This all-optical switch provides flip-flop latching above 10 GHz and is controlled by optical signals which can be remote from the bi-stable device, a semiconductor optical amplifier
In optical communication networks, this all-optical latching switch can be used for such network processes as bit-length conversion, data format change, de-multiplexing, packet header buffering and re-timing in wavelength division multiplexed (WMD) systems.
Optical flip-flops are applicable to any signal processing function that requires memory, particularly those that require sequential logic. Examples of such uses are: data-format conversion, 3R regeneration, temporal de-multiplexing, switching and routing, buffering, clocks, oscillators, clock dividers, latches, registers, counters, adders and transistors. The technology can be applied in Photonic Integrated Circuits (PICs) and in planar lightwave circuits (PLCs) for those signal processing functions that require memory. PICs are used for optical signal transmitters and receivers. The technology also allows a single pair of control signals to act on many flip-flops arranged in parallel, which would provide flexibility and reduce power consumption in fan-out and photonic integrated circuits.
This concept could enable all-optical communication and data processing at speeds up to 100 GHz. Because such optical switching is not yet possible, networks today convert optical signals to the electronic domain for any sequential data processing requiring memory, with electrical flip-flop circuits typically limited to1 GHz. All-optical circuits will be faster, more compact, less expensive and free from EMI/EMP interference. The control technique is expected to work over a wide range of wavelengths with pulse width as small as 1 picosecond. The concept splits the function of the control block, which is remote from the latching switch itself, which can be any optical flip-flop enabled by a holding beam, including devices based on dispersive bistability, absorptive bistability and other nonlinear effects. The control signals are communicated on the same fiber as the holding beam, and do not require a separate fiber. Many devices could be controlled by single control block. The system does not require a clock, (asynchronous operation) because the set and reset pulses are both derived from the same pulse. The concept has been demonstrated with sub-mililiwatt control pulses at 1539 nm, with a pulse width of 5 ns, yielding an on-off contrast of greater than 3 dB.