High-Power Orbital Angular Momentum Modes Obtained by Phase-Locking Lasers in a 1D Ring Array

We investigate the generation and propagation of high-power orbital angular momentum (OAM) modes by a phase-locking one-dimensional (1D) ring array of lasers. Such OAM modes are also referred to as discrete vortices. Phase locking enables the generation of high-power vortices, as several lasers are locked to generate a single high-power beam. The lasers are phase-locked in a desired phase configuration (OAM modes) by adding spatial Fourier filtering, through a specifically designed amplitude mask, inside a degenerate cavity. Unlike continuous vortices (Laguerre-Gaussian/Bessel beams), for a given system size and fixed inter-laser separation, the divergence of a discrete vortex does not depend on the orbital angular momentum (or topological charge). Further, we show that the discrete vortices also exhibit good self-healing properties against different kinds of obstructions in the waist plane (z = 0) as well as in the propagation plane (z > 0).