Axicon metalens for broadband light harvesting

Area of Science:

• Optics and Photonics
• Materials Science
• Sensor Technology

Background:

• Composite metal-oxide semiconductor sensors require efficient light management for optimal performance.
• Traditional sensors often suffer from limited light absorption and spatial distribution.
• Energy harvesting is crucial for low-power and autonomous sensor applications.

Purpose of the Study:

• To design, fabricate, and characterize an axicon metalens for enhanced energy harvesting in sensors.
• To investigate the light-focusing and beam-deflecting properties of the metalens.
• To evaluate the impact of the metalens on sensor optical transmission and performance.

Main Methods:

• Design and fabrication of an axicon metalens with a central disc and surrounding nanoposts.
• Characterization using micro-hyperspectral imaging to measure optical transmission.
• Comparison of sensor performance with and without the axicon metalens.
• Finite-difference time-domain (FDTD) simulations for theoretical validation.

Main Results:

• The axicon metalens successfully focuses light onto the sensor's sensitive area and harvests light from adjacent pixels.
• Normalized peak transmission increased by up to 250% at 700 nm compared to a blank film.
• Experimental results showed good agreement with FDTD simulations.
• Demonstrated ultra-broadband energy-harvesting capabilities.

Conclusions:

• The developed axicon metalens significantly enhances sensor light-harvesting efficiency.
• The metalens technology offers a promising solution for improving sensor performance in various applications.
• Potential applications include advanced surveillance systems and Internet of Things devices.