Blue microdisk lasers hit room temperature
Very small and efficient sources of blue laser light could now be on the horizon thanks to the demonstration of the first gallium nitride (GaN) microdisk laser to offer continuous operation at room temperature. In the January issue of Nature Photonics Adele Tamboli and colleagues reveal how they attain the lasing with blue (428nm) light at a threshold of 300 Watts per square centimetre – several orders of magnitude lower than previously reported devices. Until now, GaN microdisks have been limited to pulsed operation or have required cooling to low temperatures.Microdisk lasers are attractive future sources of light because they are potentially very efficient, small and emit from their top surface rather than the side. With their knowledge that small, smooth microdisks should offer ultra low thresholds, the researchers fabricated microdisks with a diameter of 1.2 micrometres using photoelectrochemical etching, and used electron beam lithography to create very smooth sidewalls.The development is a step towards the realization of tiny, efficient sources of blue light that could perhaps one day act as an alternative to the conventional edge-emitting semiconductor lasers found in CD and DVD players. But before this can happen, a scheme for directly electrically powering the lasers needs to be found as they currently need another laser as a pump source to power themselves.
Author contact:Adele Tamboli (University of California, Santa Barbara, CA, USA)Tel: +1 805 448 7560 or +1 805 893 4875; E-mail: atamboli@umail.ucsb.eduAdditional contact for comment on paper:Shuji Nakamura (University of California, Santa Barbara, CA, USA)Tel: +1 805 893 5552; E-mail: shuji@engineering.ucsb.edu