Hybrid refractive-diffractive axicons for Bessel-beam multiplexing and resolution improvement

Area of Science:

• Optics and Photonics
• Micro-optics Engineering

Background:

• Optical elements commonly use refraction, diffraction, or reflection for light manipulation.
• Integrating diffractive and refractive functions in a single element enables sophisticated control over light propagation.
• Miniaturized, monolithic optical systems offer advantages in complex beam shaping.

Purpose of the Study:

• To develop hybrid refractive-diffractive micro-axicons by engraving diffraction gratings onto conical surfaces.
• To fabricate these novel optical elements using lithium niobate, a challenging optoelectronic material.
• To characterize the optical performance and validate the design through comparison with theoretical predictions.

Main Methods:

• Utilized gray-scale lithography with high-current focused Xenon (Xe) ion beams.
• Fabricated hybrid micro-axicons with diameters of 230 µm in lithium niobate.
• Engraved linear and circular diffraction gratings with depths less than 400 nm onto the micro-axicon surfaces.

Main Results:

• Successfully realized hybrid refractive-diffractive micro-axicons with integrated gratings.
• Demonstrated excellent agreement between the characterized optical performance and theoretical expectations.
• Confirmed the feasibility of processing lithium niobate for advanced micro-optical components.

Conclusions:

• The fusion of diffractive elements with refractive surfaces enhances device functionality, enabling capabilities like beam multiplexing and improved resolution.
• These monolithic, miniaturized hybrid micro-optical components hold significant potential for applications such as beam shaping in fluorescence microscopy.
• The developed fabrication technique opens avenues for advanced optoelectronic devices utilizing lithium niobate.