Inverse-designed large field-of-view polychromatic metalens for tri-color scanning fiber endoscopy

Area of Science:

• Optics and Photonics
• Nanotechnology
• Biomedical Imaging

Background:

• Metalenses offer miniaturization potential for imaging systems but suffer from chromatic aberrations, limiting multi-color applications.
• Traditional refractive lenses are bulky and unsuitable for confined spaces, driving the need for advanced optical components.
• Addressing chromatic aberration is crucial for developing practical metalenses for real-world imaging scenarios.

Purpose of the Study:

• To develop and demonstrate an inverse-designed polychromatic metalens with low dispersion across multiple wavelengths.
• To enable miniaturized, multi-color imaging systems, specifically for applications like endoscopes.
• To overcome the chromatic aberration limitations of traditional metalenses.

Main Methods:

• Inverse design was employed to create a polychromatic metalens with specific optical parameters (680 μm diameter, 400 μm focal length).
• The metalens was designed for low dispersion at three distinct wavelengths (643 nm, 532 nm, 444 nm).
• The metalens was utilized to collimate and steer light for scan-based imaging, evaluating its field-of-view and angular resolution.

Main Results:

• The developed metalens exhibits low dispersion across 643 nm, 532 nm, and 444 nm.
• It generates scanning beams with a 70° field-of-view and achieves near-diffraction-limited 0.5° angular resolution.
• Average relative efficiencies were 32% on-axis and 13% across the field-of-view for the design wavelengths.

Conclusions:

• The inverse-designed polychromatic metalens effectively addresses chromatic aberrations, paving the way for advanced miniaturized imaging.
• This technology holds significant promise for enhancing the capabilities of endoscopes and other compact imaging devices.
• The demonstrated metalens performance highlights its potential for multi-color imaging in space-constrained applications.