ALL-OPTICAL LOGIC GATES USING NONLINEAR ELEMENTS - CLAIM SET V

• US 20090154887A1
• Filed: 02/19/2009
• Published: 06/18/2009
• Est. Priority Date: 02/14/2006
• Status: Active Grant

• Current Assignee: John Covey
• Original Assignee: CoveyTech, LLC
• Inventors: Covey, John Luther
• Granted Patent: US 7,720,339 B2
• Time in Patent Office: Days
• US Class Current: 385/122
• CPC Class Codes: G02F 2202/32 Photonic crystals
• CPC Class Codes: G02F 2203/15 involving resonance effects, e.g. resonantly enhanced interaction
• CPC Class Codes: G02F 3/024 based on non-linear elements, e.g. non-linear Fabry-Perot cavity G02F3/028 takes precedence

Abstract

An all-optical logic gates comprises a nonlinear element such as an optical resonator configured to receive optical input signals, at least one of which is amplitude-modulated to include data. The nonlinear element is configured in relation to the carrier frequency of the optical input signals to perform a logic operation based on the resonant frequency of the nonlinear element in relation to the carrier frequency. Based on the optical input signals, the nonlinear element generates an optical output signal having a binary logic level. A combining medium can be used to combine the optical input signals for discrimination by the nonlinear element to generate the optical output signal. Various embodiments include all-optical AND, NOT, NAND, NOR, OR, XOR, and XNOR gates and memory latch.

Claims

1. An all-optical XOR gate comprising:

first and second optical input media for receiving respective first and second amplitude-modulated optical input signals, the first and second amplitude-modulated optical input signals having respective data with binary logic levels;

a combining medium optically coupled to the first and second optical input media, the combining medium configured to receive and combine the first and second optical input signals to produce a combined signal;

a nonlinear element configured to receive the combined signal, the nonlinear element having an optical resonator with a resonant frequency tuned relative to the frequency of at least one of the first and second optical input signals so that the nonlinear element outputs light as an optical output signal with a high logic level only if the combined signal results from only one of the first and second optical input signals having a high logic level, and the nonlinear element outputs substantially no light as the optical output signal with a low logic level if the combined signal results from both of the optical input signals having high or low logic levels, the optical output signal thus having a binary logic level that is amplitude-modulated; and

an optical output medium optically coupled to receive and output the optical output signal from the nonlinear element,

the first and second optical input media, combining medium, nonlinear element and optical output medium formed in a photonic crystal,

the first and second optical input media, the combining medium, and the optical output medium defined by the absence of structures in the photonic crystal,

the nonlinear element optically positioned between an output side of the combining medium and an input side of the optical output medium.

2. An all-optical XOR gate as claimed in claim 1 wherein an output side of the combining medium and an input side of the optical output medium are optically aligned with one another.

3. An all-optical XOR gate as claimed in claim 1 wherein the nonlinear element is defined by first and second sets of spaced structures bounding a region with an absence of structures to define a cavity.

4. An all-optical XOR gate as claimed in claim 3 wherein the first and second sets of spaced structures each include a plurality of structures of varying size.

5. An all-optical XOR gate as claimed in claim 1 wherein the photonic crystal comprises silicon.

6. An all-optical XOR gate as claimed in claim 1 wherein the photonic crystal comprises gallium arsenide (GaAs).

7. An all-optical XOR gate as claimed in claim 1 wherein the photonic crystal comprises a silicon-on-insulator (SOI) structure.

8. An all-optical XOR gate as claimed in claim 1 wherein the photonic crystal is an optical chip.

9. An all-optical XOR gate as claimed in claim 8 wherein the optical chip is mounted to a bridge.

10. An all-optical XOR gate as claimed in claim 1 further comprising:

a first optical fiber optically coupled to an input side of the first optical input medium to guide the first optical input signal to the first optical input medium.

11. An all-optical XOR gate as claimed in claim 10 further comprising:

a second optical fiber optically coupled to an input side of the second optical input medium to guide the second optical input signal to the second optical input medium.

12. An all-optical XOR gate as claimed in claim 10 wherein the structures of the photonic crystal taper at the input side of the first optical input medium.

