Optical Switching

8Liquid Crystal Switches

Swarnil Roy^1,2 and Manash Chanda²

¹ IEEE SSCS Kolkata chapter, Kolkata, West Bengal, India

² Department of Electronics and Communication Engineering, Meghnad Saha Institute of Technology, Kolkata, West Bengal, India

8.1 Introduction

Bandwidth demand in modern communication systems calls for optical communication links and networks. Optical switches are an integral part of optical communication networks and optical sensing architecture because they can dynamically control the optical path connection. But if there is any optical to electrical conversion in the path that would crunch the bandwidth, all‐optical switches are preferred in that context. Also, optical switches with no moving parts ensure high stability and reliability.

But it is also important to identify specifically where to apply liquid crystal (LC) technologies, as they have limitations as regards response time, which is not less than several microseconds. The main focus of this chapter is the purpose of LC optical switches in space switching (telecom and sensor applications), in protection and recovery applications, and optical add/drop multiplexing, which need fewer restrictions about switching time.

Networks that can detect a failure and have an additional path in order to maintain the transmission when failure is detected are called protection and recovery networks. Optical add/drop multiplexer (OADM) is an optical multiplexer which insert or extract optical wavelengths to or from the ...