JP5721427B2 - Optical switch and logic gate using optical switch - Google Patents

Description

(Refer to related applications)
Reference is made to the following related applications, the disclosures of all of which are incorporated herein by reference.

Applied on April 12, 2007 US patent application Ser. No. 11/734747, entitled “
U.S. Patent Application No. 11/7350 entitled "LIGHT ACTIVE OPTICAL SWITCH THEN INCLUDES A PIEZOELECTRIC ELEMENT AND A CONDUCTIVE LAYER", filed April 12, 2007,
US Provisional Patent Application No. 60/91469 entitled “LOGIC GATES FOR OPTICAL SIGNALS” filed on April 12, 2007, and continuation of US Pat. No. 7,283,698, 2007 US patent application Ser. No. 11 / 974,443, filed Oct. 15.

The priority of the following application is claimed here under 37 CFR 1.78 (a) (1), (a) (4) and (5) (i).
Applied on April 12, 2007 US patent application Ser. No. 11/734747, entitled “
U.S. Patent Application No. 11/7350 entitled "LIGHT ACTIVE OPTICAL SWITCH THEN INCLUDES A PIEZOELECTRIC ELEMENT AND A CONDUCTIVE LAYER", filed April 12, 2007, And US Provisional Patent Application No. 60/911469, filed April 12, 2007, entitled “LOGIC GATES FOR OPTICAL SIGNALS”.

  The present invention generally relates to light activated switches and logic gates.

U.S. Pat. Nos. 7,072,536 and 7,283,698, inventors of the present invention by Dr. Gary Neal Povey, the disclosures of which are incorporated herein by reference, are listed below. Along with the publications whose disclosure is also incorporated herein by reference, the latest state of the art,
U.S. Patent Nos. 6,594,411, 4,961,618, 5,414,789, 2,936,380, 3,680,080, 3, 965,388, 3,995,311, 4,023,887, 4,128,300, 4,262,992, 4,689,793, 4,764,889, 4,978,842, 5,078,464, 5,109,156, 5,146,078, 5,168 382, 6,005,791, 6,609,840, 7,263,262, 3,987,310, 4,053,794, 6,757,459, 6,804,427, 6,320,994, 6,4 No. 7,333, No. 6,178,033, No. 5,425,115, No. 6,075,512, No. 6,697,548, No. 6,594,411, 5,703,975, 6,320,994, 5,134,946, 7,283,695, 5,414,789, 4,961 , 618, 2,936,380, 3,680,080, 3,965,388, 3,995,311, 4,023,887, 4,128,300, 3,995,311, 4,023,887, 4,128,300, 4,262,992, 4,689, 793, 4,764,889, 4,961,618, 4,978,842, 5,078,464, 5,109,156, 5,146,078, 5,168,382, 6,005,791, 6,609, No. 840, No. 7,263,262, No. 6,151,428, No. 5,999,284, No. 5,315,422, No. 5,144,375, No. 5,101,456, 4,932,739, 4,701,030, 4,630,898, 3,987,310 and 4,053,794, and US Patent Application Publication Nos. 2005/0129351, 2006/0045407, 2004/0091201 and 2004/0037708, and Alexei Grigoriev et al., “Subnanosecond piezoe”. ectric x-ray switch (sub-nanosecond piezoelectric x- line switch) "(Applied Physics Letters89,021109, 2006 years)
It seems to represent.

  It is an object of the present invention to provide improved optical switches, logic gates and logic functions.

Thus, according to a preferred embodiment of the present invention,
An optical path having a variable cross-sectional area;
An activated photoresponsive piezoelectric element coupled to the light path, the activated photoresponsive piezoelectric element operating to change its shape in response to incident activated light;
An optical switch comprising a conductive element operatively coupled to the piezoelectric element for improving the activation light response of the piezoelectric element, wherein the activation light response type piezoelectric element is coupled to the optical path, An optical switch is provided in which the responsive piezoelectric element operates to sufficiently change the variable cross-sectional area of the optical path by changing the shape of the piezoelectric element and to control the passage of light along the optical path.

  In the optical path, the piezoelectric element, and the conductive element, when the activation light within the threshold level of the first range is incident on the piezoelectric element, the light of the wavelength in the first range is blocked from passing through the optical path. When the activation light within the threshold level of the second range that is outside the range of the threshold level of the first incident on the piezoelectric element, the light of the wavelength in the first range is allowed to pass through the optical path and operates. It is preferable to do.

According to a preferred embodiment of the present invention, the conductive element comprises a layer of conductive material extending along the surface of the piezoelectric element.
The piezoelectric element preferably comprises at least two layers of piezoelectric material having different piezoelectric properties.

According to a preferred embodiment of the invention, the at least two layers of piezoelectric material have different crystal orientations.
The conductive element is preferably arranged between the two layers of the piezoelectric element.

  According to a preferred embodiment of the present invention, an optical coupler is provided that operates to guide the activation light and the signal light to the optical path, and at least one characteristic of the activation light passes through the path to the signal light. Control whether or not

Furthermore, according to a preferred embodiment of the present invention,
An optical path having a variable cross-sectional area;
An activated light responsive piezoelectric element coupled to an optical path, wherein the activated light responsive piezoelectric element operates to change its shape in response to incident activated light. The activated light-responsive piezoelectric element comprises at least two layers of piezoelectric material having different piezoelectric properties, the piezoelectric element is associated with the light path, and the variable cross-sectional area of the light path is sufficiently increased by changing the shape of the piezoelectric element An optical switch is provided that varies and operates to control the passage of light along the optical path.

  When the activation light within the first range threshold level is incident on the piezoelectric element, the optical path and the piezoelectric element are blocked from passing through the optical path of light having a wavelength in the first range. When the activation light within the threshold level of the second range that is outside the range is incident on the piezoelectric element, the light of the wavelength in the first range may be allowed to pass through the optical path and operate. preferable.

According to a preferred embodiment of the present invention, at least one having at least one of a knot function, an AND function, an OR function, a NAND function, and a NOR function, comprising at least one optical switch driven by light. A logic gate with one gate is provided, and at least one optical switch is
A signal light path having a variable cross-sectional area;
An activation light responsive piezoelectric element coupled to the light path, the activation light responsive piezoelectric element operating to change its shape in response to incident activation light The light-responsive piezoelectric element is associated with the light path, and the activated light-responsive piezoelectric element sufficiently changes the variable cross-sectional area of light by changing the shape of the piezoelectric element, and controls the passage of signal light along the light path. To behave.

  The logic gate is an optical path that supplies activation light to at least one optical switch, transmits digital information to at least one optical switch, and transmits signal light that transmits digital information from at least one optical switch. It is preferable to provide a light path for carrying.

According to a preferred embodiment of the present invention, the signal light has a wavelength longer than that of the activation light.
The signal light preferably has a wavelength that is approximately twice the wavelength of the activation light.

According to a preferred embodiment of the present invention, the signal light has a wavelength of 1500 nm and the activation light has a wavelength of about 750 nm.
According to a preferred embodiment of the present invention, there is further provided a logic gate providing a knot function, wherein at least one optical switch comprises a single optical switch, and the signal light is about 2 of the wavelength of the activation light. It has a double wavelength.

According to a preferred embodiment of the present invention, a logic gate providing an AND function is further provided, wherein at least one optical switch comprises a single optical switch, and the signal light is longer than the wavelength of the activation light. The logic gate further has a wavelength,
First and second logic inputs for receiving signal light;
A first light path for receiving a first portion of the signal light received at the first logic input;
A second optical path for receiving a second portion of the signal light received at the first logic input;
A third light path for receiving a first portion of the signal light received at the second logic input;
A fourth optical path for receiving a second portion of the signal light received at the second logic input;
A first wavelength corrector that operates to shorten the wavelength of light along the second optical path to the wavelength of the activation light;
A second wavelength modifier that operates to shorten the wavelength of light along the fourth optical path to the wavelength of the activation light;
A first phase matcher that operates to match the phase of the light along the second optical path to the phase of the activation light;
A second phase matcher that matches the phase of the light along the fourth optical path to the activation light;
Light that is shortened and phase matched along the second optical path and light that operates to cause the wavelength shortened and phase matched light along the fourth optical path to be 180 degrees out of phase with each other. A phase shifter,
The light along the first and third optical paths is supplied as signal light input to the optical switch,
Light whose wavelength is shortened and phase-matched along the second and fourth optical paths is supplied to the optical switch as activation light together with additional activation light.

According to a preferred embodiment of the present invention, a logic gate providing a NAND function is further provided, wherein the first optical switch includes a first optical switch and a second optical switch, and the signal light is active. Having a wavelength longer than the wavelength of the activating light, the logic gate further comprises:
First and second logic inputs for receiving signal light inputs;
A first wavelength corrector that operates to shorten the wavelength of the signal light of the first input to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of the signal light of the second input to the wavelength of the activation light;
A third wavelength corrector that operates to shorten the wavelength of the signal light from the first optical switch;
A first light path for supplying a portion of the light from the first wavelength corrector to the first light absorber;
A second optical path for supplying a portion of the light from the first wavelength corrector to the first optical switch;
A third light path for supplying a portion of the light from the second wavelength modifier to the second light absorber;
A fourth optical path for supplying a portion of the light from the second wavelength modifier to the first optical switch;
A fifth optical path for supplying signal light from the first optical switch to the third wavelength modifier;
A sixth optical path for supplying the optical wavelength correction light from the third wavelength corrector to the second optical switch as activation light.

According to a preferred embodiment of the present invention, a logic gate providing an OR function is further provided, wherein at least one optical switch comprises a single optical switch, and the signal light is longer than the wavelength of the activation light. The logic gate further has a wavelength,
First and second logic inputs for receiving signal light inputs;
A first wavelength corrector that operates to shorten the wavelength of light along the first light input to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of light along the second light input to the wavelength of the activation light;
A first phase matcher that operates to match the phase of the wavelength corrected light from the first wavelength corrector to the phase of the drive light;
A second phase matcher that operates to match the phase of the light from the second wavelength corrector to the phase of the drive light;
A first optical path for supplying a portion of the light from the first phase matcher to the first light absorber;
A second optical path for supplying a portion of the light from the second phase matcher to the second optical absorber;
A first optical phase shifter;
A second optical phase shifter;
A third light that supplies a portion of the light from the first phase matcher to the first optical phase shifter, thereby causing the light from the first phase matcher to be out of phase with respect to the activation light. A passage,
Supplying a portion of the light from the second phase matcher to the second optical phase shifter, thereby causing the light from the first phase matcher to be out of phase with respect to the supply activation light; A light passage,
A fifth optical path for supplying light from the first optical phase shifter to the optical switch;
A sixth optical path for supplying light from the second optical phase shifter to the optical switch, and the optical switch receives the activation light and the signal light from the fifth and sixth optical paths.

According to a preferred embodiment of the present invention, there is further provided a logic gate that provides an OR function, wherein at least one optical switch includes first and second optical switches, and the signal light is a wavelength of activation light. The logic gate further has a longer wavelength than
First and second logic inputs for receiving signal light inputs;
A first wavelength corrector that operates to shorten the wavelength of light along the first light input to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of light along the second light input to the wavelength of the activation light;
First and second optical paths for supplying wavelength corrected light from the first and second wavelength correctors;
An optical output limiter for receiving light from a first wavelength corrector and a second wavelength corrector via first and second optical paths, respectively, the first wavelength corrector and the second wavelength corrector An optical output limiter that operates to maintain the optical output from the predetermined optical output level;
A third optical path for supplying optical output limiting light from the optical output limiter to the first optical switch;
A third wavelength corrector for receiving signal light from the first optical switch, the third wavelength corrector operating to reduce the wavelength of the light to the wavelength of the activation light;
And a fourth optical path for supplying light from the third wavelength corrector to the second optical switch.

