Silicon Quantum Dot Laser Patent Information
Source/Type: Astralux Incorporated - White Papers/Technical Papers

September 24, 1996...

Inventors: Pankove, Jacques I. (Boulder, CO); Moddel, Garret R. (Boulder, CO); Douglas, Kenneth (Boulder, CO)
Assignee: The Regents of the University of Colorado (Boulder, CO)
Appl. No.: 473523
Filed: June 7, 1995

PATENT SUMMARY

An object of the present invention is to provide apparatus and methods to dynamically vary or control the color of light emitted by a silicon quantum dot laser. Such capability provides greater utility for the laser, for example as a pixel in a color display for moving images.

In order to accomplish this object, a plurality of first-sized quantum dots is provided to produce a first color of light, a plurality of second-sized quantum dots produce a second color of light, and a plurality of third-sized quantum dots produce a third color of light. Means for causing the first-sized dots, the second-sized dots, and the third-sized dots to produce varying amounts of light allows a variety of colors to be perceived by the human eye. The device emits light perpendicular to its surface. The light is resonated in order to make it coherent.

Apparatus in accordance with this invention produces dynamically varying colors of light employing a plurality of first-sized quantum dots for producing a first color of light which are selectively caused by a first controller to produce a varying amount of light. A plurality of second-sized quantum dots are arranged for producing a second color of light in varying amounts as selected by a second controller. Yet another plurality of third-sized quantum dots produces a third color of light in varying amounts as selected by a third controller. At least a portion of the first and second colors of light or of the first, second, and third colors of light: is then extracted from the apparatus.

This apparatus can include an arrangement for resonating the produced light for stimulating coherent light emission. The extracted light is that which is normal to a surface of the apparatus.

The light extraction is performed in one embodiment by sectors of concentric circular grating, the spacing of said grating sectors being a function of the light extracted. Preferably the grating sector spacing is proportional to the wavelength of the light extracted.

The controllers can stimulate the associated quantum dots via contacts for selectively voltage biasing those quantum dots. The quantum dots can take the form of a crystalline silicon with a lasing layer formed of the crystalline silicon dots in a hydrogenated silicon isolation matrix.

More particularly, the present invention produces dynamically varying colors of light via a lasing layer formed of crystalline silicon quantum dots formed in an isolation matrix of hydrogenated silicon. These dots are formed in three patches having different sized dots to produce three different colors of light. The device further includes a barrier layer of p-type silicon carbide under the lasing layer, a substrate wafer under that barrier layer, an n-type silicon carbide layer above the lasing layer, and a positive contact beneath the substrate. Three negative contacts, one above each patch of different sized dots acts with the positive contact to selectively bias the three patches.

Three sectors of concentric grating surround the lasing layer patches. These sectors have radial periods corresponding to the colors of light produced by the three patches for resonating photons emitted by the patches to stimulate coherent light emission. A dielectric mirror can be placed between the barrier layer and the substrate.

More particularly, the present invention produces dynamically varying colors of light from a plurality of groups of quantum dots with the dots of each group configured for producing a composite of light of a color different from the light produced by the dots of any other group. The dots of selected ones of the groups emit colored light therefrom. A plurality of optical resonance producing structures each provide optical resonance for a respective one of the dot groups.

The dot actuator includes an arrangement for introducing an input signal to each selected dot group with the input signal magnitude correlated to a predetermined amount of light from the selected group.

As is described in greater detail hereinbelow, the optical resonance producing structure preferably includes a plurality of optical grating segments. Each of those grating segments is positioned in proximity to a respective one of the quantum dot groups. Further, they are each sized for providing optical resonance for the proximal group for producing output light therefrom. The dot groups and the optical grating segments in proximity thereto are formed as segments of an arc around a central axis. Pairs of those arc segments on opposite sides of the central axis are configured for producing the same color light. It is believed a particularly useful array would thus include six of those arc segments arranged in opposite pairs of arc segments with the respective pairs producing red, green and blue light as outputs therefrom.

The dot group actuators can include a common electrode underlying all dot groups and a plurality of electrodes of equal number to the number of arc segments with each such electrode overlying a respective dot group. Thus, by applying a biasing signal to selected ones of the group overlying electrodes, those groups are enabled for light generation therefrom.

Those having normal skill in the art will recognize the foregoing and other objects, features, advantages and applications of the present invention from the following more detailed description of the preferred embodiments as illustrated in the accompanying drawings.

View the US Patent Office file

 Return to Search Results
Start a New Search

*****