Demonstration of diamond microlens structures by a three-dimensional (3D) dual-mask method

Fabrication of concave microlenses on a diamond by a spin coating process

In this study, to fabricate diamond concave microlenses in a simple manner, an approach that combines a spin coating process with subsequent dry etching was demonstrated. First, photolithography was used to produce cylindrical holes in the photoresist layer on the diamond surface. Then, another photoresist was spin coated to fill the holes, and the concave structures with meniscus shapes were then obtained because of centrifugal force and interfacial tension. Finally, diamond concave microlenses were formed by transferring photoresist concave structures onto a diamond substrate using a dry etching technique. The fabricated diamond microlens exhibits a low surface roughness with nanometers as well as high-quality imaging and focusing performances, which is expected to have a wider range of potential applications under harsh and special conditions.

Patterning of diamond with 10 nm resolution by electron-beam-induced etching

We report on mask-less, high resolution etching of diamond surfaces, featuring sizes down to 10 nm. We use a scanning electron microscope (SEM) together with water vapor, which was injected by a needle directly onto the sample surface. Using this versatile and low-damage technique, trenches with different depths were etched. Cross sections of each trench were obtained by focused ion beam milling and used to calculate the achieved aspect ratios. The developed technique opens up the possibility of mask- and resist-less patterning of diamond for nano-optical and electronic applications.

Fabrication of Diamond Submicron Lenses and Cylinders by ICP Etching Technique with SiO2 Balls Mask

Submicron lenses and cylinders exhibiting excellent properties in photodetector and quantum applications have been fabricated on a diamond surface by an inductively-coupled plasma (ICP) etching technique. During ICP etching, a layer containing 500 nm diameter balls of SiO₂ was employed as mask. By changing the mixing ratio of O₂, Ar and CF₄ during ICP etching, several submicron structures were fabricated, such as cylinders and lenses. The simulation results demonstrated that such submicron structures on a diamond’s surface can greatly enhance the photon out-coupling efficiency of embedded nitrogen-vacancy center.

SiNx-Si interlayer coupler using a gradient index metamaterial

In this work, we demonstrate a metamaterial (MM)-based SiN_x-Si interlayer coupler. A gradient index (GRIN) MM was employed to achieve refractive index matching, balancing the large difference in the refractive index between Si (∼3.42) and SiN_x (∼2). In addition, a two-layer SiN_x interlayer coupler was proposed to further minimize the coupling loss and interlayer crosstalk. Finally, we demonstrated a three-dimensional (3D) SiN_x-Si interlayer coupler with the -0.6  dB insertion loss per layer propagation, with the 40 nm 1-dB-bandwidth (1530-1570 nm) and <-45  dB interlayer crosstalk. These promising results demonstrate the great potential of a GRIN MM-based SiN_x-Si interlayer coupler in 3D photonic integration.

Investigation of the occupancy ratio dependence for microlens arrays on diamond

Diamond microlens arrays with a high occupancy ratio were fabricated by an improved thermal reflow method.