According to a preferred embodiment of the present invention, a logic gate providing an OR function is further provided, wherein at least one optical switch comprises a single optical switch, and the signal light is longer than the wavelength of the activation light. The logic gate further has a wavelength,
First and second logic inputs for receiving signal light;
A first light path for receiving a first portion of the signal light received at the first logic input;
A second optical path for receiving a second portion of the signal light received at the first logic input;
A third light path for receiving a first portion of the signal light received at the second logic input;
A fourth optical path for receiving a second portion of the signal light received at the second logic input;
A first wavelength corrector that operates to shorten the wavelength of light along the second optical path to the wavelength of the activation light;
A second wavelength modifier that operates to shorten the wavelength of light along the fourth optical path to the wavelength of the activation light;
An optical phase shifter that operates to cause the wavelength corrected light from the first wavelength corrector to be 180 degrees out of phase with respect to the light from the second wavelength corrector. Light is received from the first and third optical paths, the second wavelength modifier and the optical phase shifter.

Further, a logic gate is provided in which at least one optical switch is configured as described above and the logic function uses one or more logic gates as described above.
Also, according to a preferred embodiment of the present invention,
A signal channel configured to guide signal light;
A piezoelectric element adjacent to the signal channel;
A conductive layer adjacent to the piezoelectric element, and applying an activation light to the piezoelectric element controls the passage of the signal light through the signal channel, and the electric field applied to the piezoelectric element conducts in response to the activation light. A layer-enhanced optical switch is provided.

The conductive layer is preferably attached to the surface of the piezoelectric element.
According to a preferred embodiment of the present invention, activation light is applied to the piezoelectric element, and the shape of the piezoelectric element is changed so that the signal light cannot pass through the signal channel.

The signal channel preferably comprises a chamber filled with a compressible material.
The piezoelectric element preferably forms part of the chamber.
According to a preferred embodiment of the present invention, the piezoelectric element comprises at least two layers having different piezoelectric properties.

The conductive layer is preferably deposited between the two layers of the piezoelectric element.
According to a preferred embodiment of the present invention, there is further provided a method for operating an optical switch comprising:
Applying signal light to an optical switch comprising a piezoelectric element and at least one conductive layer adjacent to the piezoelectric element;
Applying an activation light to the piezoelectric element to change the state of the optical switch, and providing a method in which the electric field applied to the piezoelectric element is enhanced by the conductive layer in response to the applied activation light Is done.

Preferably, the step of applying the activation light to the piezoelectric element changes the shape of the piezoelectric element so that the signal light cannot pass through the optical switch.
The step of applying the activation light includes applying two optical signals out of phase to the piezoelectric element, removing one of these optical signals, and leaving the other optical signal as the activation light. Preferably steps are included.

Furthermore, a method for operating an optical switch, comprising:
Applying signal light to a signal channel adjacent to a piezoelectric element adjacent to at least one conductive layer;
Applying an activation light to the piezoelectric element to change the shape of the piezoelectric element so as to prevent the signal light from passing through the signal channel, and an electric field applied to the piezoelectric element is applied to the activation light. In response to the method, a method enhanced by the conductive layer is provided.

Furthermore,
A signal channel configured to guide signal light;
A piezoelectric element adjacent to the signal channel;
A conductive layer adjacent to the piezoelectric element;
Means for applying activation light to the piezoelectric element and changing the shape of the piezoelectric element so that signal light is prevented from passing through the signal channel, and an electric field applied to the piezoelectric element is applied to the activation light. In response, an optical switch is provided that is enhanced by the conductive layer.

Furthermore, a method for operating an optical switch, comprising:
Applying signal light to an optical switch comprising a piezoelectric element, the piezoelectric element comprising at least two layers of piezoelectric material having different piezoelectric properties;
Applying activation light to the piezoelectric element to change the state of the optical switch.

Preferably, the step of applying the activation light to the piezoelectric element changes the shape of the piezoelectric element so that the signal light cannot pass through the optical switch.
It is preferable to change the dimensions of the signal channel of the optical switch by changing the shape of the piezoelectric element.

  According to a preferred embodiment of the present invention, the step of applying the activating light includes applying two optical signals out of phase to the piezoelectric element, removing one of these optical signals, The step of leaving the other optical signal as activation light is included.

According to a preferred embodiment of the present invention, the electric field applied to the piezoelectric element is enhanced by the conductive layer adjacent to the piezoelectric element in response to the applied activation light.
Also,
A signal channel configured to guide signal light;
A piezoelectric element adjacent to the signal channel, the piezoelectric element comprising at least two layers of piezoelectric material having different piezoelectric properties, and applying an activation light to the piezoelectric element to transmit the signal light through the signal channel An optical switch with controlled passage is provided.

It is preferable to change the shape of the piezoelectric element by applying activation light to the piezoelectric element so that the signal light cannot pass through the signal channel.
Also, a method for operating an optical switch,
Applying signal light to a signal channel, the signal channel adjacent to a piezoelectric element having at least two layers of piezoelectric material having different piezoelectric properties;
Applying activation light to the piezoelectric element to change the shape of the piezoelectric element such that signal light is prevented from passing through the signal channel.

Furthermore,
A signal channel configured to guide signal light;
A piezoelectric element adjacent to the signal channel, the piezoelectric element comprising at least two different layers having different piezoelectric properties;
An optical switch is provided that includes means for applying activation light to the piezoelectric element to change the shape of the piezoelectric element so that the signal light is prevented from passing through the signal channel.

  The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which:

FIG. 2 shows an optical switch controlled by activation light, comprising a signal channel and a piezoelectric element. FIG. 1B is a diagram showing the piezoelectric element of FIG. 1A in an activated state obtained by applying activation light to the piezoelectric element. FIG. 2 is a cross-sectional view of the signal channel and piezoelectric element of FIG. 1A taken along line IIA-IIA of FIG. 1A when the piezoelectric element is in an inactive state. FIG. 2 is a cross-sectional view of the signal channel and piezoelectric element of FIG. 1B taken along line IIB-IIB of FIG. 1B when the piezoelectric element is in an active state. FIG. 6 is a graph showing signal attenuation versus signal channel dimensions. FIG. FIG. 3 shows a technique for changing the state of an optical switch including applying activation light having a wavelength shorter than the wavelength of signal light. FIG. 3 shows a technique for changing the state of an optical switch including applying activation light having a wavelength shorter than the wavelength of signal light. Applying activation light to the piezoelectric element provides two optical signals that are out of phase with each other, then removing one of these optical signals and leaving the other optical signal as the activation light. FIG. 6 illustrates a technique for changing the state of an optical switch including. Applying activation light to the piezoelectric element provides two optical signals that are out of phase with each other, then removing one of these optical signals and leaving the other optical signal as the activation light. FIG. 6 illustrates a technique for changing the state of an optical switch including. FIG. 2 is a diagram illustrating one embodiment of a light activated optical switch including a signal channel, a piezoelectric element, and a conductive layer adjacent to the piezoelectric element. FIG. 6B is a diagram showing the piezoelectric element in FIG. 6A in an active state obtained by applying activation light to the piezoelectric element. It is a figure which shows the effect | action of the electric field of light with respect to the electron of a conductive layer. FIG. 8 is a diagram illustrating an optical switch system including the photoactive optical switch described above with reference to FIGS. 1A to 7. FIG. 2 illustrates one embodiment of an optical switch and an optical coupler used to couple signal light and activation light to the same signal channel. FIG. 4 illustrates one embodiment of a piezoelectric element having three or more layers of piezoelectric material with different piezoelectric properties. It is a figure which shows one Embodiment of the photoactive optical switch provided with the conductive layer pinched | interposed between two layers of a piezoelectric element. It is a figure which shows one Embodiment of the photoactive optical switch provided with the some conductive layer pinched | interposed between the multilayer piezoelectric elements. FIG. 2 is a diagram illustrating one embodiment of a light activated optical switch with multilayer piezoelectric elements and conductive layers on two different sides of a signal channel. FIG. 2 is a diagram illustrating one embodiment of a light activated optical switch that includes a multilayer piezoelectric element and a conductive layer on each of two surfaces of a signal channel. FIG. 2 illustrates one embodiment of a light activated optical switch that includes a signal channel and a piezoelectric element, with a portion of the signal channel filled with a compressible material. FIG. 11B shows the piezoelectric element of FIG. 11A in an active state obtained by applying activation light to the piezoelectric element. A photoactive optical switch comprising a signal channel, a piezoelectric element, and a conductive layer adjacent to the piezoelectric element, wherein the signal channel is an optical fiber, and the piezoelectric element and the conductive layer are formed in a band shape around the circumference of the optical fiber. It is a figure which shows one embodiment of. FIG. 12B shows the piezoelectric element of FIG. 12A in an active state obtained by applying activation light to the piezoelectric element. FIG. 2 is a diagram showing an embodiment of a light activated optical switch that includes a signal channel, a transparent piezoelectric element, and a conductive layer adjacent to the piezoelectric element, and includes a piezoelectric element with a transparent signal channel. FIG. 13B is a diagram illustrating the piezoelectric element of FIG. 13A in an active state obtained by applying activation light to the piezoelectric element. FIG. 6 is a simplified diagram of an optical switch according to another preferred embodiment of the present invention. FIG. 6 is a simplified diagram of an optical switch according to another preferred embodiment of the present invention. 14B is a cross-sectional view of the signal channel and piezoelectric element of FIG. 14A taken along line XVA-XVA of FIG. 14A. 14B is a cross-sectional view of the signal channel and piezoelectric element of FIG. 14B taken along line XVB-XVB of FIG. 14B. FIG. 6 is a simplified diagram of an optical switch according to still another preferred embodiment of the present invention. FIG. 6 is a simplified diagram of an optical switch according to still another preferred embodiment of the present invention. FIG. 16B is a cross-sectional view of the signal channel and piezoelectric element of FIG. 16A taken along line XVIIA-XVIIA of FIG. 16A. 16D is a cross-sectional view of the signal channel and piezoelectric element of FIG. 16B taken along line XVIIB-XVIIB of FIG. 16B. FIG. 6 is a simplified diagram of an optical switch according to still another preferred embodiment of the present invention. FIG. 6 is a simplified diagram of an optical switch according to still another preferred embodiment of the present invention. FIG. 18B is a cross-sectional view of the signal channel and piezoelectric element of FIG. 18A taken along line XIXA-XIXA of FIG. 18A. FIG. 19 is a cross-sectional view of the signal channel and piezoelectric element of FIG. 18B taken along line XIXB-XIXB of FIG. 18B. 3 is a schematic diagram of a logic knot gate. It is the schematic of the logic AND gate which uses an optical switch. FIG. 3 is a second schematic diagram of a logical AND gate using an optical switch. FIG. 2 is a schematic diagram of a logical OR gate using an optical switch and a phase matching device. It is the schematic of the logic OR gate using an optical switch and an optical output limiter. It is the schematic of the logic OR gate using an optical switch.

  Light-driven optical switches are used to construct AND logic gates, OR logic gates, and NOR logic gates. The optical signals input to these logic gates are processed so that the output of these logic gates meets the specifications required for each type of gate. All of the optical signals are used to operate these logic gates and use an optically driven optical switch, so no external batteries are required, and therefore these logic gates are sized to match the semiconductor logic design dimensions. Can have.

  Computers can be made to work with optical signals instead of electrical signals. Transistor-based logic gate transistors switch in 10E-9 seconds, which limits the speed of transistor-based logic gates. The light can travel 3 microns in 10E-14 seconds. Logic gates based on light-driven switches are much faster than transistor-based logic gates.

  The optical switch includes a signal channel and a piezoelectric element adjacent to the signal channel. The piezoelectric element changes its shape in response to the activation light, and therefore the piezoelectric element is configured with respect to the signal channel such that its shape changes as the shape changes. For example, when the shape of the piezoelectric element changes, the dimensions of the signal channel become sufficiently short so that signal light can no longer pass through the signal channel. Using this phenomenon, the state of the optical switch is controlled by controlling the activation light applied to the piezoelectric element. In one embodiment, the optical switch allows signal light to pass through the signal channel when no activation light is applied to the piezoelectric element, and when the activation light is applied to the piezoelectric element, the signal light signal Channel passage is blocked. Since the shape of the piezoelectric element determines whether light passes through the signal channel, the function of the optical switch depends on the ability of the piezoelectric element to change its shape.

