Application of guided-wave optics in signal processing and sensing

Research in the use of guided-wave optics for signal processing and sensing is reviewed, and advantages and limitations of the technology are discussed. The signal processors employ electrooptic, acoustooptic, and fiber-optic components to perform such functions as spectral analysis of radio-frequency signals, correlation and matched filtering, code and waveform synthesis, signal delay and storage, and analog-to-digital and digital-to-analog conversion. In most cases, the guided-wave approach is distinguished by the ability to perform a particular function at very high analog bandwidths or digital data rates. The second part of the review is concerned with sensor applications for guided-wave elements fabricated on planar substrates ("integrated optics"). Waveguides on an integrated optics chip have been used for sensing temperature, humidity, electric field, wavefront angle, and optical disc reflectivity. Also described are integrated optic phase and frequency shifters developed for use in fiber-optic sensors. In concluding remarks, an effort is made to provide some perspective on competing technologies and to indicate some areas where future research might prove fruitful.