Exploring the Optical Nonlinearity in Zr<sup>4+</sup> Codoped YPO<sub>4</sub>:La Nanostructures for Optical Limiting Device Applications
Vijayakumar Balakrishnan, Shanthi Simon, Mani Rahulan Kirubalan, Annie Sujatha Rajendran, D. M. Murugan, Sabari Girisun Chidambaram, N. Angeline Little Flower
Abstract
Advancement in optical limiters has become an extensive research hotspot for protection of optoelectronic sensors and human eyes from laser damage. Systematic investigation of structural, linear, and third-order nonlinear optical characteristics of Zr 4+ -codoped YPO 4:La nanostructures for efficient optical limiting are reported. Structural analysis and vibrational properties were confirmed via various characterization techniques, such as X-ray diffraction (XRD) and Raman and Fourier transform infrared (FTIR) spectroscopy. The surface chemical and electronic configuration of Zr 4+ -codoped YPO 4:La particles are determined by X-ray photoelectron spectroscopy (XPS) analysis. High-resolution scanning electron microscopy (HR-SEM) determines the spherical morphology, and transmission electron microscopy (TEM) confirms polycrystalline nature. Investigation of linear optical properties includes analysis of absorption spectra, emission spectra, and the excited state lifetime. An open aperture (OA) Z-scan study aided by a pulsed laser source operating at 532 nm reveals the reverse saturable absorption (RSA) property of the orthophosphate sample. Intensity-dependent Z-scan studies reveal the existence of excited state absorption. The nonlinear absorption coefficient (β) is calculated and is on the order of 10 –11 m/W. Zr 4+ -codoped YPO 4:La nanoparticles exhibit enhanced optical limiting action as a consequence of strong effective two photon absorption (2PA) assisted by excited state absorption (ESA).