This is a high speed, all-optical latching switch built from a DFB semiconductor laser used in a unique manner as an optical amplifier.
The latching capability enables such optical communication network processes as bit-length conversion, data format change, de-multiplexing, packet header buffering and re-timing. The latching would typically be used to increase the bit length (increasing the energy in the pulse), while the device simultaneously performs a wavelength conversion to a pre-defined color. Optical communication networks have a need to convert the short pulses used on backbone and trunk lines at 10 Gb/sec or more to the longer pulses used on local networks.
Wavelength conversion is now done on WDM (wavelength division multiplexed) systems by converting the optical signal to electronics and then converting back to optical, using a photo detector, electronic memory and an output laser. The fastest of these electronic switches are limited to 0.6 Gb/s. MEMS, liquid crystal and bubble jet concepts are also being examined for latching switches, but these all have switch times in milliseconds. Switching in our new all-optical flip-flop occurs in about 500 pico-seconds and should operate faster than 10 Gb/s. The all-optical flip-flop latching switch using the new mechanism is expected to be compact, relatively inexpensive and easily integrated into a monolithic optical buffer. For example, an array of 32 devices could be used to store a packet for routing signals through a cross-connect optical circuit.
The device concept has been demonstrated using a commercially available DFB (Distributed Feedback) semiconductor optical laser driven as a semiconductor optical amplifier (SOA) while using a polarization-maintaining 50/50 fiber coupler to connect to the holding laser which defines the output signal wavelength. The concept has been extended in later work in UR 3-11155-08002, "Optical Flip-Flop Latching Switch with Remote Optical Control".