CO₂ laser assisted processing of (Ho_0.05Y_0.95)₂Ti₂O₇ coatings for infrared photonics

Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague 8, 182 51, Czech Republic

^* Corresponding author: podrazky@ufe.cz

Published online: 31 October 2024

Abstract

We demonstrated CO₂ laser assisted processing of highly transparent (Ho_0.05Y_0.95)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.