Generating high-peak-power structured lights in selectively pumped passivelyQ-switched lasers with astigmatic mode transformations

Abstract

Various high-order Hermite-Gaussian (HG) modes with high repetition rates and high peak powers are systematically generated by designing the cavity configuration to satisfy the criterion of the passive Q-switching. For the HG m,0 modes with the order m = 1-9, the pulse repetition rate can exceed 100 kHz with peak power higher than 0.3 kW. For the HG m,m modes with the order m = 1-10, the pulse repetition rate can be up to 37 kHz with peak power higher than 0.35 kW. Furthermore, the high-order HG beams is transformed by using an astigmatic mode converter to generate various structured lights with optical vortices. Experimental patterns of the transformed high-order HG beams in the propagation are theoretically analyzed and the phase structures are numerically manifested.

Optical vortices 30 years on: OAM manipulation from topological charge to multiple singularities

“…In 2016, Zhao et al 179 controlled the pump position in an Er:YAG acoustic-optic Q-switched laser, generating a nearly 1-mJ and 50-ns pulsed VB. In 2017, Chen’s group 180 designed a nanosecond vortex laser system employing a compact Nd:YVO 4 /Cr 4+ :YAG passively Q-switched laser with an external AMC. In 2018, He et al 181 presented a Cr,Nd:YAG self-Q-switched microchip laser to directly generate low-threshold nanosecond high-repetition-rate vortex pulses without an AMC, where the chirality was controlled by a tilted output mirror.…”

“…With the development of high-power and large-energy VBs 92,180,251 , the peak power can exceed the threshold of various nonlinear effects, providing conditions to explore novel nonlinear conversion phenomena related to OAM 48,49,251 . Conventionally, the development of nonlinear optics was based mainly on the scattering that obeys momentum conservation (Rayleigh scattering, Brillouin scattering, Raman scattering, etc.…”

Thermal aberrations and structured light I: analytical model for structured pumps and probes

“…Amongst these are examples of using structured pump light [70,71] to control the fundamental mode of the laser, thus potentially imparting a structured thermal gradient in the gain medium. In addition, there has been a move more recently towards higher powers with such structured light, either directly from the source [72][73][74][75][76][77] or by subsequent amplification [78][79][80][81][82][83]. Yet the impact of the structure of the light on the thermally induced effects has hitherto been neglected, as has the impact of the thermally induced phases and polarisation effects on the structure of the beam itself.…”