Sum frequency generation with two orbital angular momentum carrying laser beams

Abstract

The frequency sum of two laser beams carrying orbital angular momentum (OAM) in quasi-phase matching crystals was reported. The situations in which one beam carried OAM, the other was in Gaussian mode, and both beams carried OAM were studied in detail. The sum of the two beams’ OAM was demonstrated in the conversion process, which verified OAM conservation in the sum frequency generation process. We give an analytical expression for the frequency conversion of two OAM-carrying beams; the experimental results are well matched with the theoretical simulations. The methods shown here provide an effective way for OAM light generation. Our study is very promising in constructing hybrid OAM-based optical communication networks and all-optical spatial mode switching.