ABSTRACT
Diamond nanopillar arrays can enhance the fluorescence collection of diamond color centers, playing a crucial role in quantum communication and quantum sensing. In this paper, the preparation of diamond nanopillar arrays was realized by the processes of polystyrene (PS) sphere array film preparation, PS sphere etching shrinkage control, tilted magnetron sputtering of copper film, and oxygen plasma etching. Closely aligned PS sphere array films were prepared on the diamond surface by the gas-liquid interfacial method, and the effects of ethanol and dodecamethylacrylic acid solutions on the formation of the array films were discussed. Controllable reduction of PS sphere diameter is realized by the oxygen plasma etching process, and the changes of the PS sphere array film under the influence of etching power, bias power, and etching time are discussed. Copper antietching films were prepared at the top of arrayed PS spheres by the tilted magnetron sputtering method, and the antietching effect of copper films with different thicknesses was explored. Diamond nanopillar arrays were prepared by oxygen plasma etching, and the effects of etching under different process parameters were discussed. The prepared diamond nanopillars were in hexagonal close-rowed arrays with a spacing of 800 nm and an average diameter of 404 nm, and the spacing, diameter, and height could be parametrically regulated. Raman spectroscopy and photoluminescence spectroscopy detection revealed that the prepared diamond nanopillar array still maintains polycrystalline diamond properties, with only a small amount of the graphite phase appearing. Moreover, the prepared diamond nanopillar array can enhance the photoluminescence of diamond color centers by approximately 2 times. The fabrication method of diamond nanopillar array structures described in this article lays the foundation for quantum sensing technology based on diamond nanostructures.
ABSTRACT
With the rapid growth in demand for high-speed wireless communication, terahertz (THz) has become one of the most promising techniques. Both atmospheric turbulence and pointing errors are important factors in degrading the performance of THz propagation. We study the performance of a multiple-input/multiple-output (MIMO) system in the THz band under the combined influences noted above. Especially, we take the impact on amplitude and phase caused by turbulence into consideration. We adopt the Padé approximation to analyze the probability density function of the channel coefficient in equal gain combining and derive the bit error rate by the Meijer-G function. The curve-fitting results of theoretical analysis are in good agreement with the actual measurements in the THz band. Therefore, it can be deduced that the exponentiated Weibull model can also be applied in the THz band. Then, we verify the theoretical results by Monte Carlo simulation. We find that turbulence is a more significant cause, which deteriorates communication performance in a larger scale of the MIMO system.
