High Power Laser Science and Engineering, Volume. 13, Issue 4, 04000e51(2025)
Cross-relaxation and temporal dynamics of lasing at 2 μm in thulium-doped ceramic material
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![Scheme of the energy levels used to model the laser dynamics, drawn following the nomenclature used in Ref. [17].](/Images/icon/loading.gif){kind=icon}
Fig. 1. Scheme of the energy levels used to model the laser dynamics, drawn following the nomenclature used in Ref. [17].
Fig. 2. Measured absorption spectrum of the ceramic sample used in this work.
Fig. 3. Scheme (not to scale) of the experimental apparatus: the achromatic doublets (ADs) are used to focus the pump beam from the optical fiber to the sample; the cavity is made up of three mirrors (see text); the dichroic entry mirror (EM) and the spherical mirror (SM) feature a high-reflectivity (HR) coating for approximately 
radiation and an anti-reflectivity (AR) coating for the pump wavelength. A 90% or 97% reflectivity output coupler mirror (OM) is used throughout the measurement. Both the pump and the laser beams are monitored in terms of power and spectrum with photodiodes, power meters and spectrometers. In the inset, the laser spot is captured at a distance of 
from the output coupler mirror with a Dataray WinCamD camera.
Fig. 4. Laser spectra for the two 90% and 97% reflectivity output coupler mirrors. With the 97% reflectivity we observe a change in the emission spectra as a function of the cavity losses due to its alignment.
Fig. 5. Pump laser power transmitted as a function of the incident pump laser power for the two different working temperatures of 13°C and 
. Straight lines are the results of a best fit calculation that we use to obtain the pump absorption ratio 
in
Fig. 6. Laser power as a function of the effective absorbed pump power for the two working temperatures of 13°C and 
; the straight lines are the result of a best fit calculation that provides both the laser threshold power and the slope efficiency.
Fig. 7. Experimental and theoretical laser power as a function of Peff. The dashed line is a linear fit of the data, while the solid line is obtained with the model in 
is tailored to 1.3% for the model to match the data.
Fig. 8. Experimental and theoretical laser power as a function of time obtained for pump pulse width of 
in the top panel and 
in the bottom panel.
Table 1. Simulation parameters.
View tableView in ArticleTable 1. Simulation parameters.
Symbol Value ${R}_1$ 0.97 ${R}_2$ 0.999 $L$ 0.013 ${T}_{\mathrm{R}}$ 0.40 ns ${\sigma}_{\mathrm{a}}$ $3.0\times {10}^{-25}\;{\mathrm{m}}^2$ ${\sigma}_{\mathrm{e}}$ $8.3\times {10}^{-26}\;{\mathrm{m}}^2$ ${\sigma}_{\mathrm{aL}}$ $8.4\times {10}^{-27}\;{\mathrm{m}}^2$ ${\sigma}_{\mathrm{eL}}$ $4.2\times {10}^{-25}\;{\mathrm{m}}^2$ ${w}_0$ $145\;\mu \mathrm{m}$ $\varOmega /4\pi$ 0.0029
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Alessandro Fregosi, Fernando Brandi, Luca Labate, Federica Baffigi, Gianluca Cellamare, Mohamed Ezzat, Daniele Palla, Guido Toci, Alex Whitehead, Leonida A. Gizzi. Cross-relaxation and temporal dynamics of lasing at 2 μm in thulium-doped ceramic material[J]. High Power Laser Science and Engineering, 2025, 13(4): 04000e51
Paper Information
Category: Research Articles
Received: Nov. 25, 2024
Accepted: Apr. 17, 2025
Published Online: Aug. 12, 2025
The Author Email: Alessandro Fregosi (alessandro.fregosi@ino.cnr.it)
CSTR:32185.14.hpl.2025.37
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