Impact of Advanced Optical Communication Technology on Lightwave Sensing


IEICE TRANSACTIONS on Communications   Vol.E75-B    No.4    pp.256-266
Publication Date: 1992/04/25
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section INVITED PAPER (Special Issue on Advanced Optical Communication Technologies for New Applications)
lightwave sensing,  fiber optic sensor,  distributed sensor,  coherence,  fiber gyroscope,  

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According to the development of optical communication technologies, it is getting easier to handle new devices, such as optical fibers, semiconductor light sources, guided wave devices, and optical integrated circuits. These devices have recently given considerable impact on the optical sensing field. The optical sensing shares the optical devices and the concepts of signal processing or system configuration with the optical communication. In this paper, the advanced lightwave sensing technology is discussed, considering the relation to the advanced optical communication technology. Distributed fiber sensors and the application of coherence characteristics of semiconductor light sources are the topics to be mainly discussed. In the distributed fiber sensors, the fiber plays both a role of low-loss transmission line and a role of lengthwise deployed sensing element. According to the change of characteristics of light propagating in the fiber, distribution of various physical parameters can be measured, such as the fiber loss, temperature, and strain. Optical Time Domain Reflectometry is employed to determine the location. Another tendency in the lightwave sensing field is the use of coherence characteristics of various semiconductor light sources. Low coherent source provide a highly sensitive inertial rotation sensor, that is, interferometric fiber optic gyroscope. Another type of optical gyroscope, optical passive ring-resonator gyro, has been studied as an application of a high coherence source. Frequency tunability of the semiconductor laser, especially that of tunable DFB or DBR lasers, can provide new ways in signal processing in the sensors. Optical coherence function can be synthesized also by utilizing the tunability. In conjunction with the progress in optical communication, lightwave sensing fields are steadily increasing.