updated 10:10 pm EDT, Mon April 30, 2012
Colloidal quantum dot construction revolutionized
Researchers at Brown University have uncovered a new method of producing a polychromatic laser. A new material has been produced that, in conjunction with a monochromatic laser, is capable of producing laser light simultaneously in the red, blue, and green (RGB) wavelengths. This new material points the way towards multi-wavelength, single-material lasers for commercial utility.
Most lasers used in commercial applications are semiconductor-based. This new technique uses a thin film known as a colloidal quantum dot (CQD). A CQD produces laser light not only in relation to the construction material, but also by the size of the dot -- the larger the dot, the longer the wavelength. Until recently, CQD lasers have not been practical. Using a not-fully-detailed construction technique, the electronic properties of the CQD film was changed, prioritizing laser emission over the normal heat generation that has typically ruined CQD films tested for laser emission.
A standard monochromatic laser used to excite the film produced by Brown's new method produced three discrete wavelengths of laser production. A filter was applied to the produced laser light to remove the wavelength from the original laser and only the CQD photons remained, proving the methodology.
Even though the original experiment was done at room temperature and pressure, the process isn't ready for commercial application as of yet. Multichromatic semiconductor lasers exist, but are complex and expensive to construct. Theoretical uses for small, easily produced polychromatic lasers include increasing the bit density on optical media, advanced video displays, astronomical applications, military range finding both underwater and over land, and industrial uses.