MAY 10, 2010 By Stephen Hardy -- The Optical Internetworking Forum (OIF) has approved one of the key implementation agreements (IAs) within its 100G DWDM project. The 100G Integrated Polarization Intradyne Coherent Receiver IA describes several aspects of integrated receivers that can be used for DWDM applications at 100 Gbps and potentially higher data rates.
As with all the IAs within the OIF’s 100G project, the receiver described in the new agreement supports dual-polarization quadrature phase-shift keying (DP-QPSK) modulation as specified in the OIF’s 100G Framework Document. It specifies operating rates up to 32 GBd. However, the OIF says the IA has been designed to be agnostic to format and data rate to increase the chances it can be used at even higher data rates enabled via other modulation formats.
The IA defines the follow attributes:
- Required functionality
- High-speed electrical interfaces
- Low-speed electrical interfaces
- Mechanical requirements
- Environmental requirements.
- Specifications for opto-electronic interfaces.
The agreement does not define the type of technology used in the receiver’s photonics subcomponents or the expected optical transmission performance of systems using receivers that conform to the IA. It also is designed to enable product and performance differentiation among technology suppliers.
The coherent receiver described in the IA comprises:
- Eight photodetectors, comprised of four sets of balanced detectors
- Four linear amplifiers with differential output
- Two 90-degree hybrid mixers with differential outputs
- A polarization splitting element, separating the input signal into two orthogonal polarizations, with each polarization delivered to a hybrid mixer
- A polarization-maintaining power splitter or polarization splitting element, which splits the local oscillator power equally to the two hybrid mixers.
The IA states that, at a minimum, the first three of these functions must be contained in single component.
Additional required functionality spelled out in the IA includes:
- Automatic gain control (AGC) and/or manual gain control (MGC)
- User-settable output voltage swing
- Independent output swing adjustment for each of the four outputs
- Peak indicators for each output.
The OIF released the companion transmitter IA this past March (see “The OIF approves 100G transmitter implementation agreement”).
Meanwhile, the OIF also announced completion of a forward error correction (FEC) whitepaper that summarizes the organization’s investigation of FEC for use with 100G DP-QPSK transmission in long distance DWDM communications.
Both the new IA and the FEC white paper are available on the OIF website.