Direct generation of instantaneous 776 nm and 780 nm vortex lasers in alexandrite

Abstract

Optical vortices, beams with spiral wavefronts and screw phase dislocations, have been attracting increasing interest in various fields. Vortex lasers emitting at 776 nm and 780 nm have significant potential for applications in atomic cooling and heating. However, their development is constrained by the inherent limitations and suboptimal efficiencies associated with current generation techniques. To the best of our knowledge, this work represents the first demonstration of a simple and efficient approach for generating transient pulsed vortex lasers at these wavelengths, utilizing a resonator that incorporates defect mirrors and an alexandrite crystal. The pulsed lasers were obtained using Cu₃Se₂ saturable absorbers, resulting in repetition rates and pulse widths of 48 kHz and 747 ns for the 776 nm laser, and 45 kHz and 802 ns for the 780 nm laser, respectively. This method provides a promising laser source for applications in atomic physics, offering a robust and effective approach for generating 776 nm and 780 nm vortex lasers.