This paper describes an effective approach to order gold nanorods (NRs) within cylindrically confined microdomains of block copolymer-(BCP-) based supramolecular assemblies. Individual BCP micelles encapsulated with wellordered NRs can be obtained by disassembling the supramolecular structures. The mismatch of binary polymer brushes with different lengths on the surface of the NRs was used to effectively improve the dispersion of the NRs within polymer matrix, due to enhanced wetting of the brushes by surrounding mismatch polymers. This enables us to quantitatively explore the location and orientation of the NRs within confined geometries. By varying the content of NRs, the aspect ratio of the NRs, or the diameter of the cylindrical BCP micelles, the orientation of the NRs within micelles can be tuned to form one-dimensional nanostrings with end-to-end organization of NRs along the micelles or with side-by-side twisted arrangement of NRs perpendicular to the micelles. UV−vis spectroscopy measurements and finitedifference time-domain (FDTD) calculations confirm that our approach provides a simple yet versatile route to tune the optical properties of the hybrid micelles by controlling the ordering of the NRs. This work provides guidelines for dispersing other functional anisotropic NPs, and lays groundwork for the fabrication of optical and electronic devices.

A novel high-efficiency silicon-chip-to-fiber grating coupler is investigated here. By introducing a dual layer grating structure with an inter-layer lateral shift to mimic 45° tilted mirror behavior, perfectly vertical coupling is successfully demonstrated. Our numerical results show that a peak silicon-chip-to-fiber coupling efficiency about 70% is possible near 1550 nm. Meanwhile, for the entire telecom C-band, i.e. wavelengths from 1530 nm to 1565 nm, the coupling efficiency is > 50% and the back reflection is less than < 1%. Our proposed high-performance silicon perfectly vertical coupling structure is suitable for interfacing with multi-core fiber platform, which may play an important role in the future CMOS photonic integration technology.

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We experimentally investigated concurrent parametric downconversion processes in a two-dimensional hexagonally poled lithium tantalate crystal. The substantial enhancement of parametric gain was observed when concurrent processes shared a common parametric beam. Both degenerate and nondegenerate concurrent parametric downconversion processes were studied. Analyses of the spatial forms and output angles showed a strong dependence on the working temperature, during which a well-defined beamlike parametric output was observed. Our results will stimulate the design for coherent high-gain generation of multiple parametric beams and also shed light on the compact engineering of path-entanglement with specific spatial forms based on concurrent spontaneous parametric downconversion processes.

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