Radiation-Induced Transient Response Mechanisms in Photonic Waveguides

A computationally efficient approach for estimating the impact of a 3-D distribution of carriers on an optical signal propagating within a waveguide is outlined and incorporated into a carrier transport solver to model the optical response as the carriers diffuse within the waveguide. It is shown that as the ionizing particle passes though the waveguide, the transmission will sharply drop, partially recover on the order of picoseconds, and then continue to recover as carriers recombine or escape the waveguide. The transient optical responses of a photonic waveguide can be incorporated into a photonic integrated circuit solver to demonstrate the spatial sensitivity of the radiation-induced transient optical response of a Mach-Zehnder modulator. The impact of the initial distribution of carriers injected into a photonic waveguide during single-event effects (SEEs) testing on the transient optical response is examined to assess the impact of using alternative SEE testing techniques to emulate ionizing particles. Since the transient optical response will depend on both the peak carrier density and total carriers injected into a waveguide, testing with larger carrier distributions will have difficultly matching both the transmission drop and recovery. Due to the reliance on carrier distributions with a larger spatial extent and fewer peak carrier densities than an ionizing particle, care must be taken when using alternative SEE testing techniques to not overestimate the SEE susceptibility of the photonic devices.