Fault-tolerant system using all-optical sensing and feedback circuits

Abstract

ABSTRACT This study suggests an optical fault-tolerant system using all-optical sensing and feed back circuits with photorefractive crystals. The first example is a fault-tolerant system in which the system independently detects a cutoff of the optical transmission line and converts its routing to the backup line. Next, while practical application of holographic optical memory is currently being developed, under proposing system, the memory system automatically detects the loss of information (dropout) in optical memory, and reloads and eventually restores the corresponding data from the backup memory. Keywords: Fault-tolerant system, Optical router, Optical memory, All optical system 1. INTRODUCTION With the development of computing systems and networking technology, we currently see more complicated large-scale systems for information communication. Thus, a fault-tolerant quality is in great demand in system architecture. The same is true with the increasingly important area of optical devices and optical network systems. To help realize the fail-safe function in optical systems, studies have been performed mainly regarding methods of duplicating and electronically converting the system. However, installing an electronic device in all optical devices including optical memory or optical fiber to preserve the fault-tolerant quality may result in a very complicated system. Not only that, it can lead to restricting the performance of optical devices as well as restricting the convenience and application range of the optical network system. Therefore, one goal of this study is to maintain the fault-tolerance in optical communication lines and optical memory devices --- including the phase of detecting faults and releasing operations --- based on autonomous control by light without using any additional electronic control systems. The other goal is to suggest a new optical feedback system and to conduct a basic investigation of it.