Researchers in the Department of Electronic and Electrical Engineering at UCL have collaborated with the London Centre for Nanotechnology to introduce silicon-based information technology solutions at high speeds.
Quantum dot laser fabricated on a silicon substrate at UCL
The research details were published in the Nature Photonics journal. The research team has demonstrated a quantum dot laser that was driven electrically and grown on a silicon substrate directly having a wavelength of 1300 nm, the quantum dot laser is ideal for telecommunications applications.
Complete integration for silicon photonics can be achieved by directly growing compound semiconductor laser on silicon, but significant variations in crystal lattice constant between compound semiconductors and silicon leads to dislocations in the crystal lattice, thus resulting in short operating periods and low efficiency for semiconductor lasers.
The UCL team has overcome these challenges by forming a special layer, a quantum dot gain layer which can stop these dislocations from getting to the laser layer. The team worked with co-workers at the EPSRC National Centre for III-V Technologies, to grow a quantum dot laser on a germanium (Ge) substrate. The laser offers uninterrupted operation up to 70°C and continuous power output of more than 25 mW per facet.