Micron-scale crystallization of Bi:YIG by laser rapid thermal annealing at controlled atmosphere

• A method of local laser annealing for the crystallization of Bi:YIG from oxide films obtained by metal–organic decomposition has been developed. • Bi:YIG laser crystallization was carried out in dry air, O 2 , N 2 and Ar atmospheres . • By-products of crystallization after annealing in O 2 , N 2 and Ar in the form of metallic Bi and Fe oxides were identified by Raman spectroscopy . • The largest Faraday rotation was found to be 2.6 deg/µm (at 500 nm wavelength) for a Bi 0.5 :YIG garnet film annealed in air. Rapid thermal annealing (RTA) at 800–900 °C in air atmosphere is commonly used to crystallize bismuth-substituted yttrium iron garnet (Bi:YIG) deposited by vacuum evaporation techniques or metal–organic decomposition. However, the conventional RTA leads to undesirable effects in applications where Bi:YIG is the constituent material of a nano- or microstructure. Here we report on an approach to Bi:YIG local crystallization by a focused continuous wave laser beam ( L RTA). The structural and optical properties of micron-sized Bi:YIG stripes crystallized in air, oxygen, nitrogen and argon atmospheres are discussed. The demonstrated LRTA can find practical applications for Bi:YIG monolithic integration on non-garnet substrates.