There has been a renewal of interest in optical networking companies recently with the anticipated shift to 100G technologies poised to happen soon. Various players are positioning themselves for this big industry shift. Along with this interest in all things 100G, there is also an industry evolution from the early generations of ROADM technology (Reconfigurable Optical Add Drop Multiplexer) to newer versions that provide a significantly higher degree of flexibility and reconfigurability.

Reconfigurable Optical Add/Drop Multiplexers (ROADMs) technically refer to a network element that has the capability of adding/dropping selected wavelengths for local traffic as well as redirecting express traffic to other directions in a multi-degree node. The “Reconfigurable” part in ROADM refers to the ability to do this local add/drop as well as the redirection of express wavelengths in a dynamic fashion from a remote network operations center and without manual re-fibers of line cards and with minimal pre-planning to account for uncertain traffic patterns. This reconfigurability is the key to efficient network adaptation to unforeseen demand patterns and customer connects/disconnects without costly service disruptions. The term ROADM, has been used more broadly than just the network element itself and has been used to refer to (a) an optical transport system that incorporates ROADM technology, and (b) optical components and sub-systems (made by companies such as JDSU) that form the building blocks of the ROADM system.

100G networking and associated optical products can be broadly classified into (a) client side, short-reach, standardized, pluggable optical modules that are used to connect short reaches between routers/switches and transport equipment or among switches, and (b) line side models, DWDM interfaces that are proprietary, vendor specific and cover distances of 1,000 - 2,000 km.

Early low-volume shipments of client side interfaces, which are standardized by IEEE, have commenced and the key players for these interfaces are Finisar, Santur and Opnext. The client side models have not yet reached attractive price points compared to 10G modules, hence slow uptake of the models is projected until the cost-volume positive feedback cycle kicks into higher gear. While early parts are sampling this year, rapid market adoption is highly predicated on the cost points of the modules.

On the DWDM line side that covers geographical reaches across regional, long-haul or ultra-long haul distances, there has been a concerted effort by all major optical equipment vendors to introduce 100G capable systems. The advantages of 100G on the line side are very compelling, as it increases the fiber capacity to 8 Tb/s and the preferred technology path using coherent optical transmission provides a number of additional advantages of simpler link design and inherent compensation of some fiber impairments such as chromatic and polarization mode dispersion. The advantages of 100G systems and reasonable price points relative to 10G systems will facilitate line adoption of 100G; it is expected to occur rapidly once systems are available in early to mid 2011. While early versions of 100G line side technology are available now, optimized and field deployable systems are expected in 2011. The major players in this space are Ciena/Nortel, Alcatel-Lucent, Nokia-Siemens, Huawei and Infinera. Each of the vendors has announced slightly varying flavors of the technology and approaches. With the R&D focus on 100G and coherent technology and the commoditization of 10G technology, it appears that 40G technology is being squeezed out in carrier applications (for both line side and client side applications). This was reinforced by Infinera’s recently announced decision to discontinue 40G non-coherent PIC (Photonic Integrated Circuit) and focus resources on 100G coherent technology in a PIC.

Along with the evolution from 10G to 100G discussed above, the other major area of interest in the optical networking space is the emergence and adoption of next-generation ROADMs that provide colorless, directionless and contentionless capabilities. The first generation of ROADMs introduced in 2003-2004 enabled the carriers to add/drop some wavelengths without disrupting other wavelengths. While this provided a huge improvement over the previous method of operation, it still had a number of limitations in terms of a fully automated reconfigurability. Newer optical building blocks and lower costs are enabling the realization of next-generation ROADM architectures which remove these limitations. Directionless ROADMs enable a common bank of transponders to connect to any direction in a multi-degree node. Colorless ROADMs enable a transponder to flexibly connect to any mux/demux port and contentionless ROADMs enable use of the same wavelength in different segments of a network with a common node. The key building blocks for these new levels of reconfigurability is higher port count WSS (Wavelength Selective Switches) and smaller, lower cost WSS switches. These advances are expected to catalyze the ROADM market and continue the high growth trajectory of this sub-segment of the optical component space and continue to benefit ROADM market leaders like JDSU.

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