First Mass-Manufacturable Submicron Disk Laser

Professor of applied physics, Hui Cao, in collaboration with researchers at Northwestern University and NIST, has developed the first submicron disk laser using standard photolithography and wet chemical etching – a simple fabrication technique apt for mass production.

 

Researchers are continuously looking for ways to make lasers smaller as applications develop for nanophotonic circuits, on-chip optical interconnects, and fine-resolution chemical and biological sensing. In order to do this, they must find ways to confine or trap light in smaller and smaller cavities. There are different ways of doing this; one way is the semiconductor microdisk of circular shape. Until recently, researchers had been unable to reduce the size of the microdisk below 1 μm in diameter.

 

With a diameter of 627 nm, Cao’s submicron disk laser is not only the smallest reported to date, but the only disk laser in which the vacuum lasing wavelength exceeds the disk diameter. One other group has reportedly achieved submicrometer (not subwavelength) disk lasers, but did so using electron-beam lithography – a time consuming and expensive technique. “Not only have we made the smallest microdisk laser,” says Cao, “but we found a way to make it using standard photolithography and wet etching so that it will be easier to apply to mass production.”

 

While acknowledging that this is a significant achievement, Cao says they will continue to push the size smaller and look for new designs that would allow for ultra-small cavities without compromising confinement efficiency.

This work was published in the February 2009 issue of Applied Physics.