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

Step 1

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

Optical Grating - Inverse Problem Solver dialog box

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

Optical Grating - User Defined Function

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

Optical Grating - User Defined Function

9 Click OK.

Step 2

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

Optical Grating - Axis Properties

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

Optical Grating - Wavelength graph