Guided Wave Optics and Photonic Devices

1	Concept of Modes in Optical Waveguides Ajoy Ghatak and K. Thyagarajan Indian Institute of Technology Delhi

CONTENTS

1.1    Introduction

1.2    Te Modes

1.3    Tm Modes

1.4    Physical Understanding of Modes

Reference

1.1    INTRODUCTION

In the design of an optical communication system, it is necessary to understand the concept of modes, which will be explained in this chapter. And to understand the concept of modes, it is probably best to consider the simplest planar optical waveguide, which consists of a thin dielectric film sandwiched between materials of slightly lower refractive indices and is characterized by the following refractive-index variation (see Figure 1.1):

$n(x)=\{\begin{array}{l}{n}_1;\left|x\right|<\frac{d}{2}\\ n_2;\left|x\right|>\frac{d}{2}\end{array}$

(1.1)

with n₁ > n₂. Equation 1.1 ...