CW and Q-switched operations of a Tm³⁺:YAP laser at 1892–1994 nm In-band fiber-laser pumped at 1670 nm

Abstract

Tm3+:YAP lasers in-band fiber-laser pumped at 1670 nm with a linear or L-shaped cavity were studied in CW, actively and passively Q-switched regimes. High-efficiency CW and repetitively-pulsed operations were registered at three spectral regions: 1987–1994 nm, 1935–1941 nm and 1892–1897 nm. The transition between these three spectral regions was achieved by controlling the pump power and the output mirror in a laser cavity. The highest CW output power that was achieved without degrading the beam quality was 12.2 W at the 52% slope efficiency with respect to the incident pump. Acousto-optically Q-switched operation with the average power of 9.8 W at the 20 kHz pulse repetition rate (PRR) and 6 W at 3 kHz PRR was achieved, the pulse energy was scaled up to 2.7 mJ at 0.5 kHz PRR. The passive Q-switch operation at 1935–1938 nm was obtained using a Cr2+:ZnSe saturable absorber; the pulse energy reached 150 µJ at the 20 kHz PRR

High Repetition-Rate 2.3–2.7 µm Acousto-Optically Tuned Narrow-Line Laser System Comprising Two Master Oscillators and Power Amplifiers Based on Polycrystalline Cr2+:ZnSe with the 2.1 µm Ho3+:YAG Pulsed Pumping

“…The focal length of the steady-state thermal lens fT was estimated by the following expression [37,38]: where Pin is the average incident pump power with a Gaussian beam radius of ap. The other parameters of the crystal, pump beam, and laser cavity (including the TeO2 AOTF) are shown in Table 1.…”

High-Repetition-Rate 2.3–2.7 µm Acousto-Optically Tuned Narrow-Line Laser System Comprising Two Master Oscillators and Power Amplifiers Based on Polycrystalline Cr2+:ZnSe with the 2.1 µm Ho3+:YAG Pulsed Pumping

“…The focal length of the steady-state thermal lens f T was estimated using the following expression [48,49]:…”

High efficiency in-band pumped Tm- and Ho-doped 2-μm solid-state lasers

“…The in-band pumping of the 3 H6-3 F4 Tm 3+ -ion transition enables the high-efficiency and high-power operation of Tm 3+ -doped lasers at 1900-2100 nm with a low quantum defect [12][13][14][15][22][23][24][25][26][27]. Direct excitation of Tm 3+ ions into the upper laser level 3 F4 results in the reduced thermal load and high laser efficiency compared to the diode pumping into 3 H4 level with the cross relaxation ( 3 H4, 3 H6) → ( 3 F4, 3 F4).…”

“…In this paper an overview of our recent achievements in the 2-μm solid-state lasers based on Tm 3+doped ceramics (Lu2O3 or Y2O3) or YAP crystals in-band pumped by a fiber laser at 1670 nm is reported [12][13][14][15]. Different operation modes (CW, actively or passively Q-switch) of our lasers are described.…”