Radiation Effects on Si-Photonics-Integrated Passive Devices: Postirradiation Measurements

We discussed the X-rays permanent radiation effects on a variety of passive components developed using the silicon photonics platform of CEA-Leti. The objective is to assess the vulnerability of such devices at different total ionizing dose (TID) levels to provide an overview of the main radiation effects in this class of components. In detail, we have irradiated at room temperature grating couplers, microring resonators (MRRs), Mach-Zehnder interferometers (MZIs), Echelle grating de-multiplexers at five different doses, from 152 Gy(Si) to 1.52 MGy(Si) with similar to 40 keV X-rays. In the following, we first discuss the extraction of an important parameter for the study of photonics technologies under irradiation, the so-called "permanent radiation-induced attenuation" (RIA) of different geometries of silicon-integrated waveguides: strip, mid-Rib (mRib) and deep-Rib (dRib). Our results show that the geometry of the mRib waveguide presents the best radiation tolerance, with permanent RIA below 1.5 dB/cm, while the other architectures of guides exceed 2 dB/cm. Directional couplers (DCs), microring resonators, MZI and Echelle grating de-multiplexers show very good tolerance to high TID irradiations up to 1.52 MGy(Si), and no relevant permanent radiation-induced changes were observed for all of these passive devices. Such a finding is a good start to investigate in the future the eventual transient effects through in situ measurements and their recovery mechanisms.