Dear Lared dar,
You may use the tool box in the OSA visualizer. You need to right click in the display window then get access to the marker and info tools. Another option is to use the WDM Analyzer to get details on each existing wavelength/frequency in your project, then calculate the ratios. You may add your own VB scrip in the component to calculate the ratio. You could access the VB scripting window of the analyzer by right click on it then choose Component script.
Regards,
Ahmad