Large-Scale High-Accuracy and High-Efficiency Phase Plate Machining.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Diffractive optical elements (DOEs) are crucial for various optical applications.
• Efficient and cost-effective fabrication methods for high-performance DOEs are in demand.
• Multilevel phase plates require precise manufacturing techniques.

Purpose of the Study:

• To develop an efficient and precise method for fabricating multifunctional, multilevel phase plates on quartz substrates.
• To demonstrate the capability of the developed system for producing Fresnel lens and axicon phase plates.
• To assess the potential for reducing production costs and enabling customized mass production of DOEs.

Main Methods:

• Utilized a polygon scanner-based femtosecond laser photolithography system for high-speed, high-resolution pattern writing.
• Integrated inductively coupled discharge plasma reactive-ion etching (ICP-RIE) for precise depth control and edge definition.
• Employed infinite field-of-view (IFOV) processing for direct writing on large wafers.

Main Results:

• Achieved a femtosecond laser photolithography scanning speed of 5 m/s and preparation efficiency of 15 cm²/h.
• Ensured overlay alignment accuracy below 100 nm and writing resolution of 500 nm.
• Controlled ICP-RIE etching depth error within ±5 nm and mask-to-mask edge error below 1 μm.
• Fabricated 8-level Fresnel lens and axicon phase plates with >93% diffraction efficiency.
• Demonstrated one-time direct writing preparation of various phase plate masks on a 6-inch wafer.

Conclusions:

• The combined femtosecond laser photolithography and ICP-RIE technology offers an efficient and accurate method for producing quartz phase plates.
• The developed system facilitates the direct writing of customized diffractive optical elements, reducing production costs.
• This approach is expected to promote the customized mass production of quartz substrate diffractive optical elements.