  According to one embodiment of the invention, the piezoelectric element has at least two layers of piezoelectric material, each layer having different piezoelectric properties. The piezoelectric properties of these layers are selected so that the performance of the piezoelectric element is improved and ultimately the performance of the optical switch is improved. In one embodiment, the piezoelectric properties of these layers are selected such that their shape changes sufficiently in response to activation light, thereby creating a piezoelectric element that blocks the passage of signal light through the signal channel. Is done.

  FIG. 1A shows an optical switch 100 controlled by activation light, comprising a signal channel 102 and a piezoelectric element 104. The signal channel guides the transmission of light in a limited area along a defined path. The signal channel is formed by a light guiding structure or a combination of a plurality of light guiding structures capable of guiding light within a limited area along a defined path. Structures that can form signal channels include, for example, optical fibers, substrates such as lithium niobate, or other transparent piezoelectric materials with signal channels, optical waveguides, and chambers for holding compressible materials. Including. In the embodiment of FIG. 1A, the signal channel is formed by a monolithic light guiding element.

The piezoelectric element 104 is made of a piezoelectric material. Examples of piezoelectric materials that can be used to form piezoelectric elements include quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lead zirconate (PbZrO ₃ ), lead titanate (PbTiO ₃ ) and zircon. There are crystalline piezoelectric materials such as lead acid titanate. Examples of piezoelectric materials that can be oriented in a magnetic field are lead zirconate and lead titanate or lead zirconate titanate. Quartz and lithium niobate are examples of transparent piezoelectric materials.

  The piezoelectric element 104 has at least two layers 106 and 108 of piezoelectric material having different piezoelectric properties. Different piezoelectric properties of different layers can, for example, 1) different degrees of expansion and / or contraction in response to the same electric field, 2) different responses to the same electric field (eg one of the layers has a first orientation) Expands in response to an electric field and the other layers expand in response to an electric field having a second orientation perpendicular to the first orientation), 3) different polarities, 4) different strains, 5) different hysteresis 6) different capacitances, 7) different impedances, 8) different resistivity, 9) different thermal histories and 10) different electromagnetic histories.

  The piezoelectric characteristics of the piezoelectric material include, for example, 1) the type of the piezoelectric material, 2) the crystal orientation of the piezoelectric material, 3) the doping level in the piezoelectric material, 4) the density of the piezoelectric material, and 5) the void density of the piezoelectric material. 6) the chemical composition of the piezoelectric material, 7) the thermal history of the piezoelectric material, and 8) the electromagnetic history of the piezoelectric material. The desired piezoelectric properties of the individual layers of piezoelectric material can be achieved, for example, by manipulating one or more of the parameters listed above.

  In one embodiment, layers of piezoelectric material that have different degrees of expansion and / or contraction in response to the same electric field are integrated into the piezoelectric element to change or bend the shape of the piezoelectric element in response to activation light. Turn into. For example, when two adjacent layers of a piezoelectric element that are attached to each other to form a monolithic element expand by different amounts in response to the same activation light, the piezoelectric element bends. In one embodiment, the piezoelectric element comprises at least two layers of piezoelectric material having different piezoelectric properties formed as a monolithic element. For example, piezoelectric elements are formed by stacking layers of piezoelectric material together using semiconductor processing techniques such as crystal growth, vapor deposition, sputtering, ion implantation, and the like. In one embodiment, the layers of the piezoelectric element have different crystal orientations, so the two layers respond differently to the same electric field. For example, the two layers have a crystal orientation perpendicular to each other. In other embodiments, at least one of the plurality of layers of piezoelectric elements is made of an organic material.

  By using a piezoelectric element with layers of piezoelectric material having different piezoelectric properties, the response of the piezoelectric element can be selected to optimize on / off switching. For example, the piezoelectric properties of a layer 1) maximize the shape change of the piezoelectric element in response to the activation light, 2) minimize the hysteresis, 3) the amount of power required to change the shape of the piezoelectric element. And 4) can be selected to reduce the amount of heat generated by the switching technique.

  Next, the operation of the optical switch 100 shown in FIG. 1A will be described with reference to FIGS. 1A and 1B. FIG. 1A shows the piezoelectric element 104 in an inactive state. In the inactive state, the shape of the piezoelectric element does not change from its normal state. The normal state of the piezoelectric element is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 1A, the piezoelectric element is essentially flat in the inactive state. This flat shape of the piezoelectric element allows the signal light 110 to pass through the signal channel 104, as indicated by the signal light incident on and emitted from the signal channel.

  FIG. 1B shows an activated piezoelectric element 104 obtained by applying an activation light 112 to the piezoelectric element. In the embodiment of FIG. 1B, activation light is applied to the piezoelectric element by directing the activation light to the signal channel 102 in parallel with the signal light 110. This activation light provides an electric field that affects the piezoelectric material. In the active state, the shape of the piezoelectric element changes sufficiently to prevent the signal light from passing through the signal channel. The blocking of the signal light is indicated by the absence of signal light exiting from the signal channel. When the activation light is removed from the signal channel, the piezoelectric element returns to its normal shape and the signal light can again pass through the signal channel.

  As described above, activation of the piezoelectric element 104 in response to the activation light 112 changes the shape of the piezoelectric element, thereby changing at least one dimension of the signal channel 102. 2A is a cross-sectional view of the signal channel and piezoelectric element of FIG. 1A when the piezoelectric element is in an inactive state. 2B is a cross-sectional view of the signal channel and piezoelectric element of FIG. 1B when the piezoelectric element is in an active state. In the active state, the piezoelectric element enters the signal channel and reduces at least one dimension of the signal channel. As shown in FIGS. 2A and 2B, the cross-sectional area of the signal channel is smaller in the active state (FIG. 2B) than in the inactive state (FIG. 2A).

  As can be seen from the embodiment of FIGS. 1A-2B, there is still an opening in the signal channel 102 even if the piezoelectric element 104 is in an active state. Even though the piezoelectric element is in the active state, there is still an opening in the signal channel, but the opening in the signal channel is small enough so that the signal light 110 is prevented from passing through the signal channel. The ability of the signal light to pass through the signal channel is a function of the size of the signal channel and the wavelength of the signal light. In general, light having a short wavelength can pass through a signal channel having a shorter dimension than light having a long wavelength.

  FIG. 3 shows a graph of the relationship between optical signal attenuation and signal channel dimensions. As shown in FIG. 3, the attenuation of the optical signal changes abruptly when the dimensions of the signal channel reach a specific dimension, referred to herein as the cutoff dimension. For example, for dimensions shorter than the cutoff dimension (eg, about 5 angstroms), the attenuation increases rapidly, and for dimensions longer than the cutoff dimension, the attenuation decreases rapidly. As shown in FIG. 3, this steep response to changes in the signal channel dimensions in the vicinity of the cutoff dimension causes the signal channel dimensions to switch between a dimension longer than the cutoff dimension and a dimension shorter than the cutoff dimension. By switching the activation light, high-speed on / off switching is possible.

  As described above, the state of the optical switch 100 is activated by applying the activation light 112 to the piezoelectric element 104. The activation light can be applied to the piezoelectric element using various techniques. Several exemplary techniques for applying activation light to the piezoelectric element are described with reference to FIGS. 4A-5B.

  FIGS. 4A and 4B illustrate a technique for changing the state of the optical switch 100, including applying an activation light 112 having a wavelength shorter than that of the signal light 110. Referring to FIG. 4A, the optical switch 100 is in an ON state in which activation light is not applied to the piezoelectric element 104, and thus the signal light 110 passes through the signal channel 102. As shown in FIG. 4B, the activation light 112 is applied to the piezoelectric element 104, and the state of the optical switch 100 changes from on to off. In the OFF state, the shape of the piezoelectric element 104 is changed by the activation light 112 and the signal light 110 is prevented from passing through the signal channel 102. In this embodiment, the activation light 112 has a wavelength shorter than that of the signal light 110. Specifically, the wavelength of the activation light 112 is sufficiently short so that even when the optical switch 100 is in the off state, the activation light 112 can still pass through the signal channel. FIG. 4B shows a case where the activation light 112 having a wavelength shorter than that of the signal light 110 can pass through the signal channel 102 even when the optical switch 100 is in the OFF state.

  FIGS. 5A and 5B illustrate a technique for changing the state of the optical switch 100, where applying activation light provides the piezoelectric element 104 with two optical signals 112A and 112B that are out of phase with each other. Then, one of these optical signals, ie, the optical signal 112A in the illustrated embodiment, is removed, and the other optical signal, ie, the optical signal in the illustrated embodiment, is optical. Including leaving the signal 112B as the activation light. For this embodiment, these two signals 112A and 112B are out of phase (eg, 180 degrees out of phase) so that their electric fields effectively cancel each other. These two signals out of phase cancel each other while being simultaneously applied to the piezoelectric element 104, so that the piezoelectric element 104 is not activated. When one of these optical signals is removed, the electric field of the other optical signal is not canceled out, so that the piezoelectric element is activated by the optical signal. FIG. 5A shows the signal light 110 and the components of the optical signals 112A and 112B that pass through the signal channel 102 and are out of phase. As explained above, in this case, these two optical signals out of phase cancel each other, so that the piezoelectric element 104 is not activated. In FIG. 5B, one of these out-of-phase optical signals 112A is removed and the other optical signal 112B is left as activation light. This activation light activates the piezoelectric element 104 and prevents the signal light 110 (and the activation light in this case) from passing through the signal channel. In other embodiments, the optical output of one of these two optical signals can be greater than the optical output of the other optical signal, thereby overcoming the cancellation effect and providing activation light. it can.

  Another technique for optimizing the performance of a light activated optical switch is to increase the electric field applied to the piezoelectric element in response to the activated light. According to one embodiment of the present invention, at least one conductive layer is disposed adjacent to the piezoelectric element of the photoactive optical switch to enhance the electric field applied to the piezoelectric element in response to the activation light. Is done. This conductive layer has free electrons or holes that are attracted and collected to the surface adjacent to the piezoelectric element when activation light is applied to the piezoelectric element. By collecting free electrons in the vicinity of the piezoelectric element, the electric field applied to the piezoelectric element is strengthened in response to the activation light. By using an enhanced electric field, the performance of the piezoelectric element can be improved and the performance of the optical switch can be improved. For example, an electric field enhanced by the contribution of an adjacent conductive layer can activate a piezoelectric element with a smaller light output and / or piezoelectrically faster than if there is no conductive layer adjacent to the piezoelectric element. The element can be activated.

  Without the conductive layer, only the electric field of the activation light activates the piezoelectric element. If a conductive layer is used, this conductive layer provides a charge that is collected or dispersed by the electric field of the activation light. The electric field of the activation light is strengthened by the electric field of the collected charges. In this case, the electric field of the activation light and the electric field of the collected charges act on the piezoelectric element. In the case of a dispersed charge, since it consists of a positive charge and a negative charge, the other appears when one is dispersed. In this case, the electric field of the activation light is strengthened by the electric field of the generated charge, and the effect on the piezoelectric element is improved. Electrons move through metal conductors, but holes can move through semiconductors.

  FIG. 6A illustrates one embodiment of a light activated optical switch 120 that includes a signal channel 122, a piezoelectric element 124, and a conductive layer 126 adjacent to the piezoelectric element 124. The signal channel 122 and piezoelectric element 124 are similar to the signal channel and piezoelectric element described above, but the piezoelectric element 124 need not necessarily comprise different layers of piezoelectric material having different piezoelectric properties. Conductive layer 126 may be a highly conductive material such as lead, tungsten, other metals, boron doped silicon, arsenic doped silicon, doped gallium arsenide, and / or other semiconductor materials. It is. In one embodiment, the conductive layer 126 is attached to the surface of the piezoelectric element 124. For example, the conductive layer 126 is deposited on the major surface of the piezoelectric element 124 using a metal deposition technique. In an alternative embodiment, conductive layer 126 is formed of a semiconductor material that moves not only negative charges but also positive charges or negative charges.

  Next, the operation of the optical switch 120 shown in FIG. 6A will be described with reference to FIGS. 6A and 6B. FIG. 6A shows the piezoelectric element 124 in an inactive state. In the inactive state, the shape of the piezoelectric element 124 does not change from its normal state. The normal state of the piezoelectric element 124 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 6A, the piezoelectric element 124 is essentially flat in the inactive state. This flat shape of the piezoelectric element allows the signal light 128 to pass through the signal channel 122 as indicated by the signal light 128 entering and exiting the signal channel 122.

