Direct Generation of a Laguerre-Gaussian-Mode Optical Vortex Beam in a Single-Frequency Nd:YVO4 Unidirectional Ring Laser

Abstract

A single-frequency, unidirectional ring laser with a first order Laguerre-Gaussian (LG(01)) mode output end-pumped by using a ring-shaped pump beam is reported. This approach has been applied to a diode-pumped Nd:YVO4 laser in a traveling wave resonator configuration yielding 2.1 W and 1.5 W of single-frequency LG(01) mode outputs with helical wavefronts of left- and right-handedness, respectively. Moreover, we show that its wavefront helicity can be switched by changing the lasing direction and frequency. The selection mechanism of the wavefront helicity and the prospects of this approach are discussed.