Optical coupling between high power lasers and photonic circuits for LiDAR applications

Silicon photonics was initially developed for high-performance telecommunications, but new applications quickly emerged. These include the development of LiDARs (Light Detection And Ranging) intended for environmental imaging for vehicles and autonomous systems. Indeed, existing LiDARs are made of discrete components whose mechanical assembly makes them fragile, expensive and bulky. By using a photonic chip, the current optical beam scanning system (moving mirrors) could be replaced by an integrated Optical Phased Array (OPA). To be able to detect objects located several tens (or even hundreds) of meters away, it is necessary to use a high-power laser because only a small amount of the emitted light will be redirected to the LiDAR. However, the few demonstrations of OPA based LiDARs rely on external lasers that are very expensive and incompatible with large-scale commercialization. Achieving an efficient coupling between a powerful integrated laser and a photonic chip is therefore of primary importance and has not yet been demonstrated by the community. Beyond LiDARs, the coupling of high optical power in a photonic chip would also find interest for many other applications: powerful mode-lock lasers, nonlinear optics, sensors, etc.

As part of the European H2020 VIZTA project, the CEA LETI is already working on this issue in collaboration with the III-V lab located in Saclay (France), which supplies the lasers. This thesis is therefore a continuation of this work that will be deepened by the candidate with the main objective of demonstrating an effective coupling between a powerful laser and a photonic chip, as well as complete demonstrator circuits. In parallel, several upstream studies will also have to be conducted by the candidate: evaluation of the power handling capabilities of photonic devices (non-linear effects), power mode-lock lasers, packaging constraints (alignment, heat dissipation, etc.). The main activities carried out during the thesis concern the design and simulation of photonic components, the monitoring of their manufacture and their electrical and optical characterization. To carry out the project, the candidate will have access to the calculation means and characterization benches available at CEA-LETI. The technological developments will be carried out on regular manufacturing runs via the 200mm photonic platforms of the CEA Grenoble.

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