  FIG. 6B shows the activated piezoelectric element 124 obtained by applying the activation light 129 to the piezoelectric element 124. In the embodiment of FIG. 6B, the activation light 129 is drawn to the surface of the conductive layer 126 closest to the piezoelectric element 124 by directing the activation light 129 to the signal channel 122 in parallel with the signal light 128. In the active state, the shape of the piezoelectric element 124 changes sufficiently to prevent the signal light 128 from passing through the signal channel 122. The blockage of the signal light 128 is indicated by the absence of the signal light 128 exiting from the signal channel 122. The additional electrons in the vicinity of the piezoelectric material coupled to the conductive layer 126 enhances the electric field applied to the piezoelectric material of the piezoelectric element 124. To increase the electric field associated with the conductive layer 126, for example, to increase the magnitude of the change in the shape of the piezoelectric element 124, to increase the speed of change in the shape of the piezoelectric element 124, and to achieve a desired shape change Benefits are provided including a reduction in the amount of activation light required.

  FIG. 7 shows the effect of the electric field 130 of the activation light 129 on the electrons of the conductive layer 126 of FIGS. 6A and 6B. In FIG. 7, the surface 132 is the surface of the conductive layer 126 closest to the activation light 129, and the surface 134 is the surface of the conductive layer 126 farthest from the activation light 129. The comb structure in FIG. 7 represents an electric field under the influence of the conductive layer 126. The individual teeth 136 of the comb structure represent a portion of the electric field, some of which have wide extension portions 138 at their distal portions. These broad extensions 138 represent the strong electric field caused by the charge moving through the conductive layer 126 adjacent to the piezoelectric element 124. The dash line 140 represents the charge that moves in response to the electric field of the activation light 129. If the electric field is negative, the charge in the conductive layer 126 is driven away from near the surface 132 of the conductive layer, thus strengthening the negative electric field. If the electric field is positive, the charge in the conductive layer will move closer to the surface 132 of the conductive layer, thus strengthening the electric field. Since the piezoelectric material is not a conductor but a dielectric material, the charge does not move when the conductive layer 126 is not present. Referring to FIG. 7, if the conductive layer 126 is removed and only the piezoelectric element (not shown) is left, the comb tooth 136 does not have an extended portion 138 thereon.

  FIG. 8 shows an optical switch system 150 comprising the light activated optical switch 152 described above with reference to FIGS. 1A-7. The optical switch system 150 of FIG. 8 further includes an activation light system 154 including an activation light source 156 and an activation light controller 158. The optical switch system 150 is optically connected to the signal light source 160 so as to receive the signal light 161. In the embodiment of FIG. 8, the signal light 161 is provided to the optical switch 152 via the signal light path 162, and the activation light 163 is provided to the optical switch 152 via the activation light path 164 and the signal light path 162. Is done. The signal light 161 and the activation light 163 are combined by a coupler 166. The output of the optical switch 152 is emitted through the output path 168.

  The activation light system 154 controls application of the activation light 163 to the piezoelectric element (not shown) of the optical switch 152. In the embodiment of FIG. 8, the activation light source 156 generates activation light having the desired characteristics, eg, desired wavelength, intensity, phase and polarization of the activation light in relation to other light in the signal channel. , A light source such as a light emitting diode (LED) or laser, and an activation light controller 158 controls the transmission of activation light 163 from the activation light system. In one embodiment, in order to sufficiently change the shape of the piezoelectric element of the optical switch 152, the intensity of the activation light 163 must be sufficiently large, and in one embodiment, the activation light The intensity of 163 is greater than the intensity of the signal light 161. The wavelength of the activation light 163 may be shorter or longer than the wavelength of the signal light 161. As described above, when the wavelength of the activation light 163 is sufficiently short, the activation light 163 can pass through the signal channel even if the piezoelectric element is activated, and the signal light 163 is blocked.

  The activation light system 154 can be configured to provide activation light 163 to the optical switch 152 in many different ways. For example, in one embodiment, activation light 163 is switched on and off by a second photoactive optical switch, and in another embodiment, activation light 163 is provided by changing the angle of the mirror. In other embodiments, the LED or laser is turned on / off, and in other embodiments, other switches can be used to control the activation light 163. The signal light source 160 generates the signal light 161 that is switched on and off by the optical switch 152 (that is, the optical switch 152 is allowed to pass and the optical switch 152 is blocked). In one embodiment, the signal light source 160 is an optical transmitter that transmits digital data by modulating the optical signal (eg, by frequency modulation or amplitude modulation). In one embodiment, the signal light 161 output by the signal light source 160 is an optical signal that communicates digital data in several ways (eg, amplitude or frequency modulation, logic, etc.), while an activated light source. The activation light 163 output by 156 does not communicate digital data. For example, the signal light 161 carries digital data in a modulated light format, and the activation light 163 is modulated and does not carry digital data.

  In operation, signal light 161 is provided to optical switch 152 via signal light source 160 and activation light system 154 controls application of activation light 163 to the piezoelectric elements of optical switch 152. In one embodiment, if the activation light system 154 does not provide activation light 163 to the optical switch 152, the signal light 161 passes through the optical switch 152 and the activation light system 154 activates the optical switch 152. When the light 163 is provided, the passage of the optical switch 152 is blocked.

  In the case of the optical switch described with reference to FIGS. 1A to 6B, the signal light and the activation light are transmitted through the same signal channel. Various techniques can be used to combine the signal light and the activation light into the same signal channel. FIG. 9 shows one embodiment of an optical switch 152 and an optical coupler 166 that is used to couple the signal light 161 and the activation light 163 into the same signal channel 122. In the embodiment of FIG. 9, signal light 161 travels in a signal light path 162, such as a signal fiber, and activation light 163 travels in an activation light path 164, such as an activation fiber. The signal light 161 and the activation light 163 are coupled to the signal channel 122 by the optical coupler 166. For the embodiment shown in FIG. 9, an optical coupler is shown, but other suitable techniques for coupling the signal light 161 and the activation light 163 to the same signal channel 122 may be used. It will be understood.

  10A-10E illustrate different embodiments of the light activated optical switch described above with reference to FIGS. 1A-9. FIG. 10A shows one embodiment of a light activated optical switch 170, where the piezoelectric element 172 has three or more layers 174 of piezoelectric material with different piezoelectric properties. In the embodiment shown in FIG. 10, the piezoelectric element 172 has four layers 174 of piezoelectric material. In one embodiment, the different layers 174 of piezoelectric material have different piezoelectric properties, and in other embodiments, the different layers of piezoelectric material have alternating piezoelectric properties. It should be understood that the number and arrangement of piezoelectric layers 174 can include many different variations.

  FIG. 10B shows one embodiment of a light activated optical switch 176 with a conductive layer 178 sandwiched between two layers 180 of the piezoelectric element 182. This embodiment allows the piezoelectric element 182 to be oriented by placing a charge on the conductive layer 178, and the shape of the individual layers 180 of the piezoelectric element 182 because the piezoelectric layer 180 is proximate to the conductive layer 178. Make a change.

  FIG. 10C illustrates one embodiment of a light activated optical switch 184 in which a plurality of conductive layers 185 are sandwiched between a plurality of different layers 186 of the piezoelectric element 187. In this embodiment, conductive layers 185 are alternately deposited between different layers 186 of piezoelectric elements 187. The plurality of layers 185 of conductive material between the piezoelectric layers 186 can individually polarize the individual layers 186 of piezoelectric material to different orientations by applying a charge to the conductive layer 185. Thus, the action of the piezoelectric layers 186 that interact with each other can further increase the change in the shape of the piezoelectric element 187.

  In general, these multiple conductive layers allow management of the hysteresis of the piezoelectric element. These multiple conductive layers can lower the temperature that should be raised in the piezoelectric element in order to change the orientation of the piezoelectric material. The plurality of conductive layers can increase the change in the shape of the piezoelectric element. These multiple conductive layers provide many mechanical, electrical, thermal and other physical properties of the optical switch that are managed so that the optical switch can be more easily configured, maintained, and used. Allows management of In one embodiment, the different layers of piezoelectric material and the conductive layer are formed in a monolithic stack structure. The monolithic stack structure can be formed, for example, using known semiconductor processing techniques, such as crystal growth, metal deposition, sputtering, ion implantation, and the like.

  In some cases, the hysteresis of the piezoelectric element can limit the rate at which the state of a photoactive optical switch constructed using the piezoelectric element can be changed from one state to another. In one embodiment, a 3000 Å thick layer of lead zirconate titanate (PZT) is deposited on the substrate. The layer of PZT has a given proportion of lead and a given proportion of zirconium and titanium. A 3000 Å layer of PZT is then deposited over the first layer. This layer has more lead and zirconium, but the proportion of titanium at the top of this layer is reduced. By using these layers, the hysteresis exhibited by the resulting piezoelectric element is reduced when compared to piezoelectric elements that do not have similar layers. A piezoelectric element having a quick response can be manufactured by depositing more alternating layers to form the piezoelectric element. If all these layers are deposited on the conductive layer, the electric field of the activation light is strengthened, and a photoactive optical switch having a quick response is formed.

  FIG. 10D shows one embodiment of a light activated optical switch 188 with a multilayer piezoelectric element 189 on one side of the signal channel 190 and a conductive layer 191 on both sides of the signal channel 190. Multiple conductive layers 191 improve the response of the switch.

  FIG. 10E shows one embodiment of a light activated optical switch 192 with multilayer piezoelectric elements 194 and conductive layers 196 on both sides of the signal channel 198. In one embodiment, FIG. 10E shows a cross-sectional view of an optical fiber, in which a piezoelectric element and a conductive layer are formed in a strip shape around the optical fiber. In this embodiment, the fiber is a compressible material.

  FIG. 11A shows one embodiment of a light activated optical switch 200 comprising a signal channel 202, a piezoelectric element 204 and a conductive layer 206, a portion of the signal channel being a chamber 208 filled with a compressible material. It has. The compressible material may be, for example, a gas such as argon or nitrogen, or a material such as petroleum distillate or silicon rubber. Chamber 208 filled with a compressible material is adjacent to piezoelectric element 204 so that piezoelectric element 204 can expand into chamber 208 when activated by activation light. In one embodiment, the piezoelectric element 204 forms part of the chamber 208. In one embodiment, at least a portion of the chamber 204 is formed of a transparent material.

  Next, the operation of the optical switch 200 shown in FIG. 11A will be described with reference to FIGS. 11A and 11B. FIG. 11A shows the piezoelectric element 204 in an inactive state. In the inactive state, the shape of the piezoelectric element 204 does not change from its normal state. The normal state of the piezoelectric element 204 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 11A, the piezoelectric element 204 is essentially flat in the inactive state and does not protrude into the chamber 208. This flat shape of the piezoelectric element 204 allows the signal light 210 to pass through the signal channel 202 (including the chamber 208) as indicated by the signal light 210 incident on and exiting the signal channel 202.

  FIG. 11B shows the activated piezoelectric element 204 obtained by applying the activation light 212 to the piezoelectric element 204. In the embodiment of FIG. 11B, the activation light 212 is applied to the piezoelectric element 204 by directing the activation light 212 to the signal channel 202 in parallel with the signal light 210. When the activation light 212 is applied to the piezoelectric element 204, the piezoelectric element 204 protrudes into the chamber 208, thereby compressing the compressible material in the chamber. In the active state, the shape of the piezoelectric element 204 changes sufficiently to prevent the signal light 210 from passing through the signal channel 202. The interruption of the signal light 210 is indicated by the absence of the signal light 210 exiting from the signal channel 202. When the activation light 212 is removed from the signal channel 202, the piezoelectric element 204 returns to its normal shape, allowing the signal light 210 to pass. In the absence of the activation light 212, the pressure of the compressed material in the chamber 208 facilitates the return of the piezoelectric element 204 to its normal state.

