Proton and gamma radiation testing of 10 GHz bandwidth, uncooled, linear InGaAs optical receivers

We have successfully tested 10 GHz bandwidth, uncooled, linear InGaAs optical receivers, coupled with a standard single mode fiber for proton and gamma rays. These devices find multiple applications in space for inter-satellite optical communication links, rapid Doppler shift lidar, as well as inter-planetary and Earth-to-Moon communication links. Nine InGaAs PIN photodiode and GaAs transimpedance amplifiers (TIA) were irradiated with 100 MeV protons with a fluence level of 1.6 × 10¹¹ cm^-2 corresponding to a total dose of 19.1 krad (water). Devices were also subjected to 30 MeV protons, six each with fluence levels of 4.9 × 10¹⁰ cm^-2 , 9.8 × 10¹⁰ cm^-2 , and 1.6 × 10¹¹ cm^-2 . Additionally, another nine InGaAs optical receivers were irradiated with 662 keV gamma rays, three devices each for a dose of 15 krad (water), 30 krad (water), and 50 krad (water). Pre- and post-radiation results were measured for (1) dark current vs. voltage for the InGaAs photodiodes, (2) responsivity (quantum efficiency) for the photodiodes, (3) optical return loss at 1550 nm wavelength, (4) drive current of the TIA, and (5) bandwidth of the PIN + TIA. All devices were found to be fully functional at the normal operating conditions and at room temperature.