Optical fibre acoustooptic modulators

Coherent light propagating within an optical fibre may be modulated by using a piezoelectric transducer to stress the fibre mechanically. This paper discusses the design and evaluation of this type of optical modulator and compares a number of modulator designs. The paper demonstrates the relative roles of the mechanical properties of the fibre and the component parts of the transducer in determining the modulator performance and points out the differences in design philosophy between modulators employing monomode and multimode fibres. Finally, suggestions are made of ways of significantly improving modulator performance.