Distribution of optical power in an optical transport system

An optical-power-distribution (OPD) subsystem for an optical transport system, said OPD subsystem comprising:

• an optical-power combiner having a plurality of input ports and an output port;
• and
• a first optical-power router having an input port and a plurality of output ports, wherein:
• the OPD subsystem is configured to be disposed between a plurality of lasers of the optical transport system and a plurality of line cards of the optical transport system to route optical signals generated by the lasers to the line cards to provide to each of the line cards of the plurality of line cards an optical-reference signal for coherent detection of a modulated optical input signal received by the optical line card;
• and
• the plurality of input ports of the optical-power combiner are configured to be coupled to the plurality of lasers so that each input port is either idle or configured to receive an optical signal generated by one of the lasers;
• the optical-power combiner is configured to combine the optical signals applied to the input ports thereof to produce a combined optical signal at the output port thereof;
• the input port of the first optical-power router is coupled to the output port of the optical-power combiner to receive an optical signal corresponding to the combined optical signal;
• and
• the first optical-power router is configured to split the received optical signal to produce a plurality of optical output signals at the output ports thereof and apply said optical output signals to a corresponding subset of the line cards.

A system, comprising:

• a plurality of optical line cards;
• a plurality of lasers that are external to the optical line cards;
• and
• an optical-power-distribution (OPD) subsystem disposed between the plurality of lasers and the plurality of line cards to route optical signals generated by the lasers to the line cards, wherein each of the optical line cards is configured to use a respective optical signal received from the OPD subsystem to provide one or both of:
• an optical-reference signal for coherent detection of a modulated optical signal received by the optical line card;
• and
• an optical-carrier signal to be modulated in the line card to generate a modulated optical output signal;
• and
• wherein the OPD subsystem comprises:
• an optical-power combiner having a plurality of input ports and an output port;
• and
• a first optical-power router having an input port and a plurality of output ports, wherein:
• the plurality of input ports of the optical-power combiner are coupled to the plurality of lasers so that each input port is either idle or configured to receive an optical signal generated by one of the lasers;
• the optical-power combiner is configured to combine the optical signals applied to the input ports thereof to produce a combined optical signal at the output port thereof;
• the input port of the first optical-power router is coupled to the output port of the optical-power combiner to receive an optical signal corresponding to the combined optical signal;
• and
• the first optical-power router is configured to split the received optical signal to produce a plurality of optical output signals at the output ports thereof and apply said optical output signals to a corresponding subset of the optical line cards;
• and
• wherein the OPD subsystem further comprises:
• a first optical-signal splitter having an input port and first and second output ports;
• and
• a second optical-power router, wherein:
• the input port of the first optical-signal splitter is coupled to the output port of the optical-power combiner;
• the first output port of the first optical-signal splitter is coupled to the input port of the first optical-power router;
• the second output port of the first optical-signal splitter is coupled to an input port of the second optical-power router;
• and
• the second optical-power router is configured to split the received optical signal to produce a plurality of optical output signals at output ports thereof and apply said optical output signals to a second subset of the optical line cards.