JDSU offers true OSNR measurement for ROADM networks

Dec. 12, 2007
DECEMBER 12, 2007 -- JDSU has announced improved measurement analysis for its in-band optical spectrum analyzer (OSA) for the T-BERD/MTS-8000.

DECEMBER 12, 2007 -- JDSU (search for JDSU) has announced improved measurement analysis for its in-band optical spectrum analyzer (OSA) for the T-BERD/MTS-8000. The OSA-320 module, a high-performance OSA, incorporates what JDSU describes as "a unique and highly accurate" method for measuring the "true" optical signal-to-noise ratio (OSNR) in reconfigurable optical add/drop multiplexer (ROADM) networks.

The JDSU OSA-320 module was engineered to test optical performance in the agile optical network (AON), a dynamically reconfigurable DWDM network that is designed to accelerate triple-play service deployment, simplify network management, and enable advanced wavelength applications at significantly reduced costs. In the AON, multiple ROADMs with different "filtering" technologies can be cascaded in a link, creating OSNR measurement problems for conventional OSA devices that employ out-of-band methods, according to JDSU. Even the most recent OSA devices using the "shoulder method" may not provide accurate OSNR results for different ROADM filter shapes at high data rates, the company adds. The new measurement analysis method is designed to overcome such issues and enable accurate measurement of the true OSNR in all deployment scenarios of ROADM networks (from 10G to 40G), regardless of the filter type integrated into the ROADM.

In ROADM networks, each channel may traverse different routes, optical amplifiers, and add/drop filters, resulting in different OSNR for each channel. JDSU says that conventional OSA measurements are therefore unreliable, as they indicate OSNR values that are too high -- up to 10 dB above the true OSNR, in the company's estimate. The OSA-320 follows an optical polarization splitting (OPS) method for measuring OSNR inside the optical channel (in-band OSNR) to provide a more a accurate OSNR measurement.

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