Practical, tunable 3-D microdroplet laser

Electronics could get smaller, faster, cheaper to make and higher in precision, thanks to a microdroplet 3-D laser system.

“This is the first practical 3-D laser ever produced,” said Igor Musevic, who developed the laser with Matjaz Humar at Jozef Stefan Institute. The microdroplet lasers will be used to make arrays of coherent light emitters for a variety of imaging purposes, including internal-source holography, Musevic said.

In the system, laser light shines in all directions from dye molecules inside spherical drops of helical molecules – cholesteric liquid crystals – that are dispersed in liquid. The cholesteric liquid crystals are incompatible with the surrounding polymer liquid, causing their index of refraction to vary periodically outward through the body of the 15-μm-size droplet. The droplet could be compared to an onion, where the layers correspond to materials with a different index of refraction; this nested sequence of onion-layer regions of changing index of refraction functions as the laser’s resonant enclosure instead of as a mirrored cavity.

The laser components are self-assembled spontaneously through chemistry, and the laser can be tuned by changing the pitch size of the helical molecules with a change in temperature or with the addition of an extra electric field.

The report appears in Optics Express, Vol. 18, Issue 26, pp. 26995-27003 (2010).