Seminar Announcement: Sachin Kumar Maurya

Data pubblicazione: 28-ott-2025

Announcement
Thursday, 30 October 2025, 15:00
Sala Grande Palazzina B via alla Cascata 56/C

"Upconversion Enhancement in Lanthanide-Doped Sol-Gel Photonic Crystals for White Light Generation"

Dr. Sachin Kumar Maurya
Centro de Química Estrutural,
Institute of Molecular Sciences and Departamento de Engenharia Química, Instituto Superior Tecnico,
Universidade de Lisboa,
Av. Rovisco Pais,1,
1049-001, Lisboa, Portugal

Abstract
This study uses the sol-gel (SG) method, a cost-effective and flexible liquid phase processing technique, for the fabrication of one-dimensional (1-D) photonic bandgap structures, namely Bragg mirrors (BMs) and Fabry-Perot microcavities (F-P MCs). The study begins with the formation of highly reflective quarter-wave multilayer stacks composed of alternating layers of high refractive index titania and low refractive index aluminosilicate glass thin films. In particular, 1-D MCs have been prepared by spin-coating suitable sols on Si and silica glass substrates; these included lanthanide-doped (Tm3+, Er3+, Yb3+) aluminosilicate and neat titania sols, designed for MCs with pass band defects at 500, 625, 650 and 700 nm at normal incidence reflection. Several techniques were utilized to characterize such multilayered structures, including Spectroscopic Ellipsometry, FTIR, variable angle specular reflection and 980 nm laser-excited up-conversion (UC) photoluminescence (UCPL) spectroscopy. Laser power dependence studies have been performed to assess the UC mechanisms and CIE chromaticity diagrams were used to characterize the visible light emitted by the MCs. The CIE color coordinates are affected by changing the UCPL detection angle. The present research clearly demonstrates the versatility and effectiveness of SG-derived 1-D photonic crystals in lanthanide-doped optoelectronic materials and devices, allowing the preparation of optimized optical structures with tunable properties for future photonic applications.