Patent ID: 7983117

Claim:
A method for writing into a data memory at least one layer of a supporting material, said layer including molecules being capable of taking a collective state of molecules among at least a first collective state of molecules and a second collective state of molecules, said method comprising: applying an orientation electric field to said at least one layer, said orientation electric field being capable of putting said molecules in said first collective state of molecules; fixing said molecules in said first collective state of molecules; and selective application of a writing electromagnetic radiation to at least one writing zone of said at least one layer, said writing electromagnetic radiation being capable of generating a two photon absorption at said at least one writing zone, said two photon absorption switching said molecules of the first collective state of molecules to said second collective state of molecules in said at least one writing zone; with the molecules of two different collective state of molecules being capable of generating, when they are excited by a reading electromagnetic radiation, second-harmonic signals having a different intensity.