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We demonstrated an LG 01 -mode vortex Ti:Sapphire laser by utilizing an intracavity spot defect for spatial filtering. At the 140-μm diameter of spot defect, the power of vortex laser output reached 135 mW, and the slope efficiency of laser was 17.7%. The effects of the sizes of spot defects on the transverse laser modes and laser powers were also discussed. [ABSTRACT FROM AUTHOR]

• Laser power expansion is mainly realized by power amplifier. • The process of power amplification is usually accompanied by some unfavorable factors. • Effective thermal management is the main way to eliminate adverse factors. • Mode matching is more conducive to power amplification. A rotary Nd:YAG disk amplifier with a doughnut shape pump beam for azimuthally polarized laser maintaining high amplification efficiency and high-quality amplification is demonstrated. Using a 2 mm thick disk as an amplifier, the amplification of small signals with different power under different pump power is investigated. Under the maximum absorbed pump power of 34.7 W, after a single-pass the seed power of 1 W and 5 W can be amplified by the amplification factor about 3.3 and 2, respectively, and the beam quality and the polarization purity remain well. [ABSTRACT FROM AUTHOR]

Abstract: The transient temperature profile in CW- and end-pumped passively Q-switched (PQS) microchip laser is investigated qualitatively by treating the population inversion (thereby the thermal load) as the sawtooth function of the time. The numerical results reveal not only the dynamics of thermal buildup, but also the dependence of the quasi-steady-state temperature rise and the repetitively oscillatory amplitude on the incident pump power and the pulse repetition rate of PQS laser. The abruptly ascending branch of the repetitive temperature oscillation is synchronized with the pulsing stage of PQS laser. As the result, the abrupt temperature transition during the pulsing stage would introduce the fluctuation into the PQS pulse parameters (pulse energy, pulse width, and peak power) via temperature-dependent stimulated emission and thermal lensing effect. [Copyright &y& Elsevier]

Cylindrical vector-polarized vortex pulses from a passively Q-switched laser are demonstrated. Pump radiation reshaped into a size-controlled annular profile via circular Dammann grating produces an efficient excitation of the LG01 mode. The YAG / Nd : YAG / Cr4 + : YAG composite crystal structure is found to reduce the Q-switching threshold and significantly suppress thermal damage, thus allowing ability to obtain a passively Q-switched pulse. The threshold pumping power is found to be 4.35 W, with a slope efficiency of 23.1%. A maximum peak power of 3.24 kW, maximum pulse energy of 53.46 μJ, pulse width of 17.5 ns, and repetition rate of 2.695 kHz are obtained. Furthermore, a radially polarized output with a polarization degree of 88.9% is confirmed. Finally, mode and polarization tuning are also discussed. [ABSTRACT FROM AUTHOR]