Coin-size, On-chip Optical Sensors Prototype for Portable Devices Showcased at Photonics West

Posted Feb 07, 2019 by CEA-Leti

CEA-Leti, at the Photonics West event, has presented a prototype of next-generation optical chemical sensor using mid-infrared silicon photonics that can be integrated in smartphones and other portable devices.

Mid-IR chemical sensors operate in the spectral range of 2.5µm to 12µm, and are considered the paradigm of innovative silicon-photonic devices. In less than a decade, chemical sensing has become a key application for these devices because of the growing potential of spectroscopy, materials processing, and chemical and bio-molecular sensing, as well as security and industrial applications. Measurement in this spectral range provides highly selective, sensitive and unequivocal identification of chemicals. 

The coin-size, on-chip, IoT-ready sensors prototyped by Leti combine high performance and low power consumption and enable such consumer uses as air-quality monitoring in homes and vehicles, and wearable health and well-being applications. Industrial uses include real-time air-quality monitoring and a range of worker-safety applications.

Mid-IR optical sensors available on the market today are typically bulky, shoebox-size or bigger and cost more than €10,000. Meanwhile, current miniaturized and inexpensive sensors cannot meet consumer requirements for accuracy, selectivity and sensitivity. While size and price are not the most critical concerns for industrial applications, bulky and costly optical sensors represent a major barrier for consumer applications, which require wearability and integration in a range of portable devices.

CEA-Leti presented its R&D results at SPIE Photonics West 2019 in a paper titled "Miniaturization of Mid-IR Sensors on Si: Challenges and Perspectives". According to Sergio Nicoletti, lead author of the paper, Mid-IR silicon photonics has enabled creation of a novel class of integrated components, allowing the integration at chip level of the main building blocks required for chemical sensing. Key steps in this development extend the wavelength range available from a single source, handling and routing of the beams using photonic-integrated circuits, and the investigation of novel detection schemes that allow fully integrated on-chip sensing.

CEA-Leti's breakthrough combined three existing technologies necessary to produce on-chip optical chemical sensors:

  • Integrating a mid-IR laser on silicon
  • Developing photonic integrated circuits (PICs) in the mid-IR wavelength range, and
  • Miniaturizing a photo-acoustic detector on silicon chips.