One of the major challenges of reducing modern day semiconductor power consumption has been our reliance on copper wire for data transfers. Past a certain point, copper simply doesn’t work well — it’s size can only scale to a certain point (which we’ve mostly reached), and past a certain point, making wires smaller also raises their electrical impedance. This means you end up with a higher level of resistance inside the chip, and resistance translates directly into higher heat. Now, scientists have demonstrated a new laser technique that can transfer data far more efficiently using a germanium-tin laser.
Laser-based data transfer has been a holy grail for the interconnect business for years. As wires become smaller, it also becomes more difficult to lay them properly — we actually covered a new technique for depositing copper inside a chip last year — but such manufacturing tricks are taking longer to develop and offer less scaling than they used to. The ability to move data using light doesn’t just offer a huge potential performance boost, it could also dramatically reduce power consumption. According to Professor Detlev Grützmacher, clock signals consume more than 30% of the energy required to move data inside a modern processor — which gives some idea of just how much power could be saved long term.
Silicon photonics and laser types
This new germanium-tin laser is different from the silicon photonics research that Intel has been researching for the past decade. Most obviously, it doesn’t rely on silicon or the heterogeneous integration of III-V lasers built on a silicon substrate (we’ve covered the evolution and research into III-V materials for semiconductor manufacturing elsewhere on ExtremeTech).