Advancements in integrated optics showcased at Photonics West Conference 2025

The recent Photonics West Conference 2025 showcased the significant advancements made by CEA-Leti scientists in the realm of integrated optics, with a particular focus on enhancing system efficiency while reducing size and costs across various applications. The conference provided a platform for the institute to present three papers detailing their innovative research and development in chemical detection, high-speed communications, and LIDAR performance, all utilising integrated optics on silicon.

Cyril Fellous, head of CEA-Leti’s Optics and Photonics Division, emphasised the emerging importance of integrated optics. “Integrated optics on silicon will play an increasingly vital role in many diverse and critical applications, because photonic integrated components are compact, easy to manufacture and they allow integration of advanced materials,” he stated.

One of the papers presented, titled “Design and Integration of Hybrid IIIV/Si Mid-Infrared Laser Sources and Photonic Circuits for Chemical Sensing Applications,” detailed the design, fabrication, and characterisation of groundbreaking hybrid III/V-on-silicon quantum-cascade lasers that operate within the 4 µm to 5 µm spectral range. The innovative architecture developed boosts the integration efficiency of these lasers in comparison to the traditional monolithic ‘full-III/V’ approach. Maxime Lepage, the lead author of the paper, noted, “Because all passive functions of the lasers, such as optical feedback, waveguide routing, and power transfer, are defined into the silicon, more degrees of freedom are allowed for the design.” He further highlighted the emerging relevance of chemical sensing within the context of mid-IR silicon-photonic devices, which are gaining traction in spectroscopy, material processing, security, and industrial applications.

Another key presentation was titled “Design of Grating Coupler with Large and Flat Illumination Far-Field Profile for FMCW Flash LiDAR,” which introduced a grating coupler design that consolidates critical optical functions, including beam separation and scene illumination, onto a photonic chip. This design facilitates vertical light emission while ensuring a wide field of view in both horizontal and vertical orientations—maintaining a consistent far-field illumination profile. Lead author Paul Camus described this development as “an integrated version of the illumination optics of an FMCW flash LIDAR,” indicating that it is a promising preliminary step toward a fully integrated FMCW flash LiDAR system. The compact and efficient LiDAR solutions presented could find applications in fields such as autonomous driving, facial recognition, and robotics.

A third significant paper titled “Towards Fully Integrated Frequency Comb Based Transceivers” reported on advancements in nonlinear photonics aimed at improving high-speed communications. This research involved the fabrication of ultralow-loss silicon-nitride (SiN) waveguides and components on 200mm wafers, enabling the generation of a frequency comb and the separation of its comb lines. The implications of this technology include a reduction in the costs and energy consumption of high-speed transmitters, as it enables the replacement of multiple lasers with a single frequency comb source. Optical frequency combs, characterised by discrete and stable wavelengths arranged at regular intervals, serve as multiple parallel laser sources, produced through nonlinear optical processes in materials like SiN.

Overall, the presentations at Photonics West 2025 underline the pivotal role that integrated optics on silicon is set to play in developing compact, efficient technologies tailored for a variety of critical applications spanning chemical detection, high-speed communications, and advanced LIDAR systems.

Source: Noah Wire Services