Recent Developments In SSB Modulators

A tutorial review of the principles of single sideband (SSB) electro-optic modulators is presented. Recent developments for broadbanding such modulators by multisection techniques and dual tandem arrangement is described. The discovery and use of crystal rotational orientation effects on the performance of multicrystal configurations is considered. The techniques for the theoretical treatment using coupled-mode equations for both multicrystal arrangements are developed. The results of theoretical calculations are presented in graphical form. These demonstrate the enhanced capabilities in terms of efficient conversion and increased bandwidths. Wherever possible, comparison of theory and experiment will be presented. The enhanced performance at 10.6 μm and at 1.06 μm available high quality crystals will be reviewed. The choice of crystals for each wavelength region is based on the physical properties such as symmetry, dielectric constant, electro-optic coefficient, optical and microwave losses. These parameters are incorporated in the theory and practical considerations of availability and quality required for optimum performance.