Radiation hardness of semiconductor laser diodes for space communication

Semiconductor laser diodes (LDs), with merits of little volume, lightweight, low power consumption, ease of modulation, and high data rates, are great candidates for space laser communications. However, operating in a radiation environment can result in various damages to LDs. Hence, the growing focus on satellite laser communications necessitates LDs with improved radiation hardness. This review covers the efforts made in investigating the radiation effects on LDs induced by various types of radiation, including neutrons, γ-rays, protons, electrons, and other radiation particles. The conditions of radiation experiments and the behaviors and mechanisms of the degradation of LD material and device performance after being radiated are surveyed and discussed. It has been revealed that quantum dot (QD) LDs typically exhibit superior radiation tolerance compared to quantum well LDs or LDs with bulk active layers due to the enhanced confinement of carriers and reduced active areas in QD LDs, indicating significant potential for space applications. Furthermore, current challenges and issues in this field are discussed and addressed, providing a perspective and outlook for further research. Our review aims to guide the development of suitable light sources for future space laser communications, fostering high-performance satellite communications networks.