Functionalization of optical fibers with rare-earth garnet single crystals for sensing applications

• Grant number: 25/14080-3
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: December 01, 2025
• End date: November 30, 2028
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Inorganic Chemistry
• Principal Investigator: Danilo Manzani
• Grantee: Leonardo Vieira Albino
• Host Institution: Instituto de Química de São Carlos (IQSC). Universidade de São Paulo (USP). São Carlos , SP, Brazil
• Associated research grant: 24/04675-7 - Remote Advanced Infrared optical fibers Sensors based on Soft glasses (RAISES), AP.R

Abstract

This project is dedicated to the development of an innovative luminescent sensor, obtained by integrating rare-earth garnet single crystals into optical fibers, aimed at chemical detection applications in the mid-infrared region. Rare-earth garnet crystals are particularly attractive for sensing applications due to their broad technological relevance in photonics, serving as laser hosts, magneto-optical devices, and scintillators. An innovative and scalable synthesis route based on conventional melt-quenching has enabled the reproducible production of micrometric single-crystal garnets. The goal of this project is to synthesize rare-earth garnet single crystals (Dy3+, Ho3+, Er3+, Sm3+, either individually or co-doped with Y3+) using this method for gas detection in the infrared region. Crystals will undergo comprehensive structural, morphological, and spectroscopic characterization, including X-ray diffraction, Raman and IR spectroscopy, SEM, and EDS analyses, with an emphasis on their luminescent properties and response to different gaseous analytes. The functionalization of commercially available infrared-transparent optical fibers will be achieved by attaching selected single crystals to the fiber ends using UV-curable optical adhesives. This "material transfer" strategy is chosen due to the comparable dimensions of the crystals and the optical fibers, enabling efficient mechanical and optical coupling. This method also offers experimental flexibility, cost-effectiveness, and minimizes thermal or mechanical damage to the fibers. The functionalized fibers will be tested for sensing performance, evaluating parameters such as emission stability, gas selectivity, response time, and durability, using external sources in the visible and near infrared along with mid-infrared spectrometers. The tests will include gases such as CH4, N2O, and CO2. The project will include a BEPE research internship with a research group at the Université de Bourgogne, France, partners in the FAPESP-ANR bilateral project to which this research is linked. This research is expected to significantly contribute to the development of luminescent materials and advanced optical sensors operating in the infrared region.