SESAM-based mode-locked vortex Ti:sapphire laser using spot-defect spatial filter for intra-cavity mode selection

Abstract

Abstract In virtue of the significance of ultrashort vortex pulses, a mode-locked LG01-mode vortex Ti:sapphire laser is first realized. In the study, an intra-cavity spot-defect spatial filter was used to suppress the TEM00 mode’s oscillation and a semiconductor saturable absorber mirror was used as the mode-locked device. As a result, the mode-locked laser emitted LG01-mode vortex pulses of 186 ps at 804.4 nm with a repetition rate of 78.95 MHz and a maximum average output power of 176 mW. The phase of the LG01 mode was measured by a Mach–Zehnder interferometer and both right- and left-handed helical wavefronts were obtained.