Space radiation effects on photonic integrated circuits for optical satellite payloads

Abstract

Photonic integrated circuits are a promising technology for space applications, particularly for future high throughput optical satellite links. They can be employed in optical communications terminals to integrate both active and passive devices such as photodiodes, filters, lasers, and modulators. However, the effects of the space environment, and of radiation in particular, on integrated optical devices still need to be better understood. The development of the current technology was driven by fiber-optic communications in terrestrial applications. For the application in space, changes are needed to adapt the same technology to the space environment. We present developments towards the demonstration of a coherent transceiver for satellite optical communications and ranging. Total ionizing dose tests were performed by measuring SiN integrated devices before and after exposure to a Co-60 source, and the permanent impact of irradiation was evaluated. The results show only a relatively small change in optical properties, such as effective index. Nevertheless, these changes could still be detrimental in sensitive devices. The irradiation effect is modeled and simulated to study its impact already at the design phase, and the potential changes on an integrated demultiplexer are discussed. Furthermore, thermal annealing is used to partially revert the changes induced by radiation.