13. An all-optical XNOR gate comprising:

first and second optical input media for receiving respective first and second amplitude-modulated optical input signals, the first and second amplitude-modulated optical input signals having respective data with binary logic levels;

a first combining medium optically coupled to the first and second optical input media, the first combining medium configured to receive and combine the first and second optical input signals to produce a first combined signal;

a nonlinear element configured to receive the combined signal, the nonlinear element having an optical resonator with a resonant frequency tuned relative to the frequency of at least one of the first and second optical input signals so that the nonlinear element outputs light as an optical output signal with a high logic level only if the combined signal results from only one of the first and second optical input signals having a high logic level, and the nonlinear element outputs substantially no light as the optical output signal with a low logic level if the combined signal results from both of the optical input signals having high or low logic levels, the optical output signal thus having a binary logic level that is amplitude-modulated;

a first optical output medium optically coupled to receive and output the first optical output signal from the first nonlinear element;

third and fourth optical input media for receiving a constant continuous wave (CW) light as a third optical input signal and optically coupled to receive the first optical output signal as a fourth optical input signal, respectively;

a second combining medium optically coupled to the third and fourth media, the second combining medium configured to receive and combine the third and fourth optical input signals to produce a second combined signal;

a second nonlinear element configured to receive the second combined signal, the second nonlinear element having an optical resonator with a resonant frequency tuned relative to the frequency of at least one of the third and fourth optical input signals so that the second nonlinear element outputs light as a second optical output signal with a high logic level having the amplitude of the CW light if the combined signal results from the fourth optical input signal having a low logic level, and the second nonlinear element outputs substantially no light as the second optical output signal if the combined signal results from the fourth optical input signal having a high logic level, the second optical output signal thus having a binary logic level that is amplitude-modulated with the amplitude of the high logic level determined substantially by the amplitude of the CW light; and

a second optical output medium optically coupled to receive and output the second optical output signal from the second nonlinear element as the output of the XNOR gate,

the first, second, third and fourth optical input media, first and second combining media, first and second nonlinear elements and first and second optical output media formed in a photonic crystal,

the first, second, third and fourth optical input media, first and second combining media, and the first and second optical output media defined by the absence of structures in the photonic crystal,

the first nonlinear element optically positioned between an output side of the first combining medium and an input side of the first optical output medium, and

the second nonlinear element optically positioned between an output side of the second combining medium and the second optical output medium.

14. An all-optical XNOR gate as claimed in claim 13 wherein an output side of the first combining medium and an input side of the first optical output medium are optically aligned with one another.

15. An all-optical XNOR gate as claimed in claim 13 wherein an output side of the second combining medium and an input side of the second optical output medium are optically aligned with one another.

16. An all-optical XNOR gate as claimed in claim 13 wherein the first nonlinear element is defined by first and second sets of spaced structures bounding a region with an absence of structures to define a cavity.

17. An all-optical XNOR gate as claimed in claim 16 wherein the first and second sets of spaced structures each include a plurality of structures of varying size.

18. An all-optical XNOR gate as claimed in claim 13 wherein the second nonlinear element is defined by first and second sets of spaced structures bounding a region with an absence of structures to define a cavity.

19. An all-optical XNOR gate as claimed in claim 18 wherein the first and second sets of spaced structures each include a plurality of structures of varying size.

20. An all-optical XNOR gate as claimed in claim 13 wherein the photonic crystal comprises silicon.

21. An all-optical XNOR gate as claimed in claim 13 wherein the photonic crystal comprises gallium arsenide (GaAs).

22. An all-optical XNOR gate as claimed in claim 13 wherein the photonic crystal comprises a silicon-on-insulator (SOI) structure.

23. An all-optical XNOR gate as claimed in claim 13 wherein the photonic crystal is an optical chip.

24. An all-optical XNOR gate as claimed in claim 23 wherein the optical chip is mounted to a bridge.

25. An all-optical XNOR gate as claimed in claim 13 further comprising:

a first optical fiber optically coupled to an input side of the first optical input medium to guide the first optical input signal to the first optical input medium.

26. An all-optical XNOR gate as claimed in claim 25 further comprising:

a second optical fiber optically coupled to an input side of the second optical input medium to guide the second optical input signal to the second optical input medium.

27. An all-optical XNOR gate as claimed in claim 25 wherein the structures of the photonic crystal taper at the input side of the first optical input medium.