Tight focus of light using micropolarizer and microlens

Area of Science:

• Optics and Photonics
• Micro-optics
• Nanotechnology

Background:

• Subwavelength focusing is crucial for advanced optical applications.
• Existing methods often face limitations in achieving high resolution and specific focal spot shapes.

Purpose of the Study:

• To demonstrate subwavelength focusing of light using a novel micro-optic system.
• To characterize the focal spot generated by a binary microlens and a micropolarizer.
• To compare focusing performance with linearly and radially polarized light.

Main Methods:

• Utilized a binary microlens (14 μm diameter, 532 nm focal length, NA=0.997) for focusing a 633 nm laser beam.
• Employed a subwavelength diffractive optical microelement with gold coating to generate a mixture of linearly and radially polarized beams.
• Analyzed focal spot dimensions at full width half-maximum intensity.

Main Results:

• Achieved a near-circular focal spot of (0.35 ± 0.02)λ x (0.38 ± 0.02)λ with an area of 0.105λ².
• Focused linearly polarized light resulted in an elliptical spot of (0.40 ± 0.02)λ x (0.50 ± 0.02)λ.
• Demonstrated the first implementation of subwavelength focusing using a binary microlens and micropolarizer pair.

Conclusions:

• The combined micro-optic system enables precise control over light focusing at the subwavelength scale.
• This technique offers a pathway to enhanced resolution in optical microscopy and lithography.
• The study highlights the potential of integrated micro-optics for next-generation optical devices.