These devices and Boolean logic are not limited to electronics. They have been demonstrated with optics in many different implementations with various switching mechanisms. The interest the optics community has in these devices has spawned from the fact that conventional computational speeds are approaching limits.
Optical logic gates can be made by using basic optical phenomena like, refraction, reflection, Interference, dispersion and absorption. Currently maximum optical gates are working in Non linear optics. This could also be made by using Electrooptic and accoustooptic crystals. this will provide very cheap and fast optical communication, since optical to electrical conversion will be removed for optical processing.
Few Optical gates are working with loop reflector, Machzender and Michelson intereferometer.
Optical NAND Gate could be made by using OLCR method in the optical domain, which is design by me.
For more detail contact me, I will reply for your questions.
Optical logic gates can be made by using basic optical phenomena like, refraction, reflection, Interference, dispersion and absorption. Currently maximum optical gates are working in Non linear optics. This could also be made by using Electrooptic and accoustooptic crystals. this will provide very cheap and fast optical communication, since optical to electrical conversion will be removed for optical processing.
Few Optical gates are working with loop reflector, Machzender and Michelson intereferometer.
Optical NAND Gate could be made by using OLCR method in the optical domain, which is design by me.
For more detail contact me, I will reply for your questions.
Optical gates can be made by two types:-
- By using Optical passive devices
- By using Optical active devices
BY Passive optical device, in this we can use the basic element like fiber couplers.
By Active optical devices, in this we use nonlinear material like etalon.
Interference
In this two waves are interacting each other and making interference, this is basic optical phenomenon. This will depend upon the frequencies and optical path difference of both beams.
Bi-stability
Bi-stable system is a system, which is stable in both two states, means changing of states from one states two other state is possible only when any input is applied to the input terminal, device will not change its any state automatically, which is very useful phenomenon. Since system is holding its state it could be considered as memory element and when we are applying input it is changing state according to input so it is working like a logic gate depending upon input not the time.
Two features required for making a bistable device: Non-linearity and Feedback. An optical bistable system can be realized by use of a nonlinear optical element, whose output beam is used in a feedback system to control the transmission of light trough the element itself.
Bistable Optical Devices
Numerous schemes can be used for the optical implementation of the foregoing basic principle. Two types of nonlinear optical elements can be used
Dissipative Nonlinear Element
A dissipative nonlinear material has an absorption coefficient that is dependent on the optical intensity I. The saturable absorber in which the absorption coefficient is nonlinear function of I,
Suppose that the saturable absorber is replaces by an amplifying medium with a saturable gain
The system is nothing but optical amplifier with feedback. In some sense, the dispersive bistable optical system is the nonlinear-index-of-refraction analog of the laser.
Optical And gate
In this method we use two pulses as input. The binary data is represented by pulses that are added and their sum used as input to bistable device. With and appropriate choice of the pulse height in relation to the threshold, the device can be made to switch to high only when both pulses are present, so that it act as an AND gate. The AND logic gate is a digital device with two binary inputs and one binary output. Both input must be in the "1" state for the output to be in the "1" state. Otherwise, the output will be "0" state.
\par this is as simple as addition of two signals and making threshold greater than both but less than summation of both signals.
all-optical reversible gates, namely, Feynman, Toffoli, Peres, and Feynman double gates, with optically controlled microresonators. To demonstrate the applicability, a bacteriorhodopsin protein-coated silica microcavity in contact between two tapered single-mode fibers has been used as an all-optical switch. Low-power control signals (<200 μW) at 532 nm and at 405 nm control the conformational states of the protein to switch a near infrared signal laser beam at 1310 or 1550 nm. This configuration has been used as a template to design four-port tunable resonant coupler logic gates. The proposed designs are general and can be implemented in both fiber-optic and integrated-optic formats and with any other coated photosensitive material. Advantages of directed logic, high Q-factor, tunability, compactness, low-power control signals, high fan-out, and flexibility of cascading switches in 2D/3D architectures to form circuits make the designs promising for practical applications.
Interference
In this two waves are interacting each other and making interference, this is basic optical phenomenon. This will depend upon the frequencies and optical path difference of both beams.
Bi-stability
Bi-stable system is a system, which is stable in both two states, means changing of states from one states two other state is possible only when any input is applied to the input terminal, device will not change its any state automatically, which is very useful phenomenon. Since system is holding its state it could be considered as memory element and when we are applying input it is changing state according to input so it is working like a logic gate depending upon input not the time.
Two features required for making a bistable device: Non-linearity and Feedback. An optical bistable system can be realized by use of a nonlinear optical element, whose output beam is used in a feedback system to control the transmission of light trough the element itself.
Bistable Optical Devices
Numerous schemes can be used for the optical implementation of the foregoing basic principle. Two types of nonlinear optical elements can be used
- Dispersive nonlinear element, for which the refractive index n is a function of optical intensity.
- Dissipative nonlinear element, for which the absorption coefficient alpha is a function of the optical intensity.
Dissipative Nonlinear Element
A dissipative nonlinear material has an absorption coefficient that is dependent on the optical intensity I. The saturable absorber in which the absorption coefficient is nonlinear function of I,
Suppose that the saturable absorber is replaces by an amplifying medium with a saturable gain
The system is nothing but optical amplifier with feedback. In some sense, the dispersive bistable optical system is the nonlinear-index-of-refraction analog of the laser.
Optical And gate
In this method we use two pulses as input. The binary data is represented by pulses that are added and their sum used as input to bistable device. With and appropriate choice of the pulse height in relation to the threshold, the device can be made to switch to high only when both pulses are present, so that it act as an AND gate. The AND logic gate is a digital device with two binary inputs and one binary output. Both input must be in the "1" state for the output to be in the "1" state. Otherwise, the output will be "0" state.
\par this is as simple as addition of two signals and making threshold greater than both but less than summation of both signals.
all-optical reversible gates, namely, Feynman, Toffoli, Peres, and Feynman double gates, with optically controlled microresonators. To demonstrate the applicability, a bacteriorhodopsin protein-coated silica microcavity in contact between two tapered single-mode fibers has been used as an all-optical switch. Low-power control signals (<200 μW) at 532 nm and at 405 nm control the conformational states of the protein to switch a near infrared signal laser beam at 1310 or 1550 nm. This configuration has been used as a template to design four-port tunable resonant coupler logic gates. The proposed designs are general and can be implemented in both fiber-optic and integrated-optic formats and with any other coated photosensitive material. Advantages of directed logic, high Q-factor, tunability, compactness, low-power control signals, high fan-out, and flexibility of cascading switches in 2D/3D architectures to form circuits make the designs promising for practical applications.
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