A method of manufacturing a storage device for storing information, apparatus for storing information, an optical memristor device and a memory cell are disclosed. A method comprises providing at least one first electrode and at least one further electrode and providing each of at least one region of a first material between, and in electrical connection with, a respective first electrode and a further electrode whereby said step of providing at least one region comprises providing in the first material, a plurality of changeable particles that have charge storage capacity and at least one electrical property that is reversibly changeable responsive to absorption of incident electromagnetic radiation.