  FIG. 12A shows one embodiment of a light activated optical switch 220 comprising a signal channel 222, a piezoelectric element 224, and a conductive layer 226 adjacent to the piezoelectric element, where the signal channel 222 is an optical fiber, The element 224 and the conductive layer 226 are formed in a belt shape around the circumference of the optical fiber. FIG. 12A shows the piezoelectric element 224 in an inactive state. In the inactive state, the shape of the piezoelectric element 224 has not changed from its normal state. The normal state of the piezoelectric element 224 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 12A, the piezoelectric element 224 is essentially flat in the inactive state. This flat shape of the piezoelectric element 224 allows the signal light 230 to pass through the signal channel 222 as indicated by the signal light 230 entering and exiting the signal channel 222. FIG. 12B shows an activated piezoelectric element 224 obtained by applying activation light 232 to the piezoelectric element 224. In the embodiment of FIG. 12B, the activation light 232 is applied to the piezoelectric element 224 by directing the activation light 232 to the signal channel 222 in parallel with the signal light 230. In the active state, the shape of the piezoelectric element 224 is sufficiently changed to prevent the signal light 230 from passing through the signal channel 222. For example, the change in the shape of the piezoelectric element 224 has an effect of blocking the signal light 230 by narrowing the optical fiber like a belt. The interruption of the signal light 230 is indicated by the absence of the signal light 230 exiting from the signal channel 222. When the activation light 232 is removed from the signal channel 222, the piezoelectric element 224 returns to its normal shape and the signal light 230 can again pass through the signal channel 222.

  FIG. 13A illustrates one embodiment of a photoactive optical switch 240 that includes a signal channel 242, a piezoelectric element 244, and a conductive layer 246 adjacent to the piezoelectric element 244, the piezoelectric element 244 being made of a transparent material. Forming at least part of the signal channel 242. FIG. 13A shows the piezoelectric element 244 in an inactive state. In the inactive state, the shape of the piezoelectric element 244 has not changed from its normal state. The normal state of the piezoelectric element 244 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 13A, the piezoelectric element 244 is essentially flat in the inactive state. This flat shape of the piezoelectric element 244 allows the signal light 250 to pass through the signal channel 242 as indicated by the signal light 250 entering and exiting the signal channel 242. FIG. 13B shows an activated piezoelectric element 244 obtained by applying activation light 252 to the piezoelectric element. In the embodiment of FIG. 13B, the activation light 252 is applied to the piezoelectric element 244 by directing the activation light 252 to the signal channel 242 in parallel with the signal light 250. In the active state, the shape of the piezoelectric element 244 changes sufficiently to prevent the signal light 250 from passing through the signal channel 242. For example, the change in the shape of the piezoelectric element 244 has an effect of blocking the signal light 250 by narrowing the signal channel 242 like a belt. The blockage of the signal light 250 is indicated by the absence of the signal light 250 exiting from the signal channel 242. When the activation light 252 is removed from the signal channel 242, the piezoelectric element 244 returns to its normal shape and the signal light 250 can again pass through the signal channel 242.

  In one embodiment, the piezoelectric element and the signal channel are not changed from turning on (light passes through the signal channel) to off (blocking light) by applying activation light. , Configured relative to each other to change from off to on.

  Some piezoelectric materials have a crystalline orientation that must be aligned with the electric field that causes the shape change. Other piezoelectric materials can be heated and oriented in a magnetic field to respond in a desired direction to an applied electric field. When constructing an optically active optical switch, the crystal orientation or the magnetic orientation of the piezoelectric material must be oriented so that it has a maximum shape change in the direction of 90 degrees (ie perpendicular) to the direction of the signal light in the signal channel. I must. In one embodiment, the electric field that triggers switching is 90 degrees (ie, perpendicular) to the path of light in the optical channel.

Hereinafter, a desired interaction will be described. Using the power of the light in the channel (in watts), the electric field (in volts) required to activate the photoactive optical switch is calculated. This calculation is performed using a pointing vector equation represented by E = (2 μ ₀ cP) ^1/2 . μ ₀ is 4π × 10E-7 Weber / ampere-meter, c is 3 × 10E + 8 meters / second, E is the electric field in volts, and P is the output in watts. Using this relationship, it can be seen that the voltage developed by the 150 milliwatt signal into the 1/4 micron channel is 10 volts. In one embodiment, this voltage is used to activate the optical trigger optical switch, thereby turning the switch on or off (eg, allowing signal light to pass through the signal channel or Passage is blocked). An example of the size change that this 10 volt can bring is as follows. For a channel with a height of 2065 angstroms, 10 volt changes its size by 40 angstroms when lead zirconate titanate is used. Lead zirconate titanate has a piezoelectric strain coefficient of 3.90 times 10E-10 meters / volt. 818 nm (8180 angstroms) of light, which is widely used for optical fibers, can travel a channel that is only slightly longer than 2045 angstroms, and cannot travel a shorter channel. When the 2065 Angstrom channel changes to 2014 Angstrom, the signal light is blocked. Light with a wavelength below 8056 angstroms can still pass through the signal channel. The photoactive optical switch can be turned on or off at a speed of 10E-11 seconds or less. For this, the effect that the electric field and magnetic field of light have on the medium through which the light moves is used. For the attenuation (A) of the signal in the waveguide, the equation giving the attenuation in decibels per signal travel of 1,609.3 m (1 mile) is

It is.
K is a constant for the material making up the walls of the channel and the value of K is 821.3 for lead. In one embodiment, the optical switch cannot exactly follow the graph of FIG. 3 because only one wall of the optical switch is made of lead, but this graph is shown for illustrative purposes only. Absent. If it is smaller, “a” in the equation is the length of the side of the waveguide. The frequency (f) of the signal under consideration is expressed as a ratio to the cutoff frequency (f ₀ ) in the channel. This equation is for TE ₀ , ₁ mode wave propagation. In one embodiment, the waveguide size is selected such that this TE _{0, 1} mode is the only possible mode. Since this relationship has been studied to shrink the waveguide dimensions for a given signal, the attenuation increases as the size of the signal channel shrinks and proceeds toward infinity as the cutoff frequency is approached. This equation is described on page 263 of "Radio Technician Handbook" by Frederic Terman, published in 1943 by McGraw-Hill Book Company.

  Referring now to FIG. 14A, an optical switch 300 with a signal channel 302 and a plurality of piezoelectric elements is shown. The plurality of piezoelectric elements are preferably spaced non-uniformly along the length of the signal channel 302. In the illustrated embodiment, three generally rectangular piezoelectric elements 304, 305, 306 are distributed at non-uniform intervals along the length of the signal channel 302. The shapes of the piezoelectric elements 304, 305, and 306 are controlled by the activation light. The signal channel 302 guides the transmission of light in a limited area along a defined path. The signal channel 302 is formed by a light guiding structure or a combination of structures that can guide light within a limited area along a defined path. Structures that can form signal channels include, for example, substrates such as optical fibers, lithium niobate, or other transparent channels with signal channels, optical waveguides, and chambers for holding compressible materials. There is a piezoelectric material. In the embodiment of FIG. 14A, the signal channel 302 is preferably formed by a monolithic light guiding element.

The piezoelectric elements 304, 305, and 306 are preferably formed of a piezoelectric material. Examples of piezoelectric materials that can be used to form piezoelectric elements include quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lead zirconate (PbZrO ₃ ), lead titanate (PbTiO ₃ ) and zircon. There are crystalline piezoelectric materials such as lead acid titanate. Examples of piezoelectric materials that can be oriented in a magnetic field are lead zirconate and lead titanate or lead zirconate titanate. Quartz and lithium niobate are examples of transparent piezoelectric materials.

  Each of the piezoelectric elements 304, 305, 306 preferably comprises at least two layers 307, 308 of piezoelectric material having different piezoelectric properties. Different piezoelectric properties of different layers 307, 308 include, for example, 1) different degrees of expansion and / or contraction in response to the same electric field, and 2) different responses to the same electric field (eg, one of the plurality of layers is first The other layers expand in response to an electric field having a second orientation perpendicular to the first orientation), 3) different polarities, 4) different strains, 5) different hysteresis, 6) different capacitance, 7) different impedance, 8) different resistivity, 9) different thermal history, and 10) different electromagnetic history.

  Next, the operation of the optical switch 300 shown in FIG. 14A will be further described with reference to FIG. 14B. FIG. 14A shows the piezoelectric elements 304, 305, and 306 in an inactive state. In the inactive state, the shape of the piezoelectric elements 304, 305, 306 has not changed from its normal state. The normal state of the piezoelectric elements 304, 305, and 306 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 14A, the piezoelectric elements 304, 305, 306 are essentially flat in the inactive state. This flat shape of the piezoelectric elements 304, 305, 306 allows the signal light 310 to pass through the signal channel 302, as indicated by the signal light 310 incident on the signal channel 302 and the signal light 310 emitted from the signal channel 302. .

  FIG. 14B shows active piezoelectric elements 304, 305, 306 obtained by applying activation light 312 to the piezoelectric elements 304, 305, 306. In the embodiment of FIG. 14B, the activation light 312 is applied to the piezoelectric elements 304, 305, 306 by directing the activation light 312 to the signal channel 302 in parallel with the signal light 310. The activation light 312 supplies an electric field that affects the piezoelectric material. In the active state, the shapes of the piezoelectric elements 304, 305, and 306 are sufficiently changed, and the signal light 310 is prevented from passing through the signal channel 302. The interruption of the signal light 310 is indicated by the absence of the signal light 310 exiting from the signal channel 302. When the activation light 312 is removed from the signal channel 302, the piezoelectric elements 304, 305, 306 return to their normal shape and the signal light 310 can pass through the signal channel 302 again.

  As described above, activation of the piezoelectric elements 304, 305, 306 in response to the activation light 312 changes the shape of the piezoelectric elements 304, 305, 306, thereby at least one of the signal channels 302. One dimension changes. 15A is a cross-sectional view of the signal channel 302 and the piezoelectric element 305 of FIG. 14A when the piezoelectric element 305 is in an inactive state. FIG. 15B is a cross-sectional view of the signal channel 302 and the piezoelectric element 305 of FIG. 14B when the piezoelectric element 305 is in an active state. In the active state, the piezoelectric element 305 extends into the signal channel 302 and at least one dimension of the signal channel 302 is shortened. As shown in FIGS. 15A and 15B, the cross-sectional area of the signal channel 302 is smaller in the active state (FIG. 15B) than in the inactive state (FIG. 15A).

  As can be seen from the embodiment of FIGS. 14A-15B, there is still an opening in the signal channel 302 even when the piezoelectric elements 304, 305, 306 are in the active state. Even if the piezoelectric elements 304, 305, 306 are in the active state, the signal channel 302 still has an opening, but the opening in the signal channel 302 is sufficiently small so that the signal light 310 can pass through the signal channel 302. Be blocked. The ability of signal light 310 to pass through signal channel 302 is a function of the size of signal channel 302 and the wavelength of signal light 310. In general, light having a shorter wavelength can pass through the signal channel 302 having a shorter dimension than light having a longer wavelength.

  Referring now to FIG. 16A, an optical switch 400 with a signal channel 402 and a plurality of piezoelectric elements is shown. The plurality of piezoelectric elements are preferably spaced non-uniformly along the length of the signal channel 402. In the illustrated embodiment, four generally cylindrical piezoelectric elements 404, 405, 406, 407 are distributed at non-uniform intervals along the length of the signal channel 402. The shapes of the piezoelectric elements 404, 405, 406, and 407 are controlled by the activation light. The signal channel 402 guides the transmission of light in a limited area along a defined path. The signal channel is formed by a light guiding structure or by a combination of structures that can guide light within a limited area along a defined path. Structures that can form signal channels include, for example, substrates such as optical fibers, lithium niobate, or other transparent channels with signal channels, optical waveguides, and chambers for holding compressible materials. There is a piezoelectric material. In the embodiment of FIG. 16A, the signal channel 402 is preferably formed by a monolithic light guiding element.

The piezoelectric elements 404, 405, 406, and 407 are preferably formed of a piezoelectric material. Examples of piezoelectric materials that can be used to form piezoelectric elements include quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lead zirconate (PbZrO ₃ ), lead titanate (PbTiO ₃ ) and zircon. There are crystalline piezoelectric materials such as lead acid titanate. Examples of piezoelectric materials that can be oriented in a magnetic field are lead zirconate and lead titanate or lead zirconate titanate. Quartz and lithium niobate are examples of transparent piezoelectric materials.

