Investigation of the parameters of laser radiation modulators utilizing the Franz-Keldysh effect

A comparative analysis is made of the parameters of electrooptic light modulators utilizing the Pockels and Franz-Keldysh effects, and designed for the use in integrated optics systems made of gallium arsenide. It is shown that the use of a Franz-Keldysh modulator in integrated optics systems makes it possible to reduce considerably (by more than one order of magnitude) the modulator dimensions and, consequently, reduce the control power and increase the pass band of the modulation frequency. The results are given of an experimental investigation of a macroscopic analog of a film Franz-Keldysh modulator fabricated from high-resistivity gallium arsenide. It is shown that the depth of modulation can reach 60-90% in control fields up to $5\times10^4$ V/cm applied to a modulator $150\mu m$ long.