Today’s systems and networks rely on new technologies like reconfigurable add-drop multiplexers (ROADM), and transmit at speeds reaching 40G and 100G. In such a challenging technological environment, getting reliable in-band OSNR values is key—which is exactly what the IQS-5240S/BP provides, thanks to EXFO’s polarization-resolved optical spectrum (PROS) OSNR measurement approach.
The IEC subsystem test procedure 61280-2-9 defines OSNR measurement as the power ratio between the peak power and the noise at half the distance between the peaks. Using this method, as shown in figure 1, the noise level at the channel (or peak power) wavelength (Ni) is interpolated from the noise level between the channels (N(λi + Δλ) and N(λi - Δλ)). Figure 2 shows the OSA trace of a DWDM network where the interpolation method can properly troubleshoot the optical layer. However, in ROADM or 40 Gbit/s systems, this method may lead to incorrect results since the noise level between the peaks is no longer directly correlated with the noise level at the channel wavelength. For instance, Figure 3 displays closely spaced 40G signals that require in-band OSNR measurement, since the power level between channels is higher than the actual noise due to channel overlap.
The built-in polarization-resolved optical spectrum method of EXFO’s IQS-5240S-P and IQS-5240BP OSAs enables you to achieve accurate in-band OSNR measurements of a ROADM or 40 Gbit/s system directly and automatically.*
Key Features
- Breakthrough approach: in-band OSNR measurement for 40 Gbit/s systems and ROADMs
- Flexibility to analyze WDMs, EDFAs, drift, spectral transmittance and DFB lasers
- Fast, accurate scans—no compromise on dynamic range or resolution bandwidth
- GPIB or LAN remote control using SCPI commands and LabVIEW drivers
- One-button operation for easy setup and automatic measurement