Creating the laser of tomorrow

In response to needs arising from new technologies ranging from medicinal therapy to high-speed data communications, novel, high-performance aluminum-free diode lasers developed by Assistant Professor Luke Mawst (pictured) and Professor Dan Botez soon may replace their aluminum-based counterparts.

In current Al-based technology, the aluminum content in a laser's active region determines its wavelength; lasers that achieve shorter wavelengths require more aluminum. However, because aluminum-containing compounds in the active region are highly reactive, impurities such as oxygen can deteriorate the laser's reliability. Eliminating aluminum from the laser's active region improves its reliability, and removing it from the semiconductor layers around the active region makes it easy to fabricate complex high-performance diode lasers.

In an ongoing project funded by NSF and industrial grants, Mawst and Botez are growing InGaAsP-based materials on GaAs substrates using metalorganic chemical vapor deposition (MOCVD), and fabricating lasers using microelectronic processing technology. The resulting high-power prototypes are being tested in photodynamic therapies for cancer, atherosclerotic cardiovascular disease and age-related macular degeneration; and also to spin-polarize gases such as xenon or helium for use in a new form of magnetic resonance imaging (MRI), which has demonstrated image resolution of a million times greater than conventional MRI.

Mawst and Botez, of the Reed Center for Photonics, are collaborating with Princeton and Duke universities to develop and implement the Al-free laser sources, and Mawst also is developing Al-free vertical-cavity surface-emitting lasers for laser printing, optical recording and sources for data communications via optical fibers. Mawst, Botez and graduate student Tom Earles have started a spin-off company called Alfa Light based on the technology.