Lesson 15: Step Index Fiber Modes

Introduction

Optical fiber is an important component of a device used for making fiber directional couplers and for launching and receiving light from an integrated optical waveguide In a device where a small length of fiber is used, the only characteristics needed to simulate for a fiber are the effective mode indices and mode field profiles. This…

Step Index Fiber – Fiber Parameters of SMF-28

This is the most widely used fiber for constructing optical devices. We will demonstrate the design for SMF-28, a commercially available fiber from Corning. We will also compare the results of 3D mode solver with Finite Difference method of OptiFiber from Optiwave Corporation. Fiber parameters of SMF-28 Core radius: 4.07μm Refractive index of core: 1.45205 Refractive…

Creating the SMF-28 Fiber Profile

To create the SMF-28 fiber profile, perform the following procedure. Step Action 1 In the Profile Designer, create the following Fiber Profile (see Figure 2): Profile name: SMF-28 2D profile definition tab Material: core 3D profile definition tab Layer name: core Rx: 4.07 Ry: 4.07 Material: core Figure 2: Defining the fiber profile

Defining Layout Settings

To define the layout settings, perform the following procedure. Step Action 1 In the Layout Designer, select Edit > Wafer Properties. 2 Type/select the following: Wafer Dimensions tab Length (μm): 1000 Width (μm): 60 2D Wafer Properties tab Cladding Material: cladding 3D Wafer Properties tab Cladding Material: cladding Thickness: 30 Substrate Material: cladding Thickness: 30…

Setting Simulation Parameters

To set the simulation parameters, perform the following procedure. Step Action 1 In the Simulation Parameters dialog box, click the 3D Isotropic tab. 2 Type/select the following: Number of points in mesh Number of points/ μ m X: 5 Y: 5 View cut X Mesh Pt: 151 Y Mesh Pt: 151 3 Click OK. Figure…

Viewing the Refractive Index Distribution (X-Y cut)

To view the refractive index distribution, perform the following procedure. Step Action 1 In the Layout Designer, click the Ref. Index (n) – 3D XY Plane View tab (see Figure 5). Note: To view the color palette, select View > 3D Graph Items > Palette. Figure 5: Refractive index distribution 2 Click the Plane View buttons…

Calculating the Mode

To calculate the mode, perform the following procedure. Step Action 1 In the Layout Designer, select Simulation > Simulation Parameters. The Simulations Parameters dialog box appears. 2 On the Global Data tab, type/select the following: Starting Field:  Modal Wavelength: 1.30 Reference Index: Modal 3 Open the Input Plane. 4 Select the Input Fields 3D tab.…

Comparing Results with Finite Difference Method of OptiFiber

Change the Polarization to SemiVector TE. In the Simulation Parameters dialog box, Global Data tab, edit the Wavelength from 1.30 to 1.65, and then re-calculate the modal indices. Compare the results to the modal indices generated with the Finite Difference Method of OptiFiber shown in Table 11. Table 11: Comparison of Modal Indices for SMF-28: OptiBPM vs…