  Each of the piezoelectric elements 404, 405, 406, 407 preferably comprises at least two layers 408, 409 of piezoelectric material having different piezoelectric properties. Different piezoelectric properties of different layers include, for example, 1) different degrees of expansion and / or contraction in response to the same electric field, and 2) different responses to the same electric field (eg, one of the layers has a first orientation). Expands in response to an electric field having and other layers expand in response to an electric field having a second orientation perpendicular to the first orientation)), 3) different polarities, 4) different strains, 5) different It can include hysteresis, 6) different capacitance, 7) different impedance, 8) different resistivity, 9) different thermal history and 10) different electromagnetic history.

  Next, the operation of the optical switch 400 shown in FIG. 16A will be further described with reference to FIG. 16B. FIG. 16A shows the piezoelectric elements 404, 405, 406, and 407 in an inactive state. In the inactive state, the shape of the piezoelectric elements 404, 405, 406, 407 has not changed from its normal state. The normal state of the piezoelectric elements 404, 405, 406, and 407 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 16A, the piezoelectric elements 404, 405, 406, 407 are essentially flat in the inactive state. This flat shape of the piezoelectric elements 404, 405, 406, 407 allows the signal light 410 to pass through the signal channel 402 as indicated by the signal light 410 incident on the signal channel 402 and the signal light 410 emitted from the signal channel 402. Allow.

  FIG. 16B shows the piezoelectric elements 404, 405, 406, and 407 in the active state obtained by applying the activation light 412 to the piezoelectric elements 404, 405, 406, and 407. In the embodiment of FIG. 16B, the activation light 412 is applied to the piezoelectric elements 404, 405, 406, 407 by directing the activation light 412 to the signal channel 402 in parallel with the signal light 410. The activation light 412 provides an electric field that affects the piezoelectric material. In the active state, the shapes of the piezoelectric elements 404, 405, 406, and 407 are sufficiently changed to prevent the signal light 410 from passing through the signal channel 402. The interruption of the signal light 410 is indicated by the absence of the signal light 410 exiting from the signal channel 402. When the activation light 412 is removed from the signal channel 402, the piezoelectric elements 404, 405, 406, 407 return to their normal shape and the signal light 410 can again pass through the signal channel 402.

  As explained above, activation of the piezoelectric elements 404, 405, 406, 407 in response to the activation light 412 changes the shape of the piezoelectric elements 404, 405, 406, 407, thereby changing the signal channel 402. At least one of the dimensions changes. 17A is a cross-sectional view of the signal channel 402 and piezoelectric element 406 of FIG. 16A when the piezoelectric element 406 is in an inactive state. FIG. 17B is a cross-sectional view of the signal channel 402 and the piezoelectric element 406 of FIG. 16B when the piezoelectric element 406 is in an active state. In the active state, the piezoelectric element 406 extends into the signal channel 402 and at least one dimension of the signal channel 402 is shortened. As shown in FIGS. 17A and 17B, the cross-sectional area of the signal channel 402 is smaller in the active state (FIG. 17B) than in the inactive state (FIG. 17A).

  As can be seen from the embodiments of FIGS. 16A-17B, there is still an opening in the signal channel 402 even when the piezoelectric elements 404, 405, 406, 407 are in the active state. Even if the piezoelectric elements 404, 405, 406, and 407 are in an active state, the signal channel 402 still has an opening, but the gap in the signal channel 402 is sufficiently small, so that the signal light 410 is transmitted through the signal channel 402. Passage is blocked. The ability of signal light 410 to pass through signal channel 402 is a function of the size of signal channel 402 and the wavelength of signal light 410. In general, light having a shorter wavelength can pass through a signal channel having a shorter dimension than light having a longer wavelength.

  Referring now to FIG. 18A, an optical switch 500 with a signal channel 502 and a plurality of piezoelectric elements is shown. The plurality of piezoelectric elements are preferably spaced non-uniformly along the length of the signal channel 502. In the illustrated embodiment, three generally elliptical columnar piezoelectric elements 504, 505, 506 are distributed at non-uniform intervals along the length of the signal channel 502. The shapes of the piezoelectric elements 504, 505, and 506 are controlled by the activation light. Signal channel 502 guides the transmission of light in a confined area along a defined path. The signal channel 502 is formed by a light guiding structure or a combination of structures that can guide light within a limited area along a defined path. Structures that can form signal channels include, for example, substrates such as optical fibers, lithium niobate, or other transparent channels with signal channels, optical waveguides, and chambers for holding compressible materials. There is a piezoelectric material. In the embodiment of FIG. 18A, the signal channel 502 is preferably formed by a monolithic light guiding element.

The piezoelectric elements 504, 505, and 506 are preferably formed of a piezoelectric material. Examples of piezoelectric materials that can be used to form piezoelectric elements include quartz (SiO ₂ ), lithium niobate (LiNbO ₃ ), lead zirconate (PbZrO ₃ ), lead titanate (PbTiO ₃ ) and zircon. There are crystalline piezoelectric materials such as lead acid titanate. Examples of piezoelectric materials that can be oriented in a magnetic field are lead zirconate and lead titanate or lead zirconate titanate. Quartz and lithium niobate are examples of transparent piezoelectric materials.

  Each of the piezoelectric elements 504, 505, 506 preferably comprises at least two layers 507, 508 of piezoelectric material having different piezoelectric properties. Different piezoelectric properties of the different layers 507, 508 include, for example, 1) different degrees of expansion and / or contraction in response to the same electric field, 2) different responses to the same electric field (eg, one of the layers is first The other layers expand in response to an electric field having a second orientation perpendicular to the first orientation), 3) different polarities, 4) different strains, 5) different hysteresis, 6) different capacitance, 7) different impedance, 8) different resistivity, 9) different thermal history and 10) different electromagnetic history.

  The piezoelectric properties of the piezoelectric material are, for example, 1) type of piezoelectric material, 2) crystal orientation of the piezoelectric material, 3) doping level in the piezoelectric material, 4) density of the piezoelectric material, 5) void density of the piezoelectric material, 6) It is a function of the chemical composition of the piezoelectric material, 7) the thermal history of the piezoelectric material, and 8) the electromagnetic history of the piezoelectric material. The desired piezoelectric properties of the individual layers of piezoelectric material can be achieved, for example, by manipulating one or more of the parameters listed above.

  Preferably, layers of piezoelectric material that differ in the degree of expansion and / or contraction in response to the same electric field are integrated into the piezoelectric element, thereby changing or bending the shape of the piezoelectric element in response to activation light. For example, if two adjacent layers of a piezoelectric element that are attached to each other to form a monolithic element expand by a different amount in response to the same activation light, the piezoelectric element will bend. In one embodiment, the piezoelectric element comprises at least two layers of piezoelectric material having different piezoelectric properties formed as a monolithic element. For example, piezoelectric elements are formed by stacking layers of piezoelectric material together using semiconductor processing techniques such as crystal growth, vapor deposition, sputtering, ion implantation, and the like. In one embodiment, the layers of the piezoelectric element have different crystal orientations, so the two layers respond differently to the same electric field. For example, the two layers have a crystal orientation perpendicular to each other. In other embodiments, at least one of the plurality of layers of piezoelectric elements is made of an organic material.

  By using a piezoelectric element with layers of piezoelectric material having different piezoelectric properties, the response of the piezoelectric element can be selected to optimize on / off switching. For example, the piezoelectric properties of the layers are: 1) to change the shape of the piezoelectric element in response to activation light, 2) to minimize the hysteresis, and 3) to change the shape of the piezoelectric element. 4) can be selected such that the amount of power required for the is reduced, and 4) the amount of heat generated by the switching technique is reduced.

  Next, the operation of the optical switch 500 shown in FIG. 18A will be further described with reference to FIG. 18B. FIG. 18A shows inactive piezoelectric elements 504, 505, and 506. In the inactive state, the shape of the piezoelectric elements 504, 505, 506 has not changed from its normal state. The normal state of the piezoelectric elements 504, 505 and 506 is the state of the piezoelectric element when no activation light is present. In the embodiment of FIG. 18A, the piezoelectric elements 504, 505, 506 are essentially flat in the inactive state. This flat shape of the piezoelectric elements 504, 505, 506 allows the signal light 510 to pass through the signal channel 502, as indicated by the signal light 510 incident on the signal channel 502 and the signal light 510 emitted from the signal channel 502. .

  18B shows active piezoelectric elements 504, 505, and 506 obtained by applying activation light 512 to the piezoelectric elements 504, 505, and 506. FIG. In the embodiment of FIG. 18B, activation light 512 is applied to piezoelectric elements 504, 505, 506 by directing activation light 512 to signal channel 502 in parallel with signal light 510. This activation light 512 provides an electric field that affects the piezoelectric material. In the active state, the shapes of the piezoelectric elements 504, 505, and 506 are sufficiently changed, and the signal light 510 is prevented from passing through the signal channel 502. The blockage of the signal light 510 is indicated by the lack of the signal light 510 exiting from the signal channel 502. When the activation light 512 is removed from the signal channel 502, the piezoelectric elements 504, 505, 506 return to their normal shape and the signal light 510 can again pass through the signal channel 502.

  As described above, activation of the piezoelectric elements 504, 505, 506 in response to the activation light 512 changes the shape of the piezoelectric elements 504, 505, 506, thereby at least one of the signal channels 502. One dimension changes. 19A is a cross-sectional view of the signal channel 502 and the piezoelectric element 505 of FIG. 18A when the piezoelectric element 505 is in an inactive state. FIG. 19B is a cross-sectional view of the signal channel 502 and the piezoelectric element 505 of FIG. 18B when the piezoelectric element 505 is in an active state. In the active state, the piezoelectric element 505 extends into the signal channel 502 and at least one dimension of the signal channel 502 is shortened. As shown in FIGS. 19A and 19B, the cross-sectional area of the signal channel 502 is smaller in the active state (FIG. 19B) than in the inactive state (FIG. 19A).

  As can be seen from the embodiment of FIGS. 18A-19B, there is still an opening in the signal channel 502 even when the piezoelectric elements 504, 505, 506 are in the active state. Even if the piezoelectric elements 504, 505, and 506 are in the active state, the signal channel 502 still has an opening, but the opening in the signal channel 502 is sufficiently small so that the signal light 510 is prevented from passing through the signal channel 502. The The ability of signal light 510 to pass through signal channel 502 is a function of the size of signal channel 502 and the wavelength of signal light 510. In general, light having a shorter wavelength can pass through a signal channel having a shorter dimension than light having a longer wavelength.

  As will be appreciated, all logic logic can be implemented using three logic gates. These logic gates are AND logic gates, OR logic gates, and NOR logic gates. These logic gates process the digital signal in a specific manner described using truth tables. The truth table gives a signal output from the gate when a specific signal is input to the gate.

  Table 1 is a truth table for the logical AND gate. 1 in the A input string and B input string indicates that a digital signal pulse is input to the gate. These inputs can be input to the A input or the B input. Only when an input signal appears at both the A input and the B input, a pulse is output as a result of the AND gate.

  Table 2 is a truth table for the logical OR gate. When an input signal appears at one or both of the A input and B input, a pulse is output as a result of the OR gate.

  Table 3 is a truth table for the logical NOR gate. A pulse is output as a result of the NOR gate only when an input signal does not appear at either the A input or the B input. The NOR gate is often described as an OR gate having a knot gate at its output. The logic knot gate receives the signal and converts the received signal into an inverted signal. When an input signal exists, no signal is output, and when no input signal exists, a signal is output.

  In current computer circuits, three transistors can be used to construct a logical AND gate or a logical OR gate for electrical digital signals. In addition, in a current computer circuit, a logic NOR gate can be constructed using four transistors. The transistor switches in 10E-9 seconds. This determines the speed at which the computer can function. Current computers function on electronic digital signal flow, not optical signal flow. The optical signal is also called an optical signal or a photonic signal.

  The present invention comprises an AND logic gate, an OR logic gate, and a NOR logic gate based on fiber optic switches that are driven by light rather than driven by electrical signals or transistor circuits. These gates do not require a battery, and by selecting appropriate switches, the gate size can be made small enough to meet semiconductor size constraints. An example of a light activated optical switch is disclosed in US Pat. No. 7,072,536, which is incorporated herein by reference. Although an example of a light activated optical switch is given, the logic gate can be formed using other types of light driven optical switches.

