Fig. 5: Complex optical devices fabricated by using high-order lens-based lithography with laser ablation.

a Fabricated (left) and designed (right) binary-amplitude zone plates with a focal length of 200 μm at a working wavelength of 405 nm. Image of the fabricated zone plates is taken by using reflective microscopy, which reveals darkness in the etched region and brightness in the non-etched Cr film. b Designed and measured widths of zones in the FZP. c Simulated (solid curves) and measured (dots and forks) intensity profiles at the focal plane of the FZP. Inserts: 2-dimensional intensity profiles of the focal spots. d Microscope image of fabricated fork grating for generation of optical vortex. e Measured optical vortices at first-order diffraction of the fork grating under the illumination of a supercontinuum laser with the selected (using an acousto-optic modulator) wavelengths: 477 nm, 500 nm, 550 nm, 600 nm and 650 nm. f Fabricated “USTC” letters composed of gratings with different periods and orientations. The periods and orientations are labeled in the different groups of dashed rectangles. The inserts sketch the orientation of the gratings in each group. The grating periods are 1 μm, 2 μm, 3 μm 4 μm for the characters from the upper to the lower rows. g Observed images of the fabricated letters by rotating the sample that is illuminated by a white light. The letters appear at the designed angles, which confirms the validity of the fabricated orientations in the gratings. The color overlaying of the letters in each view angle is different, which is attributed to the dispersion of gratings with different periods. All the samples are fabricated on a 10-nm-thick Cr film at \(\Delta z=0\,{{\rm{\mu }}}{{\rm{m}}}\) with a pulse power of 0.2 mJ at a repetition rate of 25 Hz and an exposure time of 200 ms.