Guided Wave Optical Components and Devices

CHAPTER 15

Optical Fiber Gratings

K. Thyagarajan^*,     Physics Department, Indian Institute of Technology Delhi, New Delhi, India

1 INTRODUCTION

Optical fiber gratings consist of a periodic modulation of refractive index along the core of an optical fiber. There are two main types of fiber gratings, namely short period gratings and long period gratings. Short period gratings, also referred to as fiber Bragg gratings (FBG), have periods on the order of half a micrometer for operation around the 1550-nm window, whereas long period gratings (LPG) have periods of a few hundred micrometers. Both types of gratings exhibit strong wavelength dependent characteristics and hence have important applications in wavelength division multiplexed (WDM) optical ...