Analysis of Optical and Electrical Single-Event Transients in Integrated Silicon Photonic Microring Modulators

The single-event-effect (SEE) responses of microring modulators (MRMs) are evaluated. Charge was introduced using a pulsed-laser system capable of locally injecting electron-hole pairs (EHPs) via two-photon absorption (TPA). Both electrical single-event transients (SETs) and optical single-event transients (OSETs) were collected for different input wavelengths, anode biases, and laser pulse energies (PEs). Laser-equivalent linear energy transfer (LETL) threshold sensitivity, SET amplitude, and SET duration, were found to be highly dependent on the operational bias. Wavelengths in and around resonance conditions, typically heavily used operating conditions for MRM applications, exhibit the highest OSET sensitivity. Reasons for, and implications of, these bias dependencies are analyzed through free-carrier-plasma-dispersion (FCPD) theory and literature on pump-probe experiments in photonic ring structures. Analysis supports transients occur due to changes in the refractive index incurred during carrier injection, as well as thermal generation from free-carrier absorption (FCA). OSETs are observed down to a minimum PE = 207 pJ, corresponding to an LETLof 5.2 MeV • cm2• mg−1, relevant for space environments and orbital applications. Contrary to existing literature claims, the theory, data, and analysis presented in this work suggest that not all photonic components are SEE-resilient, with MRMs exhibiting the highest OSET sensitivity of any photonic component reported to date.