Direct generation of 523 nm orbital Poincaré mode from a diode-pumped Pr3+:LiYF4 laser with an off-axis optical needle pumping geometry

We demonstrate an ultra-compact (8 mm-long) green orbital Poincaré Pr 3+ :LiYF 4 (YLF) laser, in which the intracavity lasing modes are represented as eigenmodes on an equivalent orbital Poincaré sphere (eOPS). This is achieved through the simple application of an ‘optical-needle’ pumping geometry in conjunction with off-axis laser mode-manipulation. Optical vortices that are produced and mapped on north and south poles of the eOPS exhibit a maximum output power of 304 mW with a pump-to-laser-output slope efficiency of 12%. In addition, higher-order structured modes, including Ince Gaussian (IG), helical IG (HIG), Hermite-Laguerre Gaussian (HLG) and vortex lattices, can be directly generated from the laser cavity.