Highly Efficient Passively $Q$-switched Yb:YAl$_{3}$(BO$_{3}$)$_{4}$–Cr$^{4 +}$:YAG Laser End-Pumped by a High-Power Diode

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We report, for the first time to our knowledge, the passively <formula formulatype="inline"><tex>$Q$</tex></formula>-switched laser performance of the Yb:YAl<formula formulatype="inline"><tex>$_{3}$</tex></formula>(BO<formula formulatype="inline"><tex>$_{3}$</tex></formula>)<formula formulatype="inline"> <tex>$_{4}$</tex></formula> crystal operating at <formula formulatype="inline"> <tex>${\sim} {\hbox {1}}\ \mu$</tex></formula>m with a Cr<formula formulatype="inline"> <tex>$^{4+}$</tex></formula>:YAG crystal used as the saturable absorber. Employing a compact plano-concave resonator end pumped by a high-power diode, we obtained by using a 2 mm thick <formula formulatype="inline"><tex>$a$</tex></formula> -cut crystal a <formula formulatype="inline"><tex>$\sigma$</tex></formula>-polarized average output power of 4.15 W at 1041.3 nm with optical-to-optical and slope efficiencies as high as 48.3% and 59%, respectively. The <formula formulatype="inline"> <tex>$Q$</tex></formula>-switched output power generated with the <formula formulatype="inline"><tex>$c$</tex></formula>-cut crystal (2 mm thick) was lower due to the crystal inhomogeneity: 3.15 W with a slope efficiency of 48%. The highest pulse energy, shortest pulse duration and highest peak power achieved with the <formula formulatype="inline"><tex>$a$</tex></formula>- and <formula formulatype="inline"><tex>$c$</tex></formula>-cut crystals were found to be nearly identical, being 139 <formula formulatype="inline"><tex>$\mu$</tex> </formula>J, 18 ns, and 7.33 kW, respectively. </para>