Vertically aligned carbon nanotube (VA CNT) arrays are considered as promising thermal interface materials (TIMs) due to their superior out-of-plane thermal conductivities. However the air gaps between adjacent CNTs within the CNT array hinder the in-plane heat transfer, thus significantly degrading the thermal performance of VACNT-based TIMs. To improve the inter-tube in-plane thermal conduction within of VACNT arrays, we propose a novel three dimensional CNT (3D CNT) network structure, where the CNTs in a VACNT array are cross-linked by randomly-oriented secondary CNTs. Three different catalyst preparation methods for the secondary CNT growth are compared in terms of their ability to produce a dense network of secondary CNTs. Among the tested methods, the chemical impregnation method shows a denser 3D CNT network structure. The 3D CNT network grown using this method and is thus chosen for further thermal characterization via a framework especially developed for the evaluation of in-plane thermal properties of such devices. The temperature fields of the corresponding 3D CNT network under different heating powers are recorded using a 15 μm-resolution infrared thermal imaging system. The in-plane thermal conductivity is then derived from these fields using numerical fitting with a 3D heat diffusion model. We find that the in-plane thermal conductivity of the 3D CNT network is 5.40±0.92 W/mK, at least 30 times higher than the thermal conductivity of the primary VACNT array used to grow the 3D CNT network.

In this study, SiN-based gratings with various radius of curvature (r) are designed and fabricated for the optical addressing of trapped Sr + ion. The beam width of the light coupled out from the gratings is investigated using a self-developed Pythonbased data analysis technique. It is found that the r values have insignificant influence on the beam width along x-axis; whereas the beam waist along y-axis reduces from 13.96 to 12.3 µm as r increases from 15 to 20 µm, then increases gradually to 20.51 µm as the r value further increases to 60 µm. The obtained results can provide a versatile solution on the optical addressing of trapped Sr + for applications in quantum engineering.