Energy transfer processes in ${Er}^{3 +}$ -doped and ${Er}^{3 +} {, P r}^{3 +}$ -codoped ZBLAN glasses

We present a detailed characterization of energy transfer processes in

{Er}^{3 +}

-doped and

{Er}^{3 +} {, P r}^{3 +}

-codoped ZBLAN bulk glasses. For several

{Er}^{3 +}

(0.25–8.75 mol%) and

\Pr^{3 +}

(0.25–1.55 mol%) concentrations, we investigate energy transfer upconversion (ETU) and cross relaxation in

{Er}^{3 +}

as well as energy transfer (ET) from

{Er}^{3 +}

to the

\Pr^{3 +}

codopant. The measured parameters of ETU from the

{Er}^{3 +}^{4} I_{13 / 2}

and

^{4} I_{11 / 2}

levels are comparable to those of

{LiYF}_{4} {: E r}^{3 +} .

ETU from

^{4} I_{13 / 2},

in particular, possesses a factor of 3 larger probability than ETU from

^{4} I_{11 / 2} .

The parameters of ET from the

{Er}^{3 +}^{4} I_{13 / 2}

and

^{4} I_{11 / 2}

levels to the

\Pr^{3 +}

codopant are larger than the corresponding ETU parameters. ET effectively quenches the

^{4} I_{13 / 2}

intrinsic lifetime of 9 ms down to 20 μs for the highest

{Er}^{3 +}

and

\Pr^{3 +}

concentrations investigated, and is more efficient than ET from

^{4} I_{11 / 2},

because the corresponding absorption transition in

\Pr^{3 +}

has a large oscillator strength and back transfer is inhibited by fast multiphonon relaxation from the corresponding

\Pr^{3 +}

level. In both cases, the ET parameters depend on

{Er}^{3 +}

concentration in a similar way as the ETU parameters but depend only weakly on

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Energy transfer processes in Er3+-doped and Er3+,Pr3+-codoped ZBLAN glasses