A modulator includes a modulator body, a transparent conductive film, a power supply and a current detection assembly, the modulator body includes an internal electrode and a gold foil layer disposed opposite to each other, and a liquid crystal layer disposed between the internal electrode and the gold foil layer; the transparent conductive film is disposed on a surface of the gold foil layer away from the liquid crystal layer, and a gap is formed between the transparent conductive film and the gold foil layer; the gold foil layer and the transparent conductive film are electrically connected respectively to terminals of different polarities of the power supply, and the current detection assembly is connected in series between the gold foil layer and the power supply, or the current detection assembly is connected in series between the transparent conductive film and the power supply.