Optical signal processor

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.

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.