All optical logic using cross-phase modulation amplifiers and mach-zehnder interferometers with phase-shift devices

An interferometer logic gate comprising:

• splitter means, receiving a first optical signal, for generating an upper branch signal and a lower branch signal;
• upper semiconductor optical amplifier (SOA) means, receiving the upper branch signal, for adding a phase shift to the upper branch signal when a control optical signal is in a high power state, but for not adding the phase shift to the upper branch signal when the control optical signal is in a low power state;
• lower SOA means, receiving the lower branch signal, for buffering the lower branch signal;
• and
• combiner means, receiving the upper branch signal from the upper SOA means, and receiving the lower branch signal from the lower SOA means, for generating an upper and a lower output, the upper output resulting from constructive or destructive interference of the upper branch signal and a diagonal lower branch signal, while the lower output resulting from constructive or destructive interference of the lower branch signal and a diagonal upper branch signal, wherein the diagonal upper branch signal is the upper branch signal with an added phase shift while the diagonal lower branch signal is the lower branch signal with the added phase shift.

An optical NAND gate comprising:

• a continuous-wave input having a high power level;
• a power-increasing semiconductor optical amplifier (SOA), receiving the continuous-wave input, for increasing optical power of the continuous-wave input to generate a boosted signal having a boosted power greater than the high power level;
• a multi-mode interference (MMI) splitter, receiving the boosted signal, for generating four branch signals each having about one-quarter of the boosted power of the boosted signal;
• a first SOA, receiving a first branch signal of the four branch signals and receiving a first logic input, for adjusting a phase of a first optical output in response to the first logic input;
• a second SOA, receiving a second branch signal of the four branch signals, for generating a second optical output that matches a phase of the first optical output when the first SOA does not adjust the phase of the first optical output;
• a third SOA, receiving a third branch signal of the four branch signals and receiving a second logic input, for adjusting a phase of a third optical output in response to the second logic input;
• a fourth SOA, receiving a fourth branch signal of the four branch signals, for generating a fourth optical output that matches a phase of the third optical output when the third SOA does not adjust the phase of the third optical output;
• a combiner, receiving the first, second, third, and fourth optical outputs, for generating a combined output;
• and
• a power-restoring SOA, coupled to receive the combined output from the combiner, for generating a final output having about the high power level when the first logic input is not at the high power level and the second logic input is not at the high power level, but for generating the output with a low power level when either or both of the first and second logic inputs are at the high power level,
• whereby the high power level is restored.