Beams with optical vortices are widely used in various fields, including optical communication, optical manipulation and trapping, and, especially in recent years, in the processing of nanoscale structures. However, circular vortex beams are difficult to use for the processing of chiral micro and nanostructures. This paper introduces a multiramp helical–conical beam that can produce a three-dimensional spiral light field in a tightly focused system. Using this spiral light beam and the two-photon direct writing technique, micro–nano structures with chiral characteristics in space can be directly written under a single exposure. The fabrication efficiency is more than 20 times higher than the conventional point-by-point writing strategy. The tightly focused properties of the light field were utilized to analyze the field-dependent properties of the micro–nano structure, such as the number of multiramp mixed screw-edge dislocations. Our results enrich the means of two-photon polymerization technology and provide a simple and stable way for the micromachining of chiral microstructures, which may have a wide range of applications in optical tweezers, optical communications, and metasurfaces.

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.

In the process of urbanization, energy consumption has significant effect on carbon emissions. The aim of this paper is to analyze the impact of urbanization on carbon emissions for different income levels across 29 provinces of China during 1995-2015. The improved STIRPAT model provides the theoretical foundation for this research. Then, the threshold analysis was used to assess the effect of urbanization on carbon emissions. On the basis of the average annual income, two threshold points that divide the whole sample into three groups were identified, namely, 1) an average annual income of 7400 RMB and 2) an average annual income of 16,250 RMB. The result shows that effect of urbanization on CO 2 emissions varies in terms of income stages and specific regions. Finally, the policy implication was discussed.

The laser beam stabilization system facilitates high-precision correction of the laser beam via the control of the beam position and angle， providing long-term stability. It plays an important role in micro/ nano-laser direct writing and super-resolution imaging. In this paper， a miniaturized laser stabilization sys• tem with error separation technology， which eliminates the coupling error caused by traditional dual-mirror controlling and improves the performance of laser beam stabilization control， is proposed. Comparative ex•

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