Abstract: A data communication system for transmitting packets over one or more optical fibers includes a transponder with a number of digital signal processors that transmit data packets on different optical channels. The transponder includes a switch that receives a data packet on an input and selects one of the digital signal processors to transmit the packet based on quality metrics for the different optical channels and/or information included in an OSI header for the data packet.

Abstract: A data communication system for transmitting packets over one or more optical fibers includes a transponder with a number of digital signal processors that transmit data packets on different optical channels. The transponder includes a switch that receives a data packet on an input and selects one of the digital signal processors to transmit the packet based on quality metrics for the different optical channels and/or information included in an OSI header for the data packet.

Abstract: A non-linear crystal is used as an optical radiation frequency converter. Its efficiency is optimized though control of one or more operating conditions that include the temperature of the crystal, its angular relationship with incident radiation and an electric field bias in which the crystal operates. The relative phase between radiation incident upon the crystal and that generated by it is adjusted by a servo loop which controls one or more of these operating conditions. The servo loop responds to a cyclic variation in the output radiation which occurs when the crystal is not operating at an optimal efficiency. A quasi-phase matched (QPM) crystal is preferred. Several specific crystal structures are described. The technique has an application in a frequency doubler, among others.