optical rotatory substance provided in the incident light incident waveguide. In other words, for example, if the plane of polarization of the input light is displaced in the Xa direction in FIG. 6, this linearly polarized light is XaZ.
It becomes linearly polarized light that advances in the Z-axis direction along a plane.

When this light enters the nonlinear waveguide 6a at the confluence A, nonlinear polarization rotation is performed by the nonlinear waveguide 6a to rotate the polarized light, and linearly polarized light → elliptically polarized light → circularly polarized light → elliptically polarized light. → Linearly polarized light → Elliptical polarized light → Circularly polarized light → Polarization changes. In such polarization rotation, the phase change thereof changes according to the relationship shown in the equation (1), and the length of the nonlinear waveguide 6a is changed to the incident light incident waveguide 3a, as in the present embodiment. It is adjusted so that the phase change when the incident polarized light propagates through the nonlinear waveguide 6a changes by 180 degrees at the exit end of the nonlinear waveguide 6a when the incident polarized light enters from only one of 3b. The linearly polarized light incident on the nonlinear waveguide 6a is changed to a linearly polarized light by a phase change of 180 degrees.
It becomes elliptically polarized light → circularly polarized light → elliptically polarized light → linearly polarized light.

On the other hand, when input light is made incident from both the incident light incident waveguides 3a and 3b, the polarization planes of these input lights are 90 degrees from the X-axis direction due to the optical rotatory substance of the incident light incident waveguides 3a and 3b. The linearly polarized light is shifted by the same angle other than degrees, for example, in the Xa direction, is combined at the confluence A, and is incident on the nonlinear waveguide 6a. Since the electric field intensity of this light is twice as high as that when the input light is incident only from one of the incident light incident waveguides, it is calculated from the above formula (1) that the light propagates through the nonlinear waveguide 6a. The phase change of wave light becomes 360 degrees, and becomes linear polarization → elliptical polarization → circular polarization → elliptical polarization → linear polarization → elliptical polarization → circular polarization → elliptical polarization → linear polarization.

The polarized light after undergoing the phase change of 180 degrees and the polarized light after undergoing the phase change of 360 degrees are both linearly polarized light, and the linearly polarized light is orthogonal to each other. In the example, since only the light that has undergone the phase change of 360 degrees is output from the analyzer 9a, as shown in Table 1 above, at the input / output terminal C, there is no input or only one input. In the case, the output is 0, and in the case of 2 inputs, the output is 1. Then, this output light is rotatively rotated in the opposite direction by the same amount as that rotated by the optical rotatory substance, by the optical rotatory substance provided at the exit end of the nonlinear waveguide 6a, and
An attenuator element provided at the exit end of the nonlinear waveguide 6a gives 3 dB of attenuation, outputs light of the same power as the input light, and makes it incident on the incident light incident waveguide 4b of the NOT circuit optical element 14. .

Incident light incident waveguide 4 of NOT circuit optical element 14
When the input light (the output light from the AND circuit optical element 13) is incident on b, the polarization plane of this light is shifted from the X-axis direction by the optical rotatory substance of the incident light incident waveguide 4b to the nonlinear waveguide 6b. It is incident. In the NOT circuit optical element 14, even when the probe light is incident from the incident light incident waveguide 4a, the polarization plane of the probe light is similarly shifted by the optical rotatory substance from the X-axis direction, and the nonlinear waveguide 6b. Incident on. When only the probe light is incident on the NOT circuit optical element 14, the probe light is emitted from the nonlinear waveguide 6b.
When the probe light and the input light are both incident (when the output from the AND circuit optical element 13 is performed)
Of the input light and the probe light are combined, and the combined light propagates through the nonlinear waveguide 6b and undergoes a phase change of 360 degrees to become linearly polarized light.

Since the analyzer 9b provided in the NOT circuit optical element 14 is configured to output linearly polarized light that has undergone a phase change of 180 degrees, as shown in Table 2 above, When only the probe light is incident on the NOT circuit optical element 14 (when the input is 0 in Table 2), light is output from the analyzer 9b, while both the probe light and the input light are incident on the NOT circuit optical element 14. When incident (input 1 in Table 2), no output is performed.

Therefore, in this embodiment, as shown in Table 3, the incident light incident waveguides 3a and 3b of the AND circuit optical element 13 are provided.
Light is output from the output end 18 of the optical logic circuit except when the input light is input from both of them, and the same optical control operation as the electrical control operation of the electrical NAND circuit is performed. Be seen.

