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# Lesson 17: Modal Analysis of an Anisotropic Buried Waveguide

## Introduction

This lesson simulates the effect of anisotropy by considering a buried guide. The core has an anisotropy relative permittivity tensor with components εxx   = εzz   = 2.31 and εyy   =  2.19 . It is buried in a cladding and substrate of permittivity ε2 =  2.05 . Figure 1: Cross section of anisotropic buried rectangular optical waveguide The procedures are:…

## Defining Materials

To define the materials for the Anisotropic 3D Mode solver, perform the following procedure. Step Action 1 In the Layout Designer, from the File menu, select New. The Initial Properties dialog box appears. 2 Click Profiles And Materials. The Profile Designer opens. 3 Under OptiBPM Designer 1, in the Materials folder, right-click the Dielectri folder and…

## Creating the Profile

To create the rectangular buried waveguide profile, perform the following procedure. Step Action 1 Under OptiBPM Designer 1, Profiles folder, right-click on Channel, and select New (see Figure 4). 2 Type the following Profile name: BuriedAniso 3 Type/select the following values: a.   2D profile definition Material: AnisoEps b.   3D profile definition Layer name: Layer0 Width:…

## Defining Layout Settings

To define the layout settings, perform the following procedure. Step Action 1 In the Initial Properties dialog box, type/select the following (see Figure 7): a.   Default Waveguide tab Profile: BuriedAniso b.   Wafer Dimensions tab Length (μm): 200 Width (μm): 6 c.   3D Wafer Properties tab Cladding Material: Eps Thickness: 3 Substrate Material: Eps Thickness: 2…

## Creating the Linear Waveguide

To create the linear waveguide, perform the following procedure. Step Action 1 In the layout, draw a linear waveguide. 2 To open the properties dialog box for the waveguide, double-click on the waveguide. The Linear Waveguide Properties dialog box appears. 3 In the Linear Waveguide Properties dialog box, type/enter the following (see Figure 7): a.   Start…

## Setting Simulation Parameters

To set the simulation parameters perform the following procedure. Step Action 1 In the Layout Designer, select Simulation > Simulation Parameters. The Simulation Parameters dialog box appears. 2 Click the Global Data tab. 3 Type 1.0 in Wavelength. 4 Click the 3D Anisotropic tab (see Figure 9). 5 In BPM solver, select Pade(1,1). 6 In…

## Viewing the Refractive Index Distribution (X-Y cut)

To view the permittivity distribution, perform the following procedure. Step Action 1 In the Layout Designer, click the Permittivity XX – 3D XY Plane View tab (see Figure 10). 2 Select Preferences > Refractive Index View > 3D Slice XY Plane. The label of the tab changes to Permittivity XX – 3D XY Plane View. 3…

## Calculating the Mode

To calculate the mode, perform the following procedure. Step Action 1 In the layout, double-click the input plane. The Input Plane dialog box appears (see Figure 11). 2 Click the Input Fields 3D tab. Figure 11: Input Field dialog box 3 Click Edit. The Input Field dialog box appears.4Click the All button.5Select the item in…

## Computing the Magnetic Field

Step Action 1 Open the Global Data: ADI Method dialog box and select the Advanced tab (see Figure 18). Figure 18: Advanced settings for the Anisotropic 3D Mode solver 2 In the Engine window, select H Formulation (Magnetic). 3 To start calculating the modes, click Run. The OptiBPM_M3Dsim window appears. In addition to the mode Hx11…

## References

[1]           M. Ohtaka, “Analysis of the guided modes in the anisotropic dielectric rectangular waveguides”, Trans. Inst. Electron. Commun. Eng. Japan, Vol J64-C, pp. 674-681, Oct 1981. [2]           Yilong Lu and F. Anibal Fernandez, “An Efficient Finite Element Solution of Inhomogeneous Anisotropic and Lossy Dielectric Waveguides”, IEEE Trans. Microwave Theory Tech., vol. MTT- 41, pp. 1215-1223, June/July. 1993.