title: Passive Q-switching of microchip lasers based on Ho:YAG ceramics.
abstract: A Ho:YAG ceramic microchip laser pumped by a Tm fiber laser at 1910 nm is passively Q-switched by single- and multi-layer graphene, single-walled carbon nanotubes (SWCNTs), and Cr2+:ZnSe saturable absorbers (SAs). Employing SWCNTs, this laser generated an average power of 810 mW at 2090 nm with a slope efficiency of 68% and continuous wave to Q-switching conversion efficiency of 70%. The shortest pulse duration was 85 ns at a repetition rate of 165 kHz, and the pulse energy reached 4.9 μJ. The laser performance and pulse stability were superior compared to graphene SAs even for a different number of graphene layers (n=1 to 4). A model for the description of the Ho:YAG laser Q-switched by carbon nanostructures is presented. This modeling allowed us to estimate the saturation intensity for multi-layered graphene and SWCNT SAs to be 1.2±0.2 and 7±1  MW/cm2, respectively. When using Cr2+:ZnSe, the Ho:YAG microchip laser generated 11 ns/25 μJ pulses at a repetition rate of 14.8 kHz.
authors.forename: R
authors.initials: R
authors.lastname: Lan
authors.forename: P
authors.initials: P
authors.lastname: Loiko
authors.forename: X
authors.initials: X
authors.lastname: Mateos
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: Y
authors.initials: Y
authors.lastname: Pan
authors.forename: S Y
authors.initials: SY
authors.lastname: Choi
authors.forename: M H
authors.initials: MH
authors.lastname: Kim
authors.forename: F
authors.initials: F
authors.lastname: Rotermund
authors.forename: A
authors.initials: A
authors.lastname: Yasukevich
authors.forename: K
authors.initials: K
authors.lastname: Yumashev
authors.forename: U
authors.initials: U
authors.lastname: Griebner
authors.forename: V
authors.initials: V
authors.lastname: Petrov