Three-dimensional nanoscale vortex line visualization and chiral nanostructure fabrication of tightly focused multi-vortex beams via direct laser writing

Optical singularity is pivotal in nature and has attracted wide interest from many disciplines nowadays,including optical communication,quantum optics,and biomedical imaging.Visualizing vortex lines formed by phase singularities and fabricating chiral nanostructures using the evolution of vortex lines are of great significance.In this paper,we introduce a promising method based on two-photon polymerization direct laser writing(2PP-DLW)to record the morphology of vortex lines generated by tightly focused multi-vortex beams(MVBs)at the nanoscale.Due to Gouy phase,the singularities of the MVBs rotate around the optical axis and move towards each other when approaching the focal plane.The propagation dynamics of vortex lines are recorded by 2PP-DLW,which explicitly exhibits the evolution of the phase singularities.Additionally,the MVBs are employed to fabricate stable three-dimensional chiral nanostructures due to the spiral-forward property of the vortex line.Because of the obvious chiral features of the manufactured nanostructures,a strong vortical dichroism is observed when excited by the light carrying orbital angular momentum.A number of applications can be envisioned with these chiral nanostructures,such as optical sensing,chiral separation,and information storage.

Method for active spatial alignment and stabilization of laser beams in multi-beam systems

We propose a new method for the development of multi-beam systems for the spatial alignment and stability of beams based on the error separation technique.This method avoids alignment errors caused by coupling effect of piezoelectric devices,inaccurate correction calculations,and detection mode of the angular deviation.According to the results by external detectors,the error value of spatial alignment and the root mean square[RMS]of deviations under control during 1 h can be equivalent to approximately 0.87 and 1.06 nm at the sample plane under an oil immersion lens[focal length f=2 mm].The RMS of deviations is less than one-third of those currently reported for multi-beam systems;therefore,higher alignment and stability accuracy can be achieved with our proposed method.

Direct laser writing breaking diffraction barrier based on two-focus parallel peripheral photoinhibition lithography(Erratum)

In section 3.2,a reference(Ref.33)was missing in the first sentence.It was already listed in the References list and correctly cited in another portion of the text.Section 3.2,the second sentence incorrectly referred to the"pattern in Fig.2";the pattern was specific to Fig.S6 in the Supplemental Material.

Direct laser writing breaking diffraction barrier based on two-focus parallel peripheralphotoinhibition lithography

Direct laser writing(DLW)enables arbitrary three-dimensional nanofabrication.However,the diffraction limit poses a major obstacle for realizing nanometer-scale features.Furthermore,it is challenging to improve the fabrication efficiency using the currently prevalent single-focal-spot systems,which cannot perform high-throughput lithography.To overcome these challenges,a parallel peripheral-photoinhibition lithography system with a sub-40-nm two-dimensional feature size and a sub-20-nm suspended line width was developed in our study,based on two-photon polymerization DLW.The lithography efficiency of the developed system is twice that of conventional systems for both uniform and complex structures.The proposed system facilitates the realization of portable DLW with a higher resolution and throughput.