Optical signal processor

• US 6,556,335 B2
• Filed: 08/30/2001
• Issued: 04/29/2003
• Est. Priority Date: 08/31/2000
• Status: Expired due to Term

• Current Assignee: Alcatel-Lucent SA (Nokia Corporation)
• Original Assignee: Alcatel SA (Nokia Corporation)
• Inventors: Simeonidou, Dimitra, Lee, Heng Loong
• Primary Examiner(s): Mai, Huy
• Assistant Examiner(s): TRA, TUYEN Q
• Application Number:
  US09/941,662
• Publication Number:
  US 20020024707A1
• Time in Patent Office: 607 Days
• Field of Search: 359/238, 359/110, 359/140, 359/181, 359/115, 359/124
• US Class Current: 359/238
• CPC Class Codes: H04B 10/299 Signal waveform processing, e.g. reshaping or retiming
• CPC Class Codes: H04B 2210/258 treating each wavelength or wavelength band separately

Abstract

The present invention provides an optical signal processor for the optical processing of a digitally amplitude-modulated optical signal input thereto, to determine the presence or absence of a predetermined digital bit-pattern within said optical signal.

Claims

1. An optical signal processor for the optical processing of a digitally amplitude-modulated optical signal input thereto, to determine the presence or absence of a predetermined digital bit-pattern within said optical signal, the optical signal processor possessing optical processing means including;

signal duplicating means operable to derive from said input digital optical signal one or more duplicate digital optical signals which are each a duplicate of the digital bit-patterns present within the input optical signal;

signal duplicating and inverting means operable to derive from said input digital optical signal one or more polarity-inverted duplicate digital optical signals, the polarity of each bit of which is the inverse of that of the signal bit from which it is derived, wherein;

the optical processing means is operable to derive from said duplicate signals and said polarity-inverted duplicate signals an optical detection signal which indicates the presence or absence of said predetermined amplitude-modulated digital bit-pattern within the input digital signal processed thereby.

2. An optical signal processor according to claim 1 wherein the optical processing means further includes optical transmission delay means and is operable to transmit through said delay means said duplicate signals and said polarity-inverted duplicate signals derived from said input digital optical signal, wherein;

the optical processing means is operable to derive said optical detection signal from a combination of said duplicate signals and said polarity-inverted duplicate signals output of said optical delay means.

3. An optical signal processor according to claim 2 wherein the optical delay means includes a plurality of separate optical transmission delay lines the optical transmission delay provided by each one of which is determined by the length thereof.

4. An optical signal processor according to claim 2 wherein the optical processing means includes optical combining means for combining in equal proportion the delayed duplicate and polarity-inverted duplicate signals output from each one of said transmission delay means so as to thereby derive said optical detection signal.

5. An optical signal processor according to claim 4 wherein the combining means is an optical combiner.

6. An optical signal processor according to claim 2 wherein the optical processing means includes a plurality of separate optical transmission delay means and is operable to transmit respective ones of said duplicate signals and said polarity-inverted duplicate signals through respective individual ones of the separate optical delay means, wherein;

the optical processing means is operable to derive said optical detection signal from a combination of the delayed duplicate signals and delayed polarity-inverted duplicate signals output of said optical delay means.

7. An optical signal processor according to claim 6 wherein the optical transmission delay provided by each one of said transmission delay means differs from that provided by any of the other transmission delay means by an amount equal to an integer multiple of the optical bit period associated with said predetermined amplitude-modulated digital bit-pattern.

8. An optical signal processor according to claim 6 wherein the optical processing means includes signal routing means operable to direct respective ones of said duplicate signals and said polarity-inverted duplicate signals input thereto to respective individual ones of said separate optical delay means in dependance upon the wavelength of the radiation conveying each respective duplicate signal.

9. An optical signal processor according to claim 8 wherein the signal routing means is an optical de-multiplexer.

10. An optical signal processor according to claim 9 wherein the signal routing means is an arrayed-waveguide (AWG) optical de-multiplexer.

11. An optical signal processor according to claim 1 wherein said signal duplicating means and said signal duplicating and inverting means are operable to produce one or more duplicate signals (polarity-inverted or otherwise) each one of which is conveyed via optical radiation of a wavelength different from that of the radiation conveying any of the other signal duplicates produced thereby.

12. An optical signal processor according to claim 1 wherein the signal duplicating and inverting means includes a semiconductor optical amplifier (SOA) operable, via the process of Cross-Gain Modulation, to output an optical signal which is the polarity-inverted duplicate of optical signal radiation input thereto.

13. An optical signal processor according to claim 1 wherein the signal duplicating means includes two concatenated semiconductor optical amplifiers (SOA) each operable, via the process of Cross-Gain Modulation, to output an optical signal which is the polarity-inverted duplicate of optical signal radiation input thereto.

14. An optical signal processor according to claim 1 wherein the optical signal processor is operable to partition optical signal radiation input thereto into two portions and to transmit a first such portion via said optical processing means, to a first optical output port thereof and to transmit the second such portion via an optical transmission delay line, to a second optical output of the optical signal processor wherein;

the transmission delay provided by said delay line is such as to permit substantially simultaneous arrival of the optically processed first portion and the delayed second portion at said first and second optical output ports.

25. A method for the optical processing of a digitally amplitude-modulated optical signal according to any preceding

claim including the further steps of;

partitioning optical signal radiation input thereto into two portions and optically processing a first of said two portions and transmitting said second such portion via an optical transmission delay line, wherein;

the transmission delay of said second portion is substantially equal to the delay associated with the optical processing of said first portion.

