Systems and methods for coherent optics in an access network

1. An interface subsystem for an access network, comprising:

a coherent optical transceiver comprising (i) a transmitting portion, (ii) a receiving portion, and (iii) a switching mechanism configured to switch operation of the coherent optical transceiver between a first operational mode compliant with a first physical layer specification and a second operational mode compliant with a second physical layer specification different from the first physical layer specification;

a control layer;

a pre-interface portion comprising a framing unit, wherein the framing unit includes (i) a forward error correction (FEC) coding unit, (ii) an Ethernet mapping unit, and (iii) an optical transport network (OTN) framing module;

an electrical interface portion in operable communication with the framing unit, and configured to transmit and receive first and second separate input 100 GbE electrical signals on a host side of the interface subsystem, wherein each of the first and second input electrical signals is according to the first operational mode;

an optical interface portion in operable communication with the coherent optical transceiver, and configured (i) for 200G optical transport, (ii) to, on a line side of the interface subsystem, transmit and receive optical signals to and from, respectively, an optical transport medium coupled to the line side of the interface subsystem, wherein the transmitted and received optical signals are according to the second operational mode;

a management interface portion in operable communication with the control layer; and

a directional element disposed at the line side between the optical interface portion and the coherent optical transceiver,

wherein the directional element is configured to route optical signals from the transmitting portion to the optical transport medium, and optical signals from the optical transport medium to the receiving portion,

wherein the optical interface portion comprises a dual interface architecture between the directional element and the coherent optical transceiver,

wherein the transmitting portion and the receiving portion are coupled with the optical transport medium through separate respective portions of the dual interface architecture,

wherein the electrical interface portion includes a mapping unit configured to individually process the first and second separate input 100 GbE electrical signals into a dual 100G frame structure, and a multiplexing unit configured to interleave the dual 100G frame structure into a single-output 200G frame structure, and

wherein the pre-interface portion is configured to integrate open FEC (oFEC) onto the single-output 200G frame structure in a continuous operation.

2. The interface subsystem of claim 1 , wherein the first operational mode is a 100G mode and the second operational mode is a 200G mode.

3. The interface subsystem of claim 2 , wherein the particular mode is the 100G mode, and wherein the electrical signals on the host side include a 100 Gigabit Ethernet (GbE) host.

4. The interface subsystem of claim 1 , wherein the transmitting portion comprises at least one of a symbol mapping unit, a linear and nonlinear pre-emphasis unit, a digital-to-analog converter, and an I/Q modulation and polarization combining unit.

5. The interface subsystem of claim 4 , wherein the receiving portion comprises at least one of an I/Q detection unit, an analog-to-digital converter (ADC), a deskew and orthogonality compensation unit, a chromatic dispersion compensation unit, a polarization mode dispersion compensation unit, a polarization multiplexing unit, a clock recovery unit, a carrier frequency offset compensation unit, a carrier phase compensation unit, a symbol demapping unit, an FEC decoding unit, an Ethernet demapping unit, and an OTN framing module.

6. The interface subsystem of claim 4 , wherein the receiving portion further comprises a feedback loop to the ADC from at least one of the deskew and orthogonality compensation unit, the chromatic dispersion compensation unit, the polarization mode dispersion compensation unit, the polarization multiplexing unit, and the clock recovery unit.

7. The interface subsystem of claim 4 , wherein the directional element is further configured to couple the optical transport medium with the I/Q modulation and polarization combining unit of the transmitting portion.

8. The interface subsystem of claim 7 , wherein the directional element is further configured to couple the optical transport medium with the I/Q detection unit of the receiving portion.

9. The interface subsystem of claim 2 , wherein the directional element comprises a single interface structure between the optical transport medium and the dual interface architecture.

10. The interface subsystem of claim 1 , wherein the coherent optical transceiver further comprises a symbol mapper configured to map frames of the 200G frame structure into optical polarization constellation symbols for transport over the optical transport medium.

11. An interface subsystem for an access network, comprising:

a coherent optical transceiver comprising (i) a transmitting portion, (ii) a receiving portion, and (iii) a switching mechanism configured to switch operation of the coherent optical transceiver between a 100G operational mode compliant with a first physical layer specification and a 200G operational mode compliant with a second physical layer specification different from the first physical layer specification;

a control layer;

a pre-interface portion comprising a forward error correction (FEC) encoder and a framing unit including a physical coding sublayer (PCS) and an optical transport network (OTN) module;

an electrical interface portion in operable communication with the framing unit, and configured to transmit and receive first and second separate input 100 GbE electrical signals on a host side of the interface subsystem;

an optical interface portion in operable communication with the coherent optical transceiver, and configured (i) for 200G optical transport, (ii) to, on a line side of the interface subsystem, transmit and receive optical signals to and from, respectively, an optical transport medium coupled to the line side of the interface subsystem, wherein the transmitted and received optical signals are according to the 200G operational mode; and

a management interface portion in operable communication with the control layer,

wherein the control layer is configured for operable communication with the framing unit and the coherent optical transceiver,

wherein the PCS is configured to encode and convey the electrical signals received at the host side to the transmitting portion of the coherent optical transceiver,

wherein the electrical interface portion includes a mapping unit configured to individually process the first and second separate input 100 GbE electrical signals into a dual 100G frame structure, and a multiplexing unit configured to interleave the dual 100G frame structure into a single-output 200G frame structure, and

wherein the pre-interface portion is configured to integrate open FEC (oFEC) onto the single-output 200G frame structure in a continuous operation.

12. The interface subsystem of claim 11 , wherein the transmitting portion comprises at least one of frame generator, a first bit interleaver, and a first bit de-interleaver.

13. The interface subsystem of claim 12 , wherein the FEC encoder is configured to implement differential coding onto the optical signals in the continuous operation.

14. The interface subsystem of claim 12 , wherein the FEC encoder is configured to code successive blocks of the optical signals into a codeword matrix in the continuous operation.