As silicon chips keep getting faster, the copper connections used to transmit electrical signals between them are finding it hard to keep up. Optical signals are the obvious next step, but integrating them with silicon systems is difficult.
Researchers in UCL’s Electronic and Electrical Engineering Department and the London Centre for Nanotechnology successfully produced “the Holy Grail of silicon photonics” – an efficient laser for telecommunications, grown on a silicon base. This could be a stepping stone to a single chip capable of electronic processing and photonic transmission. Learn more about the discovery in the video below.
Building this kind of laser requires careful positioning of different transition elements in a nano-size pattern. Siting this precise structure on a pure silicon base is tricky – like trying to fit pieces from two different-sized jigsaws together – and can cause the laser-structure to fail.
To overcome these difficulties, the group bridged the gap between the two spacing with gradated layers, easing the change from one spacing to the other. This technique produced a more robust and efficient laser.
In related work published in Nature Photonics and also involving the EPSRC National Centre for III-V technologies, the group have reported efficient lasers operating continuously at temperatures up to 65 degrees Centigrade fabricated on germanium substrates.This provides scope for integrating with the silicon/germanium substrates proposed for ultra high speed electronics.
Leader of the research that enabled the creation of these lasers, Royal Society University Research Fellow, Dr Huiyun Liu, said “Our additional work on germanium should also permit practical lasers to be created on the silicon/germanium substrates that are an important part of the roadmap for future silicon technology.”
Head of the Photonics group at UCL Engineering, Professor Alwyn Seeds, expanded on this, saying: “Our future work will be aimed at combining these lasers with waveguides and drive electronics leading to a comprehensive technology for the integration of photonics with silicon electronics.”