In order to simulate weight measurements with OptiGrating, you would need to evaluate the strain in the fiber due to the weight separately. Typically, a calibration table of weight versus stress/strain is available from vendors of FBG sensors.
Once you have evaluated the strain in the fiber due to the weight, you can input the strain and the strain-optic parameters of the fiber in the Grating Sensor dialog box to simulate the effect on the grating. OptiGrating can be used to synthesize and analyze the shift in the central wavelength of the grating when a weight is placed on the fiber.
To access the Grating Sensor dialog box, open the Parameters menu and click “Grating”. In the Grating Manager dialog box, double click the desired grating to open the Grating Definition dialog box. Finally, enable the “Sensors” checkbox, and click “Define” to open the Grating Sensor dialog box. Once you have accessed this dialog box, you can enter the values for strain and the strain-optic parameters.