Integrated photonic chips, generally fabricated on silicon, do not perform well enough for demanding applications like LiDAR or processors for computing. Silicon's limitations have spurred the development of photonics on other substrates, such as silicon nitride (Si3N4). CEA-Leti has been investigating photonics on silicon nitride, a material with some potentially advantageous properties, for several years now. The technology is now mature enough to scale up for the production of photonic chips for R&D applications that will be made available to outside labs.
At just a few dB per meter, the propagation losses measured on silicon nitride optical waveguides are much lower than the 1 dB per centimeter observed on silicon. CEA-Leti's chips, fabricated to a very high quality standard, also offer much lower absorption coefficients. These properties enhance performance on a number of levels, boosting the maximum power that can be injected into the waveguides and enabling a wider range of wavelengths than silicon, typically from the visible to the mid-infrared.
In addition, improvement to silicon nitride deposition techniques have enabled CEA-Leti to develop a library of validated, reproducible components—the foundation for more complex circuits. LiDARs, for example, have already been produced successfully. The silicon nitride photonics platform is operated at the CEA as part of the Carnot Quantique QPIC and ANR SPHYFA projects on quantum communication systems.