Electro-optic properties of potassium hydrogen phthalate crystal and its application as modulators

Potassium hydrogen phthalate crystal is a good nonlinear optical system. Its electro-optic coefficient r(131) is measured for a wavelength of 670 nm and it is found to be of the order of that of urea crystal (1.06 pm V-1). The dispersion study for the effective Pockels coefficients r(eff) = r(113) - r(112), is carried out for this crystal, and the electronic part of the electro-optic coefficient is shown to play an important role in the potassium hydrogen phthalate crystal. The electro-optical dispersion birefringence constant is found to be - 1.11. Modulators based on KAP possess good figure of merits. The figure of merit that has been measured, corresponding to the wavelength of 670 nm is 9.5 pm V-1.