Fig. 1. Intensity distribution at focal spot of double-helix beams superposed by five modes along lines with different slopes in LG modal plane

Fig. 2. Intensity distribution at focal spot of double-helix beams with different waist widths

Fig. 3. Flowchart of focal intensity optimization based on vector diffraction theory

Fig. 4. Optimization results. (a)(d) Phase masks; (b)(e) intensity distributions at focal spot; (c)(f) SEM images of polymerized structure with single-exposure; (upper) before optimization; (down) after optimization

Fig. 5. Schematic diagram of experimental setup for two-photon polymerization with single exposure

Fig. 6. SEM images of polymerized double-helix microstructures. (a) Double-helix microstructure array; (b) top and (c) side view of single double-helix microstructure