Frequency division multiple access optical subcarriers
A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.
1. A transmitter, comprising:
a laser operable to output an optical signal;
a digital signal processor circuit operable to receive first data and receive second data after receiving the first data, the digital signal processor supplying a first plurality of electrical signals based on the first data and supplying a second plurality of electrical signals based on the second data;
a plurality of digital-to-analog conversion circuits operable to provide a first plurality of analog signals based on the first plurality of electrical signals and a second plurality of analog signals based on the second plurality of electrical signals; and
a modulator operable to modulate the optical signal to provide a first plurality of optical subcarriers based on the first plurality of electrical signals and a second plurality of optical subcarriers based on the second plurality of electrical signals, each of the first plurality of subcarriers and each of the second plurality of optical subcarriers including an in-phase component and a quadrature component, such that a number of the first plurality of optical subcarriers is different than a number of the second plurality of optical subcarriers; and
a plurality of switches coupled to the digital signal processor, each of the plurality of switches selectively supplying an input to the digital signal processor,
wherein one of the plurality of switches is configured to supply control data to the digital signal processor, such that one of the plurality of optical subcarriers carries information indicative of the control data.
2. The transmitter in accordance with claim 1 , wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers is a Nyquist subcarrier.
3. The transmitter in accordance with claim 1 , wherein the digital signal processor includes a programmable gate array (PGA) is a digital signal processor.
4. The transmitter in accordance with claim 1 , wherein the digital signal processor includes a field programmable gate array (FPGA).
5. A receiver, comprising:
an optical hybrid circuit that receives local oscillator light, a first polarization component of a plurality of optical subcarriers and a second polarization component of the plurality of optical subcarriers, wherein each of the plurality of optical subcarriers is generated by modulation of an optical signal output from a laser, the optical hybrid circuit supplying a plurality of mixing products;
a photodiode circuit that provide first electrical signals based on the plurality of mixing products;
a digital signal processor that outputs data associated with the plurality optical subcarriers based on the first electrical signals, the processor circuit having a plurality of outputs; and
a plurality of switch circuits coupled to the plurality of outputs, the plurality of switch circuits selectively supplying portions of the data,
wherein one of the plurality of switch circuits supplies control data indicative of information carried by one of the plurality of subcarriers.
6. The receiver in accordance with claim 5 , wherein said each of the plurality of subcarriers is a Nyquist subcarrier.
7. The receiver in accordance with claim 5 , wherein the digital signal processor includes a programmable gate array (PGA).
8. The receiver in accordance with claim 5 , wherein the digital signal processor includes a field programmable gate array (FPGA).
9. A method, comprising:
generating an optical signal;
receiving first data with a digital signal processor and receiving second data with the digital signal processor after receiving the first data;
supplying, with the digital signal processor, a first plurality of digital signals based on the first data and supplying, with the digital signal processor, a second plurality of digital signals based on the second data;
supplying a first plurality of analog signals based on the first plurality of electrical signals and supplying a second plurality of analog signals based on the second plurality of electrical signals;
modulating the optical signal to provide a first plurality of optical subcarriers based on the first plurality of electrical signals and a second plurality of optical subcarriers based on the second plurality of electrical signals, each of the first plurality of subcarriers and each of the second plurality of optical subcarriers including an in-phase component and a quadrature component, such that a number of the first plurality of optical subcarriers is different than a number of the second plurality of optical subcarriers; and
supplying control data to the digital signal processor, such that one of the first plurality of optical subcarriers carries information indicative of the control data.
10. The method in accordance with claim 9 , wherein each of the first plurality of optical subcarriers and each of the second plurality of optical subcarriers is a Nyquist subcarrier.
11. The method in accordance with claim 9 , further including selectively supplying an input to the digital signal processor.
12. The method in accordance with claim 9 , wherein the digital signal processor includes a programmable gate array (PGA) is a digital signal processor.
13. The method in accordance with claim 9 , wherein the digital signal processor includes a field programmable gate array (FPGA).