“…Frequently, in these systems, Yb 3 þ ions are incorporated to absorb IR (976-980 nm) radiation and transfer part of their energy by energy transfer (ET) and cooperative sensitization processes to lanthanide ions such as Ho 3 þ , Tb 3 þ , Pr 3 þ , Tm 3 þ , and Er 3 þ to obtain blue, green and red up-conversion (UC) emissions [4][5][6][7]. In particular, Er 3 þ ion has inter-4f level transitions in the near infrared region (NIR), which match with the 1532, 980 and 810 nm diode laser radiations [8][9][10].…”