“…KYb(WO4)2, can also be realized [104]. Many reports had shown that concentration dependent lifetime quenching on these high Yb 3+ concentration crystals is very limited [65,106,107]. In addition, the KRE(WO4)2:Yb 3+ has absorption band at ~932 nm and ~981 nm, hence permitting the use of high brightness, high wall-plug efficiency InGaAs pump lasers [75].…”