An optical device includes a first transparent substrate having a first transparent electrode disposed on a surface of the first transparent substrate and a second substrate having a second electrode disposed on a surface of the second substrate and facing the first transparent electrode. A liquid-crystal (LC) material is sandwiched between the first and second electrodes such that a voltage applied between the first and second electrodes controls orientation of the liquid-crystal material. The device includes a control system that applies a current through at least one electrode of the first and second electrodes to resistively heat the LC material.