In this lesson we show an example of the synthesis of a filter with an arbitrary user
defined spectrum. In this example, we ask for a bandpass filter having a reflection
coefficient with a linear variation of amplitude (the reflectivity has a square root
variation).

Step 1

1Choose File > New > Single Fiber.
2Then select Calculation > Inverse Scattering Solver, to get Inverse Problem Solver dialog box.
3In the Inverse Problem Solver box, make sure the User-Defined checkbox is checked.
4Enter the starting and ending wavelengths, and the number of Steps in the User-Defined frame as shown.

Optical Grating - Inverse Problem Solver dialog box

5Click on the Define button next to the Ref/Tran and enter the formula shown below to define the reflectivity.

Optical Grating - User Defined Function

6Click OK.
7Select the Disp button.
8Click on the adjacent Define button to define the dispersion.

Optical Grating - User Defined Function

9Click OK.

Step 2

1Click on Start to reconstruct the grating.
2Select the Power tab at the bottom of the screen to see the reflected and transmitted power.
3Right click the mouse in the graph window to pull down the menu and select Axis Properties.

Optical Grating - Axis Properties

4Select the Left Y axis and uncheck the Show in dB box to show the reflection in a linear scale.
5Click OK.

Optical Grating - Wavelength graph