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Self-Q-switched lasing was demonstrated for the first time around 2 μm in Thulium (Tm) doped CaF2 single-crystal fiber (SCF) using a compact linear cavity. Maximum average output power of 1.17 W was obtained under 2.38 W absorbed pump power, corresponding to the slope efficiency of up to 56.01%. Self-Q-switched laser with a 1.736 μs shortest pulse width at 48.80 kHz repetition rate was successfully realized. Besides, broad wavelength-tunable Tm:CaF2 SCF laser in 1859–2040 nm region was operated. These results show that the Tm:CaF2 SCF is a promising alternative for generating efficient micro diode-pumped pulsed lasers at 2 μm. [ABSTRACT FROM AUTHOR]

We demonstrated a passively Q-switched Er:Ca0.8Sr0.2F2 laser with indium tin oxide nanowire arrays as an optical modulator in the mid-infrared region. In the Q-switched regime, the maximum output power of 58 mW with a slope efficiency of 18.3% was acquired. Meanwhile, the minimum pulse duration and highest repetition rate of the stable pulse trains were 490 ns and 17.09 kHz, corresponding to single pulse energy of 3.4 μJ and peak power of 6.93 W, respectively. To the best of our knowledge it was the first time that indium tin oxide nanowire arrays were employed as a saturable absorber to make pulse lasers carried out at 2.8 μm. The experimental data show that indium tin oxide nanowire arrays can be employed as a competitive candidate for saturable absorber in the field of mid-infrared solid-state lasers. [ABSTRACT FROM AUTHOR]

We have demonstrated a 3-µm all-solid-state single-frequency laser with a stable center frequency and a switchable wavelength using the intra-cavity Fabry-Perot etalon method. Experimentally, the central wavelengths of the laser for the single-longitudinal mode are 2728 and 2794 nm, with maximum output powers of 268 and 440 mW, respectively. The corresponding single-longitudinal mode linewidths are 25 and 11 MHz. In particular, the central wavelengths of the single-longitudinal mode laser remain almost constant as the incident pump power increases. To the best of our knowledge, this study represents the first instance of using a laser diode to directly pump Er:CaF 2 block single crystals for single-frequency lasers in the 3 µm region. Additionally, it achieves the highest output power of a 3-µm all-solid-state single-longitudinal mode.

High-quality all-carbon nanostructure graphdiyne (GDY) saturable absorber was successfully fabricated and saturable absorption properties in the 2 μm region were characterized using a commercial mode-locked laser as a pulsed source. The fabricated GDY was first used as an optical switcher in a passively Q-switched Ho laser. Under absorbed pump power of 2.4 W, the maximum average output power and shortest pulse width were 443 mW and 1.38 µs, at a repetition rate of 29.72 kHz. The results suggest that GDY nanomaterial is a promising candidate as an optical modulator for generation of short pulses in Ho-doped lasers at 2.1 μm.