ABSTRACT
Rare earth doped/codoped upconversion nanoparticles facilitate anti-Stokes emission with different pump power and also show nonlinear optical properties with infrared excitation. Interesting properties such as anti-Stokes shifts, long lifetimes and sharp emissions have attracted researchers’attention in diverse field applications. In this chapter, we describe the fundamental concepts of fluoride-based host matrices for upconversion emission. The fluoride-based hosts have been chosen for different applications of imaging systems due to their low phonon frequency and composition stability. In particular, we emphasize the advanced synthesis features and bio-imaging applications of fluoride-based host materials for infrared excitations.
