US Patent 7560707 - Plasmonic up-converter

http://www.freepatentsonline.com/7560707.html

Up-conversion materials provide a conversion from infrared to visible light offering an alternative to cathode ray tubes and LCDs for a lighter display structure. This patent from Hewlett-Packard teaches using surface plasmons formed in a nanostructured surface to increase the efficiency of such materials. Claim 1 reads:

1. A plasmonic up-converter apparatus, comprising:

an excitation source operable to emit electromagnetic radiation at an excitation frequency; and

at least one array of nanofeatures configured to produce an emission spectrum responsive to irradiation with the electromagnetic radiation, the emission spectrum having a number of distinct emission peaks, wherein a first emission peak is associated with a fundamental harmonic frequency, a second emission peak is associated with a second harmonic frequency, and a third emission peak is associated with a third harmonic frequency, the fundamental harmonic frequency approximately equal to the excitation frequency and the second and third harmonic frequencies greater than the fundamental harmonic frequency.