  In one embodiment of the invention, the light carrying the digital information for logic is a 1500 nm wavelength signal that is widely used in current fiber optic channels. This signal can be converted to a 750 nm signal using a periodically poled lithium niobate (PPLN) crystal that can double the frequency of the input signal. By doubling the frequency, the signal wavelength becomes half of the original wavelength. The change to half the wavelength as in this PPLN is only an example. Other wavelengths and means can also be used.

  It is also possible to generate 1500 nm wavelength light from 750 nm light using differently configured PPLN crystals. Usually, a PPLN element functions only for a specific wavelength and does not function simultaneously with other frequencies. Although the optical output is lost during these conversions, an optical amplifier can be used to boost the signal back to the required level. For the present disclosure, the required light output boost is included in the frequency doubling function.

  The light can be present in the fiber optic channel with light that is 180 degrees out of phase, so no light electric field appears. Light that is 180 degrees out of phase with the light cancels the light output of that light.

  Reference is now made to FIG. 20, which is a schematic diagram of a logic knot gate 600 for an optical fiber system. In FIG. 20, an optical channel 601 such as an optical fiber provides the 1500 nm signal required for the logic gate 600. An optical channel 603, such as an optical fiber, provides a 1500 nm signal that can be varied by a logic knot gate 600. The wavelength reducer 605 can double the frequency of the incoming signal and thus convert the incoming signal to a 750 nm signal. The wavelength reducer 605 incorporates all the optical amplification functions necessary to make the signal useful after frequency conversion is achieved. The optical channel 601 is coupled to the output of the wavelength reducer 605 and enters the optical switch 607. The optical switch 607 is the photoactive optical switch described above. The optical switch 607 can output a 1500 nm signal until a 750 nm signal is output from the wavelength reducer 605. When a 750 nm signal is output from the wavelength reducer 605, no signal is output from the optical switch 607. Optical channel 609 provides the output signal from logic knot gate 600. An output signal is provided only when no signal is input on the optical channel 603, and thus a logic not gate is provided.

  Reference is now made to FIG. 21, which is a schematic diagram of the logical AND gate 610. An optical channel 611 such as an optical fiber supplies a wavelength signal having a high frequency to the optical switch 612 in order to drive the switch 612. The optical channel 611 is coupled to another optical fiber channel, and the phase of the light in the optical channel 611 is incident on the first logic input provided by the phase matcher 616 along the optical channel 614 to the logical AND gate 610. After being matched with the light to be incident, it enters the optical switch 612. The optical channel 614 is split and half of the light is incident on the wavelength reducer 618 to provide input to the optical switch 612 and then incident on the phase matcher 616 before being coupled to the other optical channel. The other half of the light in the optical channel 614 is input directly to the optical switch 612.

  A second logic input is provided to logic AND gate 610 along optical channel 620. The optical channel 620 is split and half of the light is incident on the wavelength reducer 622 to provide input to the optical switch 612 and then incident on the phase matcher 624 before being coupled to the other optical channel. The other half of the light in the optical channel 614 is input directly to the optical switch 612.

  The optical channel 626 is coupled to another fiber optic channel and the phase of the light in the optical channel 626 is matched to the second logic input light on the optical channel 620 by the phase matcher 624 and then input to the optical switch 612. I will provide a. The output of logic AND gate 610 is provided along optical channel 628 and provides the AND functions shown in Table 1.

  An optical phase shifter 629 is provided so that the inputs from the optical channels 614, 620 are 180 degrees out of phase with each other. Thus, when light is entering along the optical channels 614, 620, the optical switch 612 is open and an output signal is provided. When light is input to only one of the channels 614 and 620, the optical switch 612 is closed and no output signal is provided. It will be appreciated that if no optical input is present on either channel 614, 620, no output signal is provided.

  Thus, according to the present invention, the digital signal light incident on the first and second data inputs is divided into two channels, one of which is shortened in wavelength and the phase is matched to the switch activation signal. Provide ANDGATE. In addition, activation light phase-matched to the shortened wavelength signal is incident on the optical switch and only opens and outputs a data signal from the gate when a data signal is received at both inputs, thereby causing the logic AND gate to A logical AND gate that satisfies the requirements is provided.

  Reference is now made to FIG. 22, which is a schematic diagram of a logical AND gate 630 that uses two optically active optical switches 632, 634 to process digital optical signal data. A first logic input signal that is 1500 nm light is provided to logic AND gate 630 along optical channel 636, and a second logic input signal that is 1500 nm light is provided to logic AND gate 630 along optical channel 638. Is done. A first optical channel 640, such as an optical fiber, provides a 1500 nm light drive signal to the optical switch 632, and a second optical channel 642 provides a 1500 nm light drive signal to the optical switch 634.

  The first and second wavelength reducers 642 and 646 double the frequency of the 1500 nm light so that the 1500 nm light becomes 750 nm light. After the frequency is doubled, the light output is boosted to a level necessary to activate the light activated optical switch. The optical switch is designed to be activated with an activated light output of 150 milliwatts. Half of the digital optical signal output along optical channel 647 by wavelength reducers 642, 646 is provided to optical absorber 648. The other half of the optical signal output from the wavelength reducers 642, 646 is coupled to the optical signal input on the optical channel 640 necessary to operate the logic AND gate 630. The optical switch 632 can pass the 1500 nm signal on the optical channel 640 until a 750 nm signal strong enough to close the optical switch 632 is input to the optical channel 650. This occurs when a 1500 nm signal is incident on the gates on the optical channels 636, 638. Optical channel 652 provides the output signal of switch 632 to wavelength reducer 654. The wavelength reducer 654 doubles the frequency of the 1500 nm signal along the optical channel 652 output by the optical switch 632.

  Optical channel 642 provides a 1500 nm signal to logic AND gate 630 and couples the 1500 nm signal to the output of wavelength reducer 654. The optical switch 634 can emit a 1500 nm signal from the optical channel 642 from the switch as long as no signal is output from the optical switch 632 via the wavelength reducer 654.

  If there is only a signal incident on one of the optical channels 636 and 638, the 750 nm signal input to the optical switch 632 closes the switch 632 and blocks the 1500 nm light flow from the optical channel 640. Is not enough. When a signal is provided to the optical channels 636, 638, the signal is sufficient to turn off the 1500 nm signal from the optical channel 640. As long as the signal from the optical channel 640 is output from the switch 632, there is no signal provided from the optical switch 634.

  The source light from optical channel 640 is turned off by optical switch 632 only when a 1500 nm signal is provided on optical channels 636, 638, and only then the input provided by optical channel 642 is switched. Since output from 634, a logical AND gate is provided and 1500 nm light is output only when a 1500 nm signal is provided to the optical channels 636, 638. This logical AND gate operates as shown in Table 1.

It will be appreciated that the change to half the wavelength is only given as an example. Other wavelengths and means can also be used.
Accordingly, the present invention provides a logical AND gate in which the wavelengths of the two input signals are immediately shortened and divided to provide light for activating the optical switch. In addition, when a data signal is input to both inputs of a gate that transmits a data wavelength signal supplied to the second optical switch, a logical AND gate is provided in which the switch is driven by light having a reduced wavelength. . The wavelength of the output signal ensures that the data signal is output from the logical AND gate only when two inputs are incident on the two data ports of the gate, thereby satisfying the requirements of the logical AND gate. Is increased to be a drive signal for the optical switch.

  Reference is now made to FIG. 23, which is a schematic diagram of a logical OR gate 700. FIG. A first logic input signal that is 1500 nm light is provided to the logic OR gate 700 along the optical channel 702, and a second logic input signal that is 1500 nm light is provided to the logic AND gate 700 along the optical channel 704. The The optical channel 706 provides 750 nm light supplied to the optical switch 708. The optical switch 708 can remain closed and no 1500 nm output signal is provided unless the 750 nm signal from the optical channel 706 is canceled.

  The first and second wavelength reducers 710, 712 double the frequency of the 1500 nm signals provided along the optical channels 702, 704 so that the 1500 nm signals become 750 nm signals. The optical power lost due to the frequency change is boosted by the optical amplifier integrated in the device, again to a useful level.

  The optical channel 714 carries the 750 nm signal output from the wavelength reducer 710 to the phase matcher 716. The phase matcher 716 brings the phase of the 750 nm signal along the optical channel 714 into phase with the phase of the 750 nm light source signal along the optical channel 706.

  Optical channel 718 provides the output from wavelength reducer 712 to phase matcher 720. The phase matcher 720 makes the phase of the signal along the optical channel 718 in phase with the phase of the 750 nm light source signal along the optical channel 706.

  Optical channels 722 and 724 provide half of the light from phase matcher sections 16 and 720 to light absorbers 726 and 728, respectively. The optical phase shifter 730 is a half-wave path that causes the signals from the optical channels 702, 704 to be 180 degrees out of phase with the light along the specially phase-matched optical channel 706. When these lights are mixed with the light along the optical channel 706, half of it will cancel out.

  Optical channel 732 carries the 750 nm source light from phase matcher 720 and couples it to the signals from optical phase shifter 730 and optical channel 740. The optical channel 740 is a source of 1500 nm light that exits the switch 708 until a signal of sufficient optical power incident from the optical channel 706 blocks the switch 708. The signal is output from switch 708 along optical channel 742, thus providing a logical OR gate.

  As long as the source of 750 nm light from the optical channel 706 is supplied to the switch 708, the signal from the 1500 nm light source from the optical channel 740 will not exit the logical OR gate, but the optical channels 702, 704 When a signal enters one of them, the light output from the optical channel 706 is canceled by half, and a 1500 nm signal appears from the logic OR gate.

  In addition, when signals are provided to the optical channels 702, 704, the combined optical output is sufficient to cancel the entire 750nm light source from the optical channel 706, resulting in a logic OR gate 700. An output signal is provided.

  The last paragraph explains how the logical OR gate disclosed herein meets the requirements of the logical OR gate truth table shown in Table 2. When a signal is provided along one or both of the optical channels 702, 704, a 1500 nm signal emerges from the logic OR gate 700.

By providing the logic not gate described in FIG. 20 to the output part of the logic OR gate described in FIG. 23, the logic NOR gate functioning as the truth table shown in Table 3 is configured.
Reference is now made to FIG. 24 which is a schematic diagram of an alternative logic OR gate 800. Transmission lines 802, 804 are optical channels or fibers that provide optical digital signals A and B incident on the gate. These signals are 1500 nm optical signals. Transmission lines 806 and 807 are 1500 nm light sources for the function of a logical OR gate.

  Although the wavelength reducers 808 and 810 are frequency doublers, they not only double the frequency but then boost the light output of the light to a level that can activate the light activated optical switch. . Transmission line 812 is a network of optical channels or fibers that carry signals A, B from wavelength reducers 808, 810, combine them with signals from transmission line 806, and carry all of these to optical output limiter 814.

  The light output limiter 814 allows passage of light output levels below a certain maximum level. The transmission line numbered 818 is an optical channel or fiber that carries the signal from the optical power limiter 814 to the switch 816 and from the switch 816 to the wavelength reducer 820. The switch 816 is a light activated optical switch. The wavelength reducer 820 doubles the frequency of the signal appearing from the switch 816.

  The switch 830 is a light activated optical switch. Transmission line 807 is an optical channel or fiber that provides a 1500 nm signal to be coupled to the output of wavelength reducer 820 to carry to switch 830. As long as the signal from the wavelength reducer 820 is present, no signal will appear from the switch 830.

  When a 1500 nm signal (A signal) enters from the transmission line 802, the signal is converted into 750 nm light in the reducer 808, passes through the optical output limiter 814 as it is, and is transmitted within the switch 816. Turn off the 1500 nm signal from 806. Therefore, since there is no signal for turning off the signal from the transmission line 807, the OR gate outputs a signal. When a signal (B signal) is input from the transmission line 804 and passes through the reducer 810 (doubling the frequency) and the optical output limiter 814 and reaches the switch 816, the signal from the switch 830 for turning off the switch 830 is output. There is no signal. Thus, the signal from transmission line 807 can exit the gate through switch 830.

