In an article a few weeks ago, we discussed the trend towards plug-in optics in consistent transmission systems and defined some basic concepts such as ACO (Coherent Analog Optics) and DCO (Digital Coherent Optics). In this article, I would like to shed some further details on the CFP2-ACO consistent optical transducers, which is generating considerable interest for the next generation of 100G metro systems. System designers want to switch to plug-in transceurs for consistent 100G applications to take advantage of the “Pay as you grow” advantage by adding only the expensive 100G optics when traffic is available to bear the extra costs. At the same time, designers are pushing for smaller transceurs to increase bandwidth density, making the small size of the CFP2 form factor attractive. These two wishes created a problem because the current technology could not adapt to all the elements necessary for a coherent 100G transceiver, either in physical size or in the electricity budget of a MFF2. The solution to the problem was to define a new type of coherent transceiver, CFP2-ACO, and to develop newer and smaller optical components. The consortium of on-board opticians (COBO) is expected to complete its module specification by the end of the year. For 7×5-inch and 4×5-inch MSA transponders, the management interface focuses on system level settings, while for CFP2-ACO, lower optical parameters are accessible due to analog transmission and module receiving signals. A specification design defining the mechanical aspects of on-board optics – dimensions, connectors and electrical interface – is already verified by the consortium members. PCP2-ACO is beginning to be introduced in a multitude of platforms. Arista Networks has added a CFP2-ACO line card to its 7,500 atms, while several optical transport providers use the module for their data center connection platforms. Several multi-source agreements (MSOs) have coherent optical modules. The most important trade show for the related optical module industry is the Optical Fiber Conference (OFC), held annually in Southern California.
Ecoc in Europe and FOE in Japan are other leading trade shows for the sector. Especially in the long-haul module market, the In Forward Error Correction (FEC) module has been included. It was both in proprietary form and in standard form. Consistent optical modules have sometimes used SOFT DECISION decoder algorithms FEC With this new approach, CFP2-ACO is a demanding component to design and build. The CFP2 form factor has nominal dimensions of 41.5 mm in width and 91.5 mm in length and 12.4 mm in height. The consistent optical components of the first generation were simply too large to fit the GFP2 packaging. For example, the first coherent receiver defined by the OIF, “Implementation Agreement for Integrated Dual Polarization Intradyne Coherent Receivers” OIF-DPC-RX-01.0 (known as Type 1), in 2010, certain dimensions, including 75 mmx41mm bridles and fiber boots. The recipient himself would absorb almost the entire envelope of the CFP2, an obvious non-departure.
Even the Type 2 RIC, defined by the OIF in 2013, was too large and had dimensions such as 45mmx22mm straps and boots. The OIF responded this year with a new MSA agreement for a micro-RIC specifically designed for a CFP2 ACO, “Implementation Agreement for Integrated Dual Polarization Micro-Intradyne Coherent Receivers,” OIF-DPC-MRX-01.0, with maximum dimension, including flanks, boots and 43mmx16mm flanks and pins.