US Patent 7121474 - Optically Readable Nanocrystal Memory

http://www.freepatentsonline.com/7121474.pdf

There is much interest in interfacing electronic and optical devices to optimize the advantages of optical circuits (e.g. high bandwidth, no heat generation) with the advantages of electrical circuits (e.g. well established fabrication, high density integration) This patent proposes such a hybrid system that includes a nancrystal electrical memory readable via optical detection.
Claim 1 reads:

1. A method of reading a memory device, comprising: directing a beam of first photons onto an array of insulated nanocrystals formed proximate to a substrate; and sensing an optical response to the beam of the first photons from the array of insulated nanocrystals to determine whether the memory device is in one of a first logic state or a second logic state, wherein the first photons have an energetic level equal to at least a band gap energy between a valence band and a conduction band of the insulated nanocrystals and wherein the optical response includes second photons emitted from the insulated nanocrystals, an absence of a threshold amount of the second photons indicating that the memory device is in the first logic state, a presence of at least the threshold amount of the second photons indicating that the memory device is in the second logic state.