Crystallization of Y3Fe5O12 thin films on silicon photonic waveguides using CO2 laser annealing

Abstract

We report the local crystallization of Y3Fe5O12 (YIG) thin films grown on Si substrates, and SOI waveguides by CO2 laser annealing (LA). The effect of laser power and oxygen pressure on the crystal structure of YIG films was systematically studied. Laser power dominated the YIG film crystallinity, while oxygen partial pressure during LA strongly influenced the crystal grain size and magnetic anisotropy. Fully crystallized YIG thin films with pure garnet phases were fabricated by LA. The refractive index n and extinction coefficient k were comparable to thin films fabricated by rapid thermal annealing (RTA). Propagation loss measured at 1550 nm wavelength on YIG/SOI waveguides and YIG/SiN ring resonators were comparable to RTA annealed films, promising device development for silicon photonics.