PLZT-Based Shutters for Free-Space Optical Fiber Switching

Abstract

With the increasing demand for optical fiber switching technologies from data center networks, shutter-based free-space optical fiber switching technology is promising for such network applications as the major advantages of this switching technology are that multicast switching, which is a vital functionality required in data center networks, can be easily achieved through its optical fan-out mechanism and that the switching performance can also be significantly strengthened while new materials with a faster response time are used as a spatial light modulator (SLM) to act as shutters. In this paper, the characteristics of ferroelectric liquid crystals and lead lanthanum zirconate titanate EO ceramic (PLZT) materials used as an SLM to act as shutters based on a type of strips for free-space optical fiber switching technology have been investigated. Although the PLZT-based shutters have a fundamental characteristic that a higher driving voltage might be required in order to provide a fast switching time less than a subnanosecond, with the use of a simple push–pull amplifier circuit design that can make a small input signal ride on a large dc voltage, the driving of a PLZT device in an optical switch can easily be achieved. Although the power consumption problem of this PLZT device resulting from a high driving voltage was not investigated in this paper, it can be effectively improved through a general boost converter that can be used to raise a small input dc voltage to a required higher driving voltage for the PLZT device. A proof of concept $1\times N$ , i.e., a 1 $\times$ 6 free-space optical fiber ribbon switching architecture capable of scaling to an $N\times N$ switching architecture for data center network application, was experimentally implemented to investigate the fiber array switching properties of PLZT-based shutters based on a type of strip. The experimental results show that the bit error rates estimated from the $Q$ -factor were all less than $10^{-9}$ and that the jitters were all less than 7.35% under a variety of shutter driving voltages at a link speed of 1 Gb/s and above.