[0045]

[Table 3]

According to the present embodiment, as described above, the incident light incident waveguides 3a, 3b, 4a, 4b are provided with optical rotatory substances as polarization plane adjusting means, respectively, so that the polarization plane of the incident polarized light is nonlinear. The waveguides 6a, 6b are made to enter the nonlinear waveguides 6a, 6b by shifting from the fast axis by the same angle other than 90 degrees,
The nonlinear refractive index and the length of each of the nonlinear waveguides 6a and 6b are formed so that the phase polarization of the light propagating through the nonlinear waveguides 6a and 6b can be adjusted, and an analyzer 9a provided at the emission end thereof,
9b selectively outputs only the propagating light whose phase is changed at a predetermined angle, thereby performing an optical control operation similarly to an AND circuit which is an electric logic element.
It is possible to form the circuit optical element 13 and the NOT circuit optical element 14 that can control the light similarly to the electric NOT circuit. Then, the AND circuit optical element 13 and the NOT circuit optical element 14 can be combined and connected to form an optical logic circuit that can perform a light control operation like an electric NAND circuit.

Further, according to the present embodiment, all the components such as the optical waveguide forming the optical logic circuit are formed on the quartz base, and the nonlinear refractive index of the nonlinear waveguides 6a and 6b should be increased. As a result, the length of the nonlinear waveguides 6a and 6b can be shortened, and a very small circuit can be obtained.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in the above embodiment, the incident light incident waveguides 3a, 3b, 4a, 4b are used.
Although the polarization plane adjusting means is formed by doping the optical polarization substance in the above, the polarization plane adjusting means is not always constituted by the optical rotation substance, and for example, the polarization vector of the incident polarized light is caused by the polarizer or the Faraday effect. May be rotated to shift the plane of polarization of the incident polarized light by the same angle other than 90 degrees from the fast axis or the slow axis of the nonlinear waveguide.

Further, in the above-mentioned embodiment, the polarization plane of the incident polarized light incident from each incident light incident waveguide is shifted by the same angle other than 90 degrees from the fast axis of the nonlinear waveguide by the optical rotatory substance. The polarization plane adjusting means such as an optical rotatory substance may shift the polarization plane of the incident light from the slow axis of the nonlinear waveguides 6a and 6b by the same angle other than 90 degrees.

Further, in the above embodiment, the nonlinear waveguide 6
Electrodes 8 are provided on both sides of a and 6b to provide nonlinear waveguides 6a and 6a.
Although the amount of nonlinear polarization rotation is finely adjusted by b, the electrode 8 can be omitted if the amount of nonlinear polarization rotation can be optimized by the nonlinear waveguides 6a and 6b.

Further, in the above embodiment, one NOT circuit optical element 14 is connected to the emission end side of one AND circuit optical element 13 to form an optical logic circuit for performing optical control like a NAND circuit. AND circuit optical element 13 and NOT circuit optical element 14
It is possible to form an optical logic circuit, a flip-flop, and the like that perform various optical operation control by connecting various combinations of.

For example, FIG. 5 shows an example in which three NOT circuit optical elements 14 and one AND circuit optical element 13 are combined and connected to form an OR circuit type optical logic circuit.
According to this circuit, the AND circuit optical element 13 and each NOT
When the circuit light element 14 performs the same operation as that of the above-described embodiment, as shown in Table 4, the output / input terminals D, D of FIG.
The input and output at E and F are determined by the presence or absence of input of the input light a and b. In this OR circuit type optical logic circuit, when at least one side of the input lights a and b is input, the output from the output terminal 18 is performed, and the optical operation is performed similarly to the electric OR circuit. Control is performed.

[0053]

[Table 4]

Furthermore, if an amplification section such as an amplifier capable of compensating for the decrease in light intensity caused when the waveguide is branched can be formed in the branching section of the waveguide, the optical logic including the waveguide branching section can be formed. Devices and optical logic circuits can also be formed.

[0055]

According to the present invention, the polarization plane of the incident polarized light incident on the nonlinear waveguide from the incident light incident waveguide is set to other than 90 degrees from the fast axis or the slow axis of the nonlinear waveguide by the polarization plane adjusting means. By making the incident light shift by the same angle, the polarization plane of the incident polarized light is rotated when the incident polarized light propagates, and the phase change of the polarization plane rotation of the propagated light depends on the light intensity of the propagated light. By utilizing this, it is possible to determine the phase change of the propagating light propagating through the nonlinear waveguide at different angles depending on whether the incident polarized light is incident from only one incident light incident waveguide or both incident light. .

