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

Area of Science:

• Quantum Information Technologies (QITs)
• Materials Science and Engineering
• Optics and Photonics

Background:

• Diamond, particularly nitrogen-vacancy (NV) centers, is a key material for quantum information technologies due to its spin properties.
• High photon collection efficiency is crucial for high-fidelity optical readout of electronic spins in diamond color centers.
• Existing methods for fabricating diamond microstructures, like solid immersion lenses, face challenges with low selectivity for large heights.

Purpose of the Study:

• To address the limitations in fabricating large-height diamond microlenses for enhanced quantum information technology applications.
• To develop a novel fabrication method that overcomes the low selectivity issue between diamond and photoresist materials.
• To demonstrate the successful fabrication of diamond micro-lenses with large, controllable heights.

Main Methods:

• Proposed and demonstrated a dual mask etching technique.
• Utilized an interlayer of single crystalline silicon to enhance selectivity between diamond and photoresist.
• Optimized process parameters for two distinct etching steps to control diamond microstructure formation.

Main Results:

• Successfully fabricated diamond micro-lenses with large, variable heights.
• Achieved high overall selectivity between diamond and photoresist using the dual mask and silicon interlayer method.
• Demonstrated a viable approach for creating essential optical components for diamond-based quantum devices.

Conclusions:

• The dual mask method offers a significant advancement in fabricating large-height diamond micro-lenses.
• This technique is crucial for improving photon collection efficiency in diamond for quantum information processing and sensing.
• The demonstrated fabrication process enables the scalable production of high-performance optical elements for QITs.