Experimental investigation of optical vortex generated by volume holography

Complicated optical vortices can be generated by holography and their topological structures could be controlled easily, but the obtained diffraction efficiencies are usually low. It was investigated that optical vortex was stored and reconstructed in LiNbO₃:Fe crystal by volume holography. The results exhibit that diffraction efficiency of vortex beam was achieved at 26.7% in a crystal just with a thickness of 0.6 mm, and the quality of reconstructed vortex was almost identical to that of original one. Furthermore, by employing Kogelnik's coupled-wave theory, the results of numerical computations according to the experimental parameters show that diffraction efficiency of vortex beam could attain to 100% as the thickness of crystal reached 1.23 mm with the same crystal and the same exposure parameters.