Spatial-temporal manipulations of visible nanosecond sub-pulse sequences in an actively Q-switched Pr:YLF laser

TL;DR

This paper demonstrates the active control of pulse sequences and high-order vortex beams in a visible Q-switched laser, enabling reconfigurable sub-pulse patterns and complex beam modes for advanced laser applications.

Contribution

It introduces a novel method for simultaneous manipulation of pulse sequences and vortex beam modes in a visible laser, combining acoustic-optic modulation and off-axis pumping techniques.

Findings

Generated up to 4 controllable sub-pulses with adjustable intensity.

Produced high-quality vortex beams up to 30th order Laguerre-Gaussian modes.

Achieved the most flexible active control over both temporal and transverse mode distributions.

Abstract

Pulsed visible lasers either by Q-switching or mode locking have been attracting intense attentions both in solid-state laser and fiber laser. Here, we report on the simultaneous manipulation of reconfigurable sub-pulse sequences and customizable high-order vortex beams in an actively Q-switched visible laser. On the one hand, pulse sequences with up to 4 sub-pulses could be generated and fully controlled by means of an acoustic-optic modulator driven by an arbitrary waveform generator. Both pulse number and pulse intensity can be manipulated through the programmable step-signal, which is also theoretically simulated through the rate equations. On the other hand, assisted by the off-axis pumping technique and the astigmatic mode conversion, the laser cavity could emit high-quality vortex beams carrying Laguerre-Gaussian modes up to 30th order. To the best of our knowledge, this is the most flexible active manipulations not only on the intensity distribution of the transverse modes but also on the temporal distribution of the pulse sequences in a visible laser. The versatile manipulating techniques in this work could be immediately implemented into all other solid-state lasers to obtain sub-pulse vortex beams, which may provide enhanced functionality and flexibility for a large range of laser systems.