Advanced lanthanide doped upconversion nanomaterials for lasing emission

Microlasers are narrow-band and coherent light from small cavities, which have been widely applied in biomedicine, optical interconnection, integration devices, etc. Lanthanide doped upconversion materials are potential gain media for microlasers from near infrared (NIR) to visible and UV regimes due to their multi ladder-like metastable energy levels and superior optical frequency conversion capability. The optical feedback from photon scattering of the porous upconversion nanoparticles clusters has been reported to produce upconversion random lasers. The light bouncing back and forth between two reflective surfaces or internal surface has been utilized to achieve modulated upconversion lasing emission. In addition, photon lattices and plasmonic cavities with enhanced electromagnetic fields can amplify the upconversion process within the sub-diffraction volumes and produce highly efficient upconverting lasers. In this review, the recent advances on using lanthanide doped upconversion ma-terials for random, whispering gallery mode (WGM)/Fabry-Perot (FP) cavity and photon lattice/plas-monic cavity modulated upconversion microlasers are overviewed. Current challenges and future directions of the upconverting lasers are also discussed.(c) 2021 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

Automated summary

This review provides an overview of the recent advances in lanthanide doped upconversion materials for microlasers, including random lasers from photon scattering, whispering gallery mode (WGM)/Fabry-Perot (FP) cavity lasers, and photon lattice/plasmonic cavity modulated lasers. The current challenges and future directions of upconverting lasers are also discussed.