Interaction of Excited Cr3+ Ions in Laser Crystals

Q-switching of a Tm,Ho:KLu(WO4)2microchip laser by a graphene-based saturable absorber

“…Antipenko studied Tm ↔ Ho ET, sensitized stimulated emission of Ho 3+ ions and the thermal physics of Tm,Ho:BaEr 2 F 8 [19][20][21] and Tm,Ho,Cr:YAG [22,23] crystals. A detailed discussion of the mechanisms of the above-mentioned ET, and an interpretation of the luminescence decay curves for Tm 3+ and Ho 3+ ions, was presented for Tm,Ho,Cr-codoped YSGG and GSAG garnets by Shcherbakov and co-authors [24][25][26]. ET and, in particular, upper state lifetimes for (Tm 3+ , Ho 3+ ) coupled systems were investigated by Huber and co-authors using Tm,Ho:YAG crystals [27][28][29].…”

Heat, fluorescence, and stimulated-emission power densities and fractions in Nd:YAG

“…As we will see later in this paper, stimulated emission from a laser beam or from ASE can reduce the heating produced in Nd:YAG. 6) Upconversion: Upconversion has been identified to be important in some solid-state materials such as Cr:LiSAF [27], [28]. It has been conjectured that the effect is partially responsible for the increase in heat load observed in diode-pumped Nd:YAG amplifiers when stimulated emission is absent [14].…”

“…Finally, we must also account for the heating associated with stimulated-emission, or which can be written (26) We can sum all heating contributions to obtain the total heat power density given by (27) The fluorescence power densities can also be easily obtained, and are given by (28) We can sum (28) over the four manifolds to yield the total fluorescence density given by (29) If stimulated emission is present, the amount of fluorescence power decreases since from (15) the CW inversion density decreases. We can also find the stimulated emission or laser power density as…”

Upconversion from the 4I13/2 and 4I11/2 levels in Er:YAG

“…1) favors a large variety of other energy transfer processes, such as ETU from 4 I 11/2 [11], cross-relaxation from 4 S 3/2 [12,13] and cross-relaxation from 4 I 9/2 [14,15]. As a result of these energy transfer processes, the population inversion for high erbium concentrations and high pump levels depends no more on the lifetimes of the laser levels, but on the ratio of the ETU parameters (more precisely, on the square root of this ratio) [16][17][18].…”