Abstract

A new device concept - the reflective spiral phase converter - is presented. The converter can be used for generation of ultrashort optical vortices and takes advantage of spiral phase plate to impose the vortex phase, and of a multilayer structure to compensate the dispersion acquired by incident pulse. We use (3+1)D numerical analysis of the spatio-spectro-temporal properties of ultrashort vortex pulses to quantify the effects of chromatic dispersion and propagation geometry, and characterize the efficiency of the device by checking the purity of the modes generated. Results of case studies in UV-VIS-NIR spectral ranges are presented. The proposed device allows to surpass the limitations of bandwidth from standard SPPs while keeping the pulse width and shape as undistorted as possible so it can widely be used for generation of ultrashort optical vortices.