Electro-optical modulators (EOMs) are widely used components because they enable fast switching of narrow-band light sources by an electrical signal. Recently, EOMs for wavelengths below λ = 1000 nm have attracted great interest for use in integrated photonics with applications such as optogenetics or biophotonics [1,2]. A Fabry-Pérot type EOM allows for very compact implementation on the basis of thin films [3,4]. This concept enables mass production for hybrid integrated optical circuits. Additionally, it implies orders of magnitude shorter interaction length between light and active medium compared to Mach-Zehnder type EOMs, the latter being based on waveguides from the active material. We explore modulation properties of materials with promising electro-optic (EO) coefficients in the double-digit pm/V range at the short end of near infrared wavelengths, not accessible by silicon photonics [5]. In contrast to the striking advantages of these materials, they exhibit non-zero losses due to intrinsic absorption or scattering, which is why shorter interaction lengths are beneficial.