High efficiency Nd:YAG ceramic eye-safe laser operating at 1442.8 nm

Tin diselenide-based saturable absorbers for eye-safe pulse lasers

Eye-safe pulse lasers have attracted increasing attention due to their potential wide application in many fields. However, optical modulators with excellent nonlinear optical absorption properties in the range of 1.4-2.1 μm are still very scarce. In this study, tin diselenide (SnSe₂), a newly-developed 2D layered semiconductor material with facile processability and low cost, was investigated. The nonlinear optical response of SnSe₂ was investigated using the open aperture Z-scan method at 1500 and 1800 nm. Using SnSe₂ as the saturable absorber, a passive Q-switched solid-state laser was realized at 1.3 and 1.9 μm for the first time. This study proved SnSe₂ to be an effective optical modulating material for the eye-safe waveband.

High Power 1443.5 nm Laser with Nd:YAG Single Crystal Fiber

A high-power eye-safe 1443.5 nm laser was demonstrated with an Nd:YAG single crystal fiber (SCF) as the gain medium. For continuous wave (CW) operation, a maximum output power of 13.3 W was obtained under an absorbed pump power of 95.0 W, corresponding to an optical-to-optical conversion efficiency of 14.0%. For acousto-optically (AO) Q-switched regime, an output power of 1.95 W was obtained at a pulse repetition frequency (PRF) of 10 kHz. The pulse duration was 69.5 ns. The pulse energy and peak power were calculated to be 195 µJ and 2.81 kW, respectively.

First laser oscillation of diode-pumped Tm3+-doped LuScO3 mixed sesquioxide ceramic

Tm³⁺-doped LuScO₃ mixed sesquioxide ceramics were successfully fabricated by using a solid-state reactive sintering method. The absorption and emission spectra were measured at room temperature. Continuous-wave (CW) and passively Q-switched laser operation of Tm³⁺:LuScO₃ ceramic were investigated for the first time to our knowledge. A CW output power of 211 mW with slope efficiency of about 8.2% was obtained. With single-walled carbon nanotube (SWCNT) as saturable absorber, a maximum average output power of 32 mW was achieved. The shortest pulse width was 0.59 μs at pulse repetition rate of 34.72 kHz.

Gold nanobipyramid Q-switched Nd:LGGG eye-safe laser operating at 1423.4 nm

The performance of a laser-diode-pumped passively Q-switched Nd:LGGG laser at 1423.2 nm with gold nanobipyramids (Au-NBPs) as a saturable absorber was demonstrated. An average output power of 125 mW was obtained at a pump power of 12.2 W, corresponding to an optical-to-optical conversion efficiency of 1.36% and a slope efficiency of 1.78%. A minimum pulse width of 514 ns at a pulse repetition rate of 98.6 kHz was obtained at a pump power of 12.2 W. To the best of our knowledge, this is the first report focusing on the application of Au-NBPs as a saturable absorber for pulse laser operation in the eye-safe region.

Stable high-power Er:YAG ceramic single-frequency laser at 1645 nm

A stable high-power single-frequency laser at 1645 nm from a monolithic Er:YAG ceramic nonplanar ring oscillator (NPRO) was demonstrated. 10.7 W single-frequency laser output was obtained with a slope efficiency of 61.2% and an optical efficiency of 52.1% with respect to incident pump power. The laser always stably operated in single-frequency mode with the pump power increasing from threshold to maximum pump power. When the crystal's set temperature changed from 17.2°C to 26.6°C, the Er:YAG ceramic NPRO had stable single-frequency laser output, and the widest continuous tuning range without mode-hoping was 4.5 GHz. The linewidth of the single-frequency laser was 5.75 kHz. The beam quality M² factors were 1.23 and 1.24 in x and y directions, respectively.

Passively Q-switched Nd:YAG ceramic laser with V(3+):YAG saturable absorber at 1357 nm

1357 nm single-wavelength continuous-wave and passively V(3+):YAGQ-switched Nd:YAG ceramic crystal lasers have been experimentally demonstrated for the first time to our knowledge. The output power of the continuous-wave laser was as high as 2.4 W under the incident pump power of 14.8 W. The corresponding optical to optical efficiency was about 16.2% and the slope efficiency was about 18.6%. The Q-switched laser remained single-wavelength output with a maximum average output power of 628 mW at the incident pump power of 12.4 W. The corresponding pulse width was 21 ns and the repetition frequency was 15 kHz.

Efficient eye-safe neodymium doped composite yttrium gallium garnet crystal laser

We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 μm with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 μm was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 μJ, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers.

Luminescence of Nd3+ ions under excitation of CdSe quantum dots in a glass system: energy transfer

We report rare evidence of energy transfer from CdSe quantum dots (QDs) to Nd3+ ions in a SNAB glass system using absorption electronic transitions of ion as a nonresonant excitation source. However, the luminescence band was observed at 880 nm (4F3/2→4I9/2 transition) under 409 nm excitation only when Nd3+ ions were embedded in the SNAB glass system with CdSe QDs. This happened because the Nd3+ ions absorbed the photons emitted by CdSe QDs with 409 nm excitation. Band overlap of the QD luminescence band and the ion optical absorption bands caused photon absorption and produced valleys in the QD luminescence spectrum. This overlap contributed to reduction in the lifetime 4F3/2 state.