Embodiments of the present disclosure are directed toward techniques and configurations for an apparatus comprising an electro-optical modulation device with a bias control and adjustment. In some embodiments, the apparatus may comprise an electro-optical modulator having first and second arms, to modulate light passing through the first and second arms in response to an input data signal, and output a corresponding optical data signal. The apparatus may further comprise a control module coupled with the electro-optical modulator, to differentially adjust respective phases of first or second light portions passing through the first and second arms, to achieve a bias point for the optical data signal. The bias point may define a desired power output of the apparatus that corresponds to the optical data signal. Other embodiments may be described and/or claimed.