CO2 laser assisted processing of (Ho0.05Y0.95)2Ti2O7 coatings for infrared photonics

Abstract

We demonstrated CO2 laser assisted processing of highly transparent (Ho0.05Y0.95)2Ti2O7 nanocrystalline coatings. The amorphous coating of the thickness of 577 nm was prepared by subsequent spin-coating of a colloidal solution followed by densification at 700°C in a radiation furnace. The densified coating was irradiated by a laser beam of a power density of 20 mW/mm2 for 60 s to induce the crystallization process. The nanocrystals formation caused the densification of the coatings reducing the thickness to 490 nm and increased the refractive index to 2.088. The coating exhibited strong luminescence at 2.1 and 2.95 μm corresponding to 5I7→5I8 and 5I6→5I7 electronic transitions, respectively. The corresponding time-resolved luminesce records showed the single-exponential decay course reaching the values of 8.4 ms and 0.221 ms for the emissions recorded at 2.1 and 2.95 μm, respectively. The demonstrated process can be used to prepare a luminescent coating with tailored properties. CO2 laser assisted processing can be used in a manner of direct laser writing for the preparation of integrated optical waveguides and amplifiers as a powerful alternative to conventional thermal processing.