Passive Q-switching of an Er, Yb:glass laser with Co:Mg(Al,Ga)_2O_4-based glass-ceramics

Abstract

Transparent glass-ceramics (GCs) containing Co:Mg(Al,Ga)₂O₄ nanocrystals (mean diameter of 7-9 nm) are synthesized by heat treatments at 850-950°C from magnesium aluminosilicate glass nucleated by TiO₂ and doped with Ga₂O₃ and CoO. The GCs exhibit a broadband A₂4(F4)→T₁4(F4) absorption due to the Co²⁺ ions, low saturation fluence (∼0.5 J/cm²), fast recovery time of initial absorption (∼300 ns), and high laser damage threshold (∼20 J/cm²). They are used for passive Q-switching of a diode side-pumped Er,Yb:glass laser generating 3.1 mJ/20 ns pulses (peak power, 155 kW) at 1535 nm with a TEM₀₀ output mode. The Q-switching performance of the Co:Mg(Al,Ga)₂O₄-based GCs is compared with that for various Co²⁺-doped GCs and Co:MgAl₂O₄ single crystal. The prepared GCs are promising for further applications in passively Q-switched Er:YAG and other Er crystalline (or ceramic) lasers.

Saturable absorption properties at 1.54 µm of Cr2+:ZnS prepared by thermal diffusion at hot isostatic pressing

“…However, the GSA crosssections for Co 2+ ions in spinel-type crystals are lower than those for Cr 2+ ions in zinc chalcogenides [19]. Moreover, the Co 2+ ions exhibit ESA and their near-IR absorption (related to the 4 A 2 ( 4 F) → 4 T 1 ( 4 F) transition) does not typically extend beyond 1.6 µm, unless a special spinel composition is selected [20]. Moreover, thermal conductivity of ZnS is higher than that of spinel.…”

Local Chemistry Engineering in Doped Photonic Glass for Optical Pulse Generation

“…Importantly, this is a good complement for Co-doped photonic glass, allowing the wavelength of the pulse to completely cover frequency range of 800-1700 nm. [50] By stark contrast to the conventional optical modulation component which is incompatible with the fiber device, the newly developed nanostructured photonic glass and fiber can be easily connected to the active fiber by thermal fusion. This property indicates its promising application in all-fiber photonic system.…”

Microstructure, doping and optical properties of Co2+:ZnAl2O4 transparent ceramics for saturable absorbers: Effect of the ZnF2 sintering additive

“…This absorption spectrally matches the emission of eye-safe erbium lasers. As a result, Co:MgAl2O4 based crystalline materials have been recognized as SAs of pulsed erbium lasers [21][22][23][24] with applications in range-finding, remote sensing (LIDAR), medicine, etc.…”