Alpha Radiation Effects on Silicon Oxynitride Waveguides

Photonic technologies are today of great interest for use in harsh environments, such as outer space, where they can potentially replace current communication systems based on radiofrequency components. However, akin to electronic devices, the behavior of optical materials and circuits can be strongly altered by high-energy and high-dose ionizing radiation. Here, we investigate the effects of alpha (α) radiation with MeV-range energy on silicon oxynitride (SiON) optical waveguides in the 1550 nm wavelength range. Irradiation with a dose of 5 × 10 15 cm –2 increases the refractive index of the SiON core by nearly 10 –2, twice as much as that of the surrounding silica cladding, leading to a significant increase of the refractive index contrast of the waveguide. The higher mode confinement induced by α-radiation reduces the loss of tightly bent waveguides. We show that this increases the quality factor of microring resonators by 20%, with values larger than 10 5 after irradiation.