Orbital Angular Moment Density of Beam Given as a Superposition of Hermite-Laguerre-Gauss Functions

Orbital angular moment (OAM) is an important global parameter of beam which can be found from its second order moments. Nevertheless often, for example for the description of the interaction of light with microparticles, the knowledge of the OAM density is required. Hermite-Laguerre-Gauss (HLG) modes which form a complete orthonormal basis are frequently used for beam design. In this contribution we derive the expression for the OAM density of beam given as a superposition of the HLG modes. The result is useful for the generation and charac- terization of stable, spiral, rotating beams and their application for microparticle manipulation.