To calculate the mode, perform the following procedure.

Step Action
1 Put an Input Plane in the layout.
2 Double click on the Input Plane to get the Input Plane dialog box.
3 Select the Mode starting field.
4 Select the Input Fields 3D tab.
5 Click Edit.

The Edit Input Field dialog box appears.

6 Click All.

The information from the Waveguides list appears in the Fields list.

7 Click Mode.

The Calculate Mode dialog box appears.

8 Click Calculate Mode.

The Global Data:ADI Method dialog box appears (see Figure 9).

9 Type/select the following:Solver:  Real

Mode: Semi-vector TE

BPM - Figure 9 Global Data:ADI Method dialog box

Figure 9: Global Data:ADI Method dialog box

10 On the Settings tab, select Boundary Condition: Neumann.
11 Select Starting Field: Gaussian and click Properties.

The Gauss Field Parameters dialog box appears (see Figure 10).12In the Gauss Field Parameters dialog box, select Type: User defined.13Type the following:

Center X [ μm ]: 0

Center Y [ μm ]: -15

Halfwidth X [ μm ]: 3

Halfwidth Y [ μm ]: 3

BPM - Figure 10 Gauss Field Parameters dialog box

Figure 10: Gauss Field Parameters dialog box

14 Click OK.
15 Click Calc. Mode.

The OptiBPM_M3Dsim window appears (see Figure 11).

Note: The modal index for Mode 1 is: 1.45524303. You can also view the electric field distribution in the simulation window.

BPM - Figure 11 Calculated modal index and modal field of triangular core fiber

Figure 11: Calculated modal index and modal field of triangular core fiber

The table below compares the above results to the modal indices generated with the Finite Difference Method of OptiFiber.

Modal Index (ADI Method)                              1.45524303

Finite Difference (OptiFiber)                          1.4552448

The results agree well. The difference is in the order of 10-6.