Radiation testing of 25 Gbaud balanced photoreceivers with bismuth ions for linear energy transfer up to 70 MeV cm2/mg

Space-based optical communication links incorporating high speed photoreceivers, i.e. photodiodes integrated with Transimpedance Amplifiers (TIA), are required for multiple platforms, from low earth orbit satellite communication constellations to inter-planetary links and deep space missions. Our prior studies have demonstrated that InP/InGaAs photodiodes are resilient to radiation induced displacement and ionization damage when irradiated with a wide variety of ions. It is also necessary to qualify TIAs that may exhibit latch ups due to Single Event Effect (SEE) when irradiated with heavy ions having high Linear Energy Transfer (LET). We present a balanced InGaAs photoreceiver, i.e. a matched pair of photodiodes followed by a Silicon CMOS TIA, with automatic gain control mode that supports coherent and direct detection optical communication links with a symbol rate up to 25 Gbaud and aggregate data rate up to 100 Gbps and beyond. These devices were subjected to 76 MeV/n, 96 MeV/n, and 154 MeV/n Bismuth Ions up to a fluence of 1E7 ions/cm2 for each ion energy. The ion energies were chosen with the objective of achieving LET-Si of ⪆70 MeV-cm2 /mg. During the radiation runs, the TIAs were biased and their drive currents and RF output noise spectra were continuously recorded. The in-situ data was complemented by detailed analog and digital characterization of these devices before and after irradiation, including photodiode dark current, TIA drive current, RF response, RF return loss, noise spectrum, 25 Gbps Amplitude Shift Keyed (ASK) eye diagrams and bit error ratio, and 10.709 Gbps Return to Zero Differential Phase Shift Keyed (RZ-DPSK) eye diagrams and bit error ratio. We did not observe any significant impact on these devices due to radiation.