Efficient generation of optical bottle quasi-Bessel beams using a two-step blazed axicon grating

A two-step blazed axicon grating (TBAG) to generate an optical bottle quasi-Bessel beam (QBB) with high optical efficiency and uniform intensity modulation is reported. To overcome the limitations of optical bottle QBBs generated by conventional binary axicons, an optimized TBAG structure is designed to enable interference only between first-order diffracted beams with maximized diffraction efficiency. The optimized phase profile for the TBAG is applied in an optical imaging system incorporating a spatial light modulator, producing a high-quality optical bottle QBB over a long propagation length. The experimental results are in excellent agreement with the theoretical predictions, including the analytical calculation of the modulation period. The benefits of the TBAG configuration and its prospects in applications are discussed.