15. An optical signal processor for the optical processing of a digitally amplitude-modulated optical signal input thereto, to determine the presence or absence of a predetermined digital bit-pattern within said optical signal, the optical signal processor possessing optical processing means including;

signal duplicating means operable to derive from said input digital optical signal one or more duplicate digital optical signals which are each a duplicate of the digital bit-patterns present within the input optical signal;

signal duplicating and inverting means operable to derive from said input digital optical signal one or more polarity-inverted duplicate digital optical signals, the polarity of each bit of which is the inverse of that of the signal bit from which it is derived, wherein;

the optical processing means is operable to derive from said duplicate signals and said polarity-inverted duplicate signals an optical detection signal which indicates the presence or absence of said predetermined amplitude-modulated digital bit-pattern within the input digital signal processed thereby,

wherein the optical processing means further includes optical transmission delay means and is operable to transmit through said delay means said duplicate signals and said polarity-inverted duplicate signals derived from said input digital optical signal, wherein;

the optical processing means is operable to derive said optical detection signal from a combination of said duplicate signals and said polarity-inverted duplicate signals output of said optical delay means,

wherein said signal duplicating means and said signal duplicating and inverting means are operable to produce one or more duplicate signals (polarity-inverted or otherwise) each one of which is conveyed via optical radiation of a wavelength different from that of the radiation conveying any of the other signal duplicates produced thereby,

wherein the optical processing means includes a plurality of separate optical transmission delay means and is operable to transmit respective ones of said duplicate signals and said polarity-inverted duplicate signals through respective individual ones of the separate optical delay means, wherein;

the optical processing means is operable to derive said optical detection signal from a combination of the delayed duplicate signals and delayed polarity-inverted duplicate signals output of said optical delay means,

wherein the optical transmission delay provided by each one of said transmission delay means differs from that provided by any of the other transmission delay means by an amount equal to an integer multiple of the optical bit period associated with said predetermined amplitude-modulated digital bit-pattern.

16. A method for the optical processing of a digitally amplitude-modulated optical signal so as to determine the presence or absence of a predetermined digital bit-pattern therein, the optical signal processing method including the steps of;

deriving from said digital optical signal one or more duplicate digital optical signals which are each a duplicate of the digital bit-patterns present within the optical signal;

deriving from said digital optical signal one or more polarity-inverted duplicate digital optical signals, the polarity of each bit of which is the inverse of that of the signal bit from which it is derived;

deriving from said duplicate signals and said polarity-inverted duplicate signals an optical detection signal which indicates the presence or absence of said predetermined amplitude-modulated digital bit-pattern within the digital optical signal.

17. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 16 further including the step of transmitting through an optical transmission delay means said duplicate signals and said polarity-inverted duplicate signals derived from said digital optical signal, and;

deriving said optical detection signal from a combination of said duplicate signals and said polarity-inverted duplicate signals output of said optical delay means.

18. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 17 wherein respective ones of said duplicate signals and said polarity-inverted duplicate signals are transmitted through respective individual ones of a plurality of separate optical transmission delay means, wherein;

said optical detection signal is derived from a combination of the delayed duplicate signals and the delayed polarity-inverted duplicate signals output of said optical delay means.

19. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 18 wherein each one of said separate transmission delay means provides a transmission delay which differs from that provided by any of the other transmission delay means by an amount equal to an integer multiple of the optical bit period associated with said predetermined amplitude-modulated digital bit-pattern.

20. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 18 wherein respective ones of said duplicate signals and said polarity-inverted duplicate signals are directed to respective individual ones of said separate optical delay means in dependance upon the wavelength of the radiation conveying each respective duplicate signal.

21. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 17 including the step of combining in equal proportion the delayed duplicate and polarity-inverted duplicate signals output from each one of said transmission delay means so as to thereby derive said optical detection signal.

22. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 16 wherein said duplicate signals and said polarity-inverted duplicate signals are each conveyed via optical radiation of a wavelength different from that of the radiation conveying any of the other signal duplicates.

23. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 16 wherein the signal duplicating and inverting is provided via the process of Cross-Gain Modulation of a semiconductor optical amplifier (SOA) operable to output an optical signal which is the polarity-inverted duplicate of optical signal radiation input thereto.

24. A method for the optical processing of a digitally amplitude-modulated optical signal according to claim 16 wherein signal duplicating is provided via the process of Cross-Gain Modulation two concatenated semiconductor optical amplifiers (SOA) each operable to output an optical signal which is the polarity-inverted duplicate of optical signal radiation input thereto.

26. A method for the optical processing of a digitally amplitude-modulated optical signal so as to determine the presence or absence of a predetermined digital bit-pattern therein, the optical signal processing method including the steps of;

deriving from said digital optical signal one or more duplicate digital optical signals which are each a duplicate of the digital bit-patterns present within the optical signal;

deriving from said digital optical signal one or more polarity-inverted duplicate digital optical signals, the polarity of each bit of which is the inverse of that of the signal bit from which it is derived;

deriving from said duplicate signals and said polarity-inverted duplicate signals an optical detection signal which indicates the presence or absence of said predetermined amplitude-modulated digital bit-pattern within the digital optical signal,

further including the step of transmitting through an optical transmission delay means said duplicate signals and said polarity-inverted duplicate signals derived from said digital optical signal, and;

deriving said optical detection signal from a combination of said duplicate signals and said polarity-inverted duplicate signals output of said optical delay means,

wherein said duplicate signals and said polarity-inverted duplicate signals are each conveyed via optical radiation of a wavelength different from that of the radiation conveying any of the other signal duplicates, and

wherein respective ones of said duplicate signals and said polarity-inverted duplicate signals are transmitted through respective individual ones of a plurality of separate optical transmission delay means, wherein;

said optical detection signal is derived from a combination of the delayed duplicate signals and the delayed polarity-inverted duplicate signals output of said optical delay means.