Mercury Cadmium Telluride: an innovative material for upscaling

CEA-Leti teams built on their expertise of Avalanche Photodetectors (APD) in order to create a unique Mercury Cadmium Telluride (MCT)-based photodetector that is capable of detecting single photons. By building on the unique capabilities of quantum bits (qubits), this technology offers interesting gains in terms of noise and bandwidth. “Currently, we can imagine applications in quantum telecommunications for Free Space Optics (FSO), fiber optics and LIDAR," says Johan Rothman, Phd, CEA Fellow for infrared detection.​

One of the key challenges of this technology has been the required operating temperature for a photon detector. Using MCT, CEA-Leti researchers were able to create a photon detector that can operate at -190°C. “This may seem like a cold temperature, but it's in fact 40 times warmer than current superconducting technology," adds Johan Rothman. “This operating temperature is much easier to achieve outside the laboratory and greatly facilitates the use our photon detectors for real-life applications."

Superconducting Single Photon Detectors: integrating state-of-the-art performance​

While SSPDs currently offer the best performance in terms of photon detection, they have been hard to integrate into applicable technology because their production process required a unique set of technological tools. Alexei Tchelnokov, Chief Scientist for the Optics and Photonics Department, explains: “This production barrier meant that SSPDs could only be made at small scales for a high cost. At CEA-Leti, we were able to overcome this challenge by integrating the production process within our large 200mm cleanroom. As a result, the production and optical waveguides for integrating SSPDs can now be carried out using standard silicon photonics equipment – an achievement that opens the door to producing and integrating SSPDs at a much larger scale."

CEA-Leti photonics: a complete package for disruptive innovation​

The work on both of these detectors highlights one of the key advantages of the CEA-Leti photonics department: “We have the ability to produce and test both types of detectors in order to find the best one for each application and fine-tune its performance," highlights Ségolène Olivier, Integrated Quantum Photonics Program Manager at CEA-Leti. The same goes for the entire photonics value chain: “CEA-Leti has a long history in the field of silicon photonics. We can offer expertise on all the various building blocks used for silicon photonic circuits, from photon detectors to ring cavities, low-loss optical waveguides, low-loss optical modulators and low-loss beam splitters," adds Alexei Tchelnokov. By combining these cutting-edge building blocks, CEA-Leti provides partners with the ability to create tailor-made photonics chips that can support state-of-the-art applications such as quantum computing and quantum cryptography as well as current applications such as LIDAR or Free Space Optical Communications.