British Telecommunications Public Limited Company

Corning Incorporated

Robert John Manning

Alistair James Poustie

Keith J Blow

Julian Kazimierz Lucek

Andrew David Ellis

Roderick Peter Webb

David M Spirit

David M Patrick

There is provided a two-stage optical regenerator for regenerating a data signal comprising a series of optical pulses. Each stage of the optical regenerator comprises a modulator for modulating a reference signal with an input signal, and an interferometer for causing the modulated reference signal to interfere with another version of the modulated reference signal delayed by less than one bit period of the data signal to regenerate the input signal. The input signal of the modulator of the first stage of the regenerator comprises the data signal, and the input signal of the modulator of the second stage of the regenerator comprises the output from the first stage of the regenerator. Relative phase offsets are induced at the outputs of the two interferometers of the regenerator to obtain either minimum transmission from each of the interferometers by the maximum power levels of the respective input signals transmitted therethrough, or maximum transmission from the interferometer of the first stage by the maximum power level of the data signal, and minimum transmission from the interferometer of the second stage by the minimum power level of the output from the first stage of the regenerator.

Optical regenerator

The present invention relates to an apparatus for determining the sum of first and second optical binary words. The apparatus uses a first optical logic gate and a second optical logic gate to generate respective first and second combination words which represent a logical combination of the binary words applied to the respective logic gates. The first and second combination words are then offset by one bit slot with respect to each other by an offsetting device to generate first and second offset combination words. These offset combination words are repeatedly fed back to the first and second logic gates. The binary sum of the original two words is given by the first combination word when each bit slot of the second combination words has the same logical state.

Binary adder

The present invention relates to a method and apparatus for generating an optical bit slot window in which N bit slots having the same logical state are generated. A switching device is used which is coupled to an optical pulse source which generates optical pulses in successive bit slots, each optical pulse representing a logical state. Switching signals are then applied to a switching input of the switching device so as to selectively switch a connection between the input and an output. Consequently the logical state of the output is controlled to generate the required N bit slot window.

Method of obtaining an optical signal stream

A parity determining circuit is used to determine the parity of a binary word. The binary word is represented by a sequence of optical bit slots. Each bit slot defines a respective one of two complementary logical states. The circuit includes: an input pulse stream generator that generates copies of the binary word; a combining device that receives two binary words, offsets one word with respect to the other, and then combines them to form a combination word; and a circuit that applies a copy of the original binary word together with the combination word to the combining device a number of times in succession. This results in a combination word that has a number of bits in the same logical state and that indicates the parity of the binary word.

Parity determining apparatus and method

A clock signal at a divided clock rate is obtained from an optical signal stream at a higher clock rate. The optical signal stream at the higher clock rate is applied to an all-optical non- linear gate. There is feedback from the first output of the gate to its control input. The optical signal at a divided clock rate is present at a second output of the gate. The gate may comprise a non-linear loop mirror. A number of such gates may be cascaded in series to provide an output at a clock rate divided by 2 , where is an integer.

Optical clock division

A regenerative optical memory comprising a number of concatenated non-linear switching elements coupled by an optical storage element has a transfer function arranged so that only optical data having a pulse amplitude above a predetermined threshold is stored and the amplitude of optical data stored is substantially equalised to at least one predetermined level after a number of circulations within the optical memory. In a preferred embodiment, the optical memory is provided with an optical switching element within the optical loop for selectively switching at least a portion of the data pattern out of the optical loop in response to the application of an optical signal to an input of the optical switching element to alter the contents of the memory.

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Ipswich, United Kingdom

Robert John Manning