Hello Nail,
Unfortunately, we can’t support issues with OptiSystem 7.0. However, you should be able to view the signal structure of the data file and examples of FBG design done in OptiGrating and loaded into OptiSystem 16.1. These files are located at C:\Users\USER NAME\Documents\OptiSystem 16.1 Samples\Software interworking\OptiGrating.
Regards,
Ahmad