By adjusting the nonlinear refractive index and the length of the nonlinear waveguide, for example, when the incident polarized light is incident from only one incident light incident waveguide, the propagation light of the nonlinear waveguide is By setting the phase change to a predetermined angle at the exit end and selectively outputting only the propagation light whose phase is changed at the predetermined angle among the propagation lights of the nonlinear waveguide, two incident light beams can be obtained. The presence or absence of output can be logically selected depending on whether the incident polarized light is incident from only one of the incident waveguides, the incident polarized light is incident from both of them, or the incident polarized light is not incident. It becomes possible to decide. Therefore, by inputting and outputting light in this way, it is possible to construct an optical logic element that can perform the optical control operation by the light itself as in the electrical control operation by the electrical logic element.

Further, according to the present invention, this optical logic element can determine the presence / absence of the output only by the presence / absence of the incident light while keeping the light intensity of the incident polarized light incident on the incident light incident waveguide constant. It is possible, because it does not require any electrical input / output, and the light is controlled by the light itself, so that it is possible to exhibit an ultra-high-speed processing speed. It can be applied to a future optical computer expected as an information processing device and can exert a very excellent effect.

Further, according to the present invention, the optical logic element is
It is configured by using an optical waveguide such as an incident light incident waveguide or a nonlinear waveguide. For example, these optical waveguides are formed on a silica-based substrate, and output selecting means provided on the emission end side of the nonlinear waveguide. Since it is also possible to form the above elements on a quartz-based substrate, it is possible to make the device very small.

As described above, an optical logic circuit formed by using an excellent optical logic element which is small in size and has a very high processing speed makes use of an excellent effect of the optical logic element. A logic circuit can be provided, and an excellent optical logic circuit that can perform various optical control operations depending on how to combine and connect optical logic elements can be provided.

[Brief description of drawings]

FIG. 1 is a main part configuration diagram showing an embodiment of an optical logic circuit using an optical logic element according to the present invention.

FIG. 2 is a configuration diagram showing an AND circuit optical element forming the optical logic circuit of the above embodiment.

FIG. 3 is a configuration diagram showing a NOT circuit optical element forming the optical logic circuit of the embodiment.

FIG. 4 is an explanatory diagram showing a state in which an electrode 8 is formed on an AND circuit optical element used in the optical logic circuit of the above embodiment.

FIG. 5 is a main part configuration diagram showing another embodiment of an optical logic circuit using an optical logic element according to the present invention.

FIG. 6 is an explanatory diagram of an optical axis of a nonlinear waveguide and a polarization component axis formed in the nonlinear waveguide.

[Explanation of symbols]

 3a, 3b, 4a, 4b Incident light incident waveguide 6a, 6b Non-linear waveguide 9a, 9b Analyzer 13 AND circuit optical element 14 NOT circuit optical element

Claims (4)

[Claims] 1. Two incident light incident waveguides are merged and connected to one non-linear waveguide that performs non-linear polarization rotation of light via a confluence point, and the non-linear waveguide is connected to the non-linear waveguide. Due to the polarization dispersion of, the slow axis, which is the polarization component axis having a slow propagation speed of light, and the fast axis having a faster propagation speed of light than the slow axis are orthogonal to each other, and The two incident light incident waveguides are formed so as to be orthogonal to the axis, and the polarization plane of the incident polarized light incident on the nonlinear waveguide from each of the incident light incident waveguides is set to the fast axis of the nonlinear waveguide. Alternatively, an optical logic element is provided with polarization plane adjusting means for shifting from the slow axis by the same angle other than 90 degrees. 2. The nonlinear refractive index and the length of the nonlinear waveguide are
When incident polarized light enters from only one of the two incident light incident waveguides, the phase change when the incident polarized light propagates through the nonlinear waveguide changes at the exit end at a predetermined angle. The optical logic element according to claim 1, wherein the optical logic element is adjusted as follows. 3. An output selection means is provided on the exit end side of the nonlinear waveguide for selectively outputting only the propagated light of the nonlinear waveguide whose phase is changed at a predetermined angle. The optical logic device according to claim 1 or 2, which is characterized in that. 4. An optical logic circuit comprising a plurality of optical logic elements according to claim 1 connected in combination.