Optical gain medium having doped nanocrystals of semiconductors and also optical scatterers
AssigneeBrown University Research Foundation
InventorNabil R. Lawandy
Life of this patent
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Abstract
An optical gain medium comprises a multi-phase system wherein: a first phase is an electromagnetic radiation emitting and amplifying phase (16) that is comprised of doped semiconductor nanocrystals; a second phase is an electromagnetic radiation scattering phase (14); and a third phase is a substantially transparent (at the wavelengths of interest) matrix phase (12). The emission phase may consist of ZnS nanoparticles that are doped with Mn.sup.2+, the scattering phase may comprise TiO.sub.2 or Al.sub.2 O.sub.3 nanoparticles, and the matrix phase may comprise a glass or polymer body, layer or coating. At least one dimension of a body, layer, or coating comprised of the gain medium may be less than a scattering length associated with the scattering phase.
Claims44
A structure that exhibits laser-like activity when excited by a source of excitation energy, the structure comprising in combination:
- a matrix phase that is substantially transparent at wavelengths of interest;
- a doped semiconductor nanocrystal electromagnetic radiation emitting and amplifying phase;
- and
- a high index of refraction contrast electromagnetic radiation scattering phase, wherein said matrix phase, said electromagnetic radiation emitting and amplifying phase, and said electromagnetic radiation scattering phase are commingled within a volume of said structure.
A device that outputs electromagnetic radiation within a first band of wavelengths when excited by electromagnetic radiation having wavelengths within a second band of wavelengths, the device comprising:
- a gain medium comprised of a matrix phase that is substantially transparent at wavelengths of interest, a doped semiconductor nanocrystal electromagnetic radiation emitting and amplifying phase, and an electromagnetic radiation scattering phase, wherein said matrix phase, said electromagnetic radiation emitting and amplifying phase, and said electromagnetic radiation scattering phase are commingled within a volume of said gain medium.
A method of broadening and shifting a band of emission wavelengths from a plurality of doped semiconductor nanocrystals, comprising the steps of:
- providing a sample comprised of a plurality of the doped semiconductor nanocrystals in combination with (a) a plurality of scattering particles or sites and (b) a medium that is substantially transparent to the band of emission wavelengths;
- irradiating the sample with electromagnetic radiation having wavelengths suitable for generating an emission from the doped semiconductor nanocrystals;
- and
- broadening and shifting a band of emission wavelengths from the plurality of doped semiconductor nanocrystals by scattering the emission with the scattering particles or sites.
A method for generating electromagnetic radiation, comprising the steps of:
- providing a sample comprised of a plurality of semiconductor nanocrystals that are doped with a selected dopant;
- irradiating the sample with electromagnetic radiation having energy suitable for raising electrons from a
- valence band to a conduction band of the doped semiconductor nanocrystals;
- and
- using the electromagnetic radiation to induce a Tyndall Resonance condition within at least some of the doped semiconductor nanocrystals such that a radiative decay rate of the selected dopant is increased.
A display device, comprising:
- a substrate;
- and
- a plurality of display pixels formed upon or within a surface of said substrate, each of said display pixels comprising a gain medium comprised of a matrix phase that is substantially transparent at wavelengths of interest, a doped semiconductor nanocrystal electromagnetic radiation emitting and amplifying phase, and an electromagnetic radiation scattering phase, wherein said matrix phase, said electromagnetic radiation emitting and amplifying phase, and said electromagnetic radiation scattering phase are commingled within a volume of said gain medium.
An optical emitter comprising:
- a substrate;
- and
- a first thin film disposed over a surface of said substrate;
- wherein
- said first thin film is comprised of a first optical gain medium comprised of a first optical emitter in combination with a plurality of scattering centers for emitting, in response to excitation by a pulse of electromagnetic radiation having a first range of wavelengths centered about a first wavelength, a first temporally and spectrally collapsed pulse of electromagnetic radiation having a second range of wavelengths centered about a second wavelength, wherein said first optical emitter is comprised of first semiconductor particles that are doped with a luminescent center.
Dependencies are inferred from the claim text.