Unsustainable energy consumption
Artificial intelligence is set to change our society for the better. Still, the energy consumption for using and training the algorithms is staggering and not sustainable in a global perspective. Similarly, the power consumption in data centers serving social media or streaming content is a large and, more importantly, an increasing fraction of the total electricity used.
Most of the consumed energy is used for transporting information around, exacerbated by the need to cool the computer chips. It is well known that photons are much better than electrons for communication, as evidenced by the widespread use of optical fibers for the internet. However, when shrinking things down to the size of electronic chips it is not only the relative performance between the technologies that matter but also the absolute power consumption. Conventional lasers are large and emit millions of photons, which is much more than is needed to signal a bit across a chip. It has been a major challenge to make the lasers small enough that they, on an absolute scale, use less power than the equivalent electronic wire.
Record-breaking laser
The newly developed laser at DTU Electro can be modulated at a typical processor speed, while consuming less than a femto-Joule for each bit! Such a laser can enable on-chip links with ultra-low power consumption below 1/100 of the energy used for a short link in today’s chips. This result was achieved by a combination of very advanced nanotechnology developed by several PhD students over the last 10 years, and an improved understanding of the device limitations, which led to an optimized design.
Vision
First author Evangelos Dimopoulos says: "We are thrilled to achieve this important milestone and to contribute to the novel field of nanolasers. This is a very promising technology that can revolutionize computing and help us move towards a sustainable and green society. Our team worked hard to develop and understand the properties of these lasers, including the role of doping in reducing the quality of the laser cavity (the storage time for photons). Utilizing this knowledge, we managed to shrink the gain medium efficiently, realizing a laser threshold of a few hundred nanoAmperes. We now have an excellent platform to experiment and test new ideas that will help us shed light on laser physics at the nanoscale!".
Professor Kresten Yvind adds: "The complexity of these types of optoelectronic devices is almost too high as it is only NTT in Japan and us who have been able to make them so far. The next step is to shrink them even more so the capacitance becomes comparable to state-of-the-art electronics. This way one can intimately couple the electronic and photonic domains with large gains to both. This is the main vision for the NANOPHOTON center".
Facts
The foundation for the work was done in the Villum Center of Excellence on Nanophotonics for terabit communication (NATEC) and continues in NanoPhoton – Center for Nanophotonics, which is financed by the Danish National Research Foundation, both led by Professor Jesper Mørk.
Original work
- Authors: Evangelos Dimopoulos, Meng Xiong, Aurimas Sakanas, Andrey Marchevsky, Gaoneng Dong, Yi Yu, Elizaveta Semenova, Jesper Mørk, and Kresten Yvind
- Title: Experimental Demonstration of Nanolaser with sub-μA Threshold Current
- Journal: Optica Vol. 10 Issue 8, pp. 973-976 (2023)