  When signals from the transmission lines 802 and 804 are input, the two outputs of the reducers 808 and 810 are limited by the limiter 814 in order to make the signal from the transmission line 806 an appropriate signal to cut off at the switch 816. Is done. Thus, the signal from transmission line 807 can leave the logical OR gate. When a signal is input to either or both A and B, a 1500 nm signal appears from the logic OR gate. This functions as a truth table shown in Table 2 describing the function of the logical OR gate.

  A logic gate providing an OR function, wherein the at least one optical switch includes first and second optical switches, and the logic gate having a wavelength longer than the wavelength of the activation light receives the signal light input. First and second logic inputs; a first wavelength corrector that operates to reduce the wavelength of light along the first light input to the wavelength of the activation light; and the light along the second light input. A second wavelength corrector that operates to shorten the wavelength to the wavelength of the activation light; and first and second optical paths that provide wavelength corrected light from the first and second wavelength correctors; , Receiving light from the first wavelength corrector and the second wavelength corrector via corresponding first and second optical paths, and converting the light output from the first and second optical paths to a predetermined optical output level. The optical output limiter that operates to maintain the optical output limit and the optical output limiter from the optical output limiter A third optical path that supplies the received light to the first optical switch, and a third optical path that receives the signal light from the first optical switch and operates to shorten the wavelength of the received light to the wavelength of the activation light And a fourth optical path for supplying light from the third wavelength corrector to the second optical switch.

  Reference is now made to FIG. 25, which is a schematic diagram of a logical OR gate 900. FIG. Optical channel 902 provides a first input to logic gate 900. An optical channel is an optical fiber channel that carries an optical signal to a logic gate and is divided in half by the logic gate. Half of the light is input to the frequency increasing device numbered 905. This light is delivered from the frequency enhancement device 905 to a half-wave path numbered 906, the light from 905 is out of phase with respect to the light from the frequency enhancement device 908, and the frequency enhancement device 908. Meet the light from. The light from half-wave path 906 is then combined with the logic gate light and enters optical switch 910. The other half of the light from the transmission line 902 that is the logic input A is coupled to the other light of the logic gate and enters the optical switch 910. Transmission line 904 is input B to the logic gate. The transmission line 904 is an optical fiber channel that carries an optical signal to the logic gate, and is divided in half by the logic gate. Half of the light is input to the frequency enhancement device numbered 908. The light from the frequency increasing device numbered 908 is then combined with the other light in the logic gate and enters the optical switch numbered 910. The other half of the light from transmission line 904 is coupled to the other light of the logic device and enters optical switch 910. A transmission line 912 is an output of the logical OR device.

  A logic gate providing an OR function, wherein at least one optical switch comprises a single optical switch, and the logic gate having a signal light having a wavelength longer than the wavelength of the activating light, the first and second logic gates receiving the signal light A second optical input, a first optical path for receiving a first portion of the signal light received at the first logical input, and a second for receiving a second portion of the signal light received at the first logical input. A light path, a third light path for receiving a first portion of the signal light received at the second logic input, and a fourth light path for receiving a second portion of the signal light received at the second logic input. A first wavelength corrector that operates to shorten the wavelength of the light along the second optical path to the wavelength of the activating light, and the wavelength of the light along the fourth optical path is the wavelength of the activating light. A second wavelength corrector that operates to shorten to a first wavelength corrector, An optical phase shifter that operates to cause the wavelength correction light to be 180 degrees out of phase with respect to the light from the second wavelength corrector, and the optical switch includes first and third optical paths, Light is received from the second wavelength modifier and optical phase shifter.

  The logical NOR gate functioning as the truth table shown in Table 3 is constructed by arranging the logical NOT gate of FIG. 20 at the output of the logical OR gate of FIG. Although several embodiments of the logic gate using the photoactive optical switch have been described, other than the AND logic gate, the OR logic gate, the NOR logic gate, and the NOT logic gate using the photoactive optical switch. It is also possible to make this embodiment.

  As will be appreciated by those skilled in the art, the present invention is not limited to what is shown and described above in the figures. The present invention encompasses various features described above, and combinations and sub-combinations of modifications not possible in the prior art that are possible to those skilled in the art upon reading the above description.

Claims (5)

A logic gate providing an AND function,
A single optical switch activated by light,
An activation light and a signal light path having a variable cross-sectional area, which is configured to pass the activation light and a signal light having a longer wavelength than the activation light;
An activation light responsive piezoelectric element provided in association with the signal light path and operating to change shape in response to the activation light, wherein the signal light is changed by changing the shape of the piezoelectric element. An optical switch comprising an activated light-responsive piezoelectric element that operates to sufficiently change the variable cross-sectional area of a path and control the passage of the signal light along the signal light path;
An optical path for supplying signal light carrying digital information to and from the optical switch and supplying the activation light to the optical switch;
First and second logic inputs for receiving signal light;
A first optical path for receiving a first portion of the signal light received at the first logic input;
A second optical path for receiving a second portion of the signal light received at the first logic input;
A third optical path for receiving a first portion of the signal light received at the second logic input;
A fourth optical path for receiving a second portion of the signal light received at the second logic input;
A first wavelength corrector that operates to shorten the wavelength of light along the second optical path to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of light along the fourth optical path to the wavelength of the activation light;
A first phase matcher that operates to match the phase of the light along the second light path to the phase of the activation light;
A second phase matcher that matches the phase of the light along the fourth optical path to the phase of the activation light;
The wavelength-shortened and phase-matched light along the second optical path and the wavelength-shortened and phase-matched light along the fourth optical path operate to be 180 degrees out of phase with each other. An optical phase shifter,
The light along the first optical path and the third optical path is applied as signal light input to the optical switch, and is along the second optical path and the fourth optical path. The phase-matched light is shortened in wavelength, and the phase of the light along the second optical path matches the phase of the light along the second optical path and the phase of the light along the fourth optical path. A logic gate supplied to the optical switch as activation light together with the activation light whose phase is matched with the phase . A logic gate providing an AND function,
A first optical switch and a second optical switch, each optical switch comprising:
An activation light and a signal light path having a variable cross-sectional area, which is configured to pass the activation light and a signal light having a longer wavelength than the activation light;
An activation light responsive piezoelectric element provided in association with the signal light path and operating to change shape in response to the activation light, wherein the signal light is changed by changing the shape of the piezoelectric element. A first optical switch and a second optical switch, each of which comprises an activation photoresponsive piezoelectric element that operates to sufficiently change the variable cross-sectional area of the passage and control the passage of the signal light along the signal light passage. With an optical switch,
Supplying the activation light to the first optical switch and the second optical switch;
An optical path for transmitting signal light carrying digital information to and from these optical switches;
First and second logic inputs for receiving signal light inputs;
A first wavelength corrector that operates to shorten the wavelength of the signal light of the first input to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of the signal light of the second input to the wavelength of the activation light;
A third wavelength corrector that operates to shorten the wavelength of the signal light from the first optical switch;
A first light path for supplying a portion of the light from the first wavelength modifier to a first light absorber;
A second optical path for supplying a portion of the light from the first wavelength modifier to the first optical switch;
A third light path for supplying a portion of the light from the second wavelength modifier to a second light absorber;
A fourth optical path for supplying a portion of the light from the second wavelength modifier to the first optical switch;
A fifth optical path for supplying signal light from the first optical switch to the third wavelength modifier;
A logic gate comprising: a sixth optical path for supplying the wavelength-corrected light from the third wavelength corrector as activation light to the second optical switch; A logic gate providing an OR function,
A single optical switch activated by light,
An activation light and a signal light path having a variable cross-sectional area, which is configured to pass the activation light and a signal light having a longer wavelength than the activation light;
An activation light responsive piezoelectric element provided in association with the signal light path and operating to change shape in response to the activation light, wherein the signal light is changed by changing the shape of the piezoelectric element. An optical switch comprising an activated light-responsive piezoelectric element that operates to sufficiently change the variable cross-sectional area of a path and control the passage of the signal light along the signal light path;
An optical path for supplying signal light carrying digital information to and from the optical switch and supplying the activation light to the optical switch;
First and second logic inputs for receiving signal light inputs;
A first wavelength corrector that operates to shorten the wavelength of the signal light along the first optical input to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of light along the second light input to the wavelength of the activation light;
A first phase matcher that operates to match the phase of the wavelength corrected light from the first wavelength corrector to the phase of the activation light;
A second phase matcher that operates to match the phase of the light from the second wavelength modifier to the phase of the activation light;
A first optical path for supplying a portion of the light from the first phase matcher to a first light absorber;
A second optical path for supplying a portion of the light from the second phase matcher to a second light absorber;
A first optical phase shifter;
A second optical phase shifter;
Supplying a portion of the light from the first phase matcher to the first optical phase shifter, thereby causing the light from the first phase matcher to be out of phase with respect to the activation light; And a part of the light from the second phase matcher is supplied to a second optical phase shifter, whereby the light from the first phase matcher is activated to supply A fourth optical path that is out of phase with respect to the quantized light
A fifth optical path for supplying light from the first optical phase shifter to the optical switch;
A sixth optical path for supplying light from the second optical phase shifter to the optical switch, and the optical switch receives the activation light and signal light from the fifth and sixth optical paths. Receiving logic gate. A logic gate providing an OR function,
A first optical switch and a second optical switch, each optical switch comprising:
An activation light and a signal light path having a variable cross-sectional area, which is configured to pass the activation light and a signal light having a longer wavelength than the activation light;
An activation light responsive piezoelectric element provided in association with the signal light path and operating to change shape in response to the activation light, wherein the signal light is changed by changing the shape of the piezoelectric element. A first optical switch and a second optical switch, each of which comprises an activation photoresponsive piezoelectric element that operates to sufficiently change the variable cross-sectional area of the passage and control the passage of the signal light along the signal light passage. With an optical switch,
An optical path for supplying the activation light to the first optical switch and the second optical switch and for transmitting signal light carrying digital information to and from these optical switches;
First and second logic inputs for receiving signal light inputs;
A first wavelength corrector that operates to shorten the wavelength of light along the first light input to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of light along the second light input to the wavelength of the activation light;
First and second optical paths for supplying wavelength-corrected light from the first and second wavelength correctors;
An optical output limiter that receives light from the first wavelength corrector and the second wavelength corrector via the first and second optical paths, respectively, and outputs a light output from the limiter to a predetermined value. An optical output limiter that operates to maintain the optical output level;
A third optical path for supplying the first optical switch with light output from the optical output limiter;
A third wavelength corrector that receives the signal light from the first optical switch and operates to shorten the wavelength of the received signal light to the wavelength of the activation light;
A logic gate comprising: a fourth optical path for supplying light from the third wavelength modifier to the second optical switch. A logic gate providing an OR function,
A single optical switch activated by light,
An activation light and a signal light path having a variable cross-sectional area, which is configured to pass the activation light and a signal light having a longer wavelength than the activation light;
An activation light responsive piezoelectric element provided in association with the signal light path and operating to change shape in response to the activation light, wherein the signal light is changed by changing the shape of the piezoelectric element. An optical switch comprising an activated light-responsive piezoelectric element that operates to sufficiently change the variable cross-sectional area of a path and control the passage of the signal light along the signal light path;
An optical path for supplying signal light carrying digital information to and from the optical switch and supplying the activation light to the optical switch;
First and second logic inputs for receiving signal light;
A first optical path for receiving a first portion of the signal light received at the first logic input;
A second optical path for receiving a second portion of the signal light received at the first logic input;
A third optical path for receiving a first portion of the signal light received at the second logic input;
A fourth optical path for receiving a second portion of the signal light received at the second logic input;
A first wavelength corrector that operates to shorten the wavelength of light along the second optical path to the wavelength of the activation light;
A second wavelength corrector that operates to shorten the wavelength of light along the fourth optical path to the wavelength of the activation light;
An optical phase shifter that operates to cause the wavelength corrected light from the first wavelength corrector to be 180 degrees out of phase with the light from the second wavelength corrector; A logic gate in which a switch receives light from the first and third optical paths, the second wavelength modifier, and the optical phase shifter.

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