Focusing Lens with Large Numerical Aperture,High Focusing Efficiency and High Transmissivity Based on TiO2 in the Near Infrared Operating
LI Zhen
NIU Huijuan
GAO Song
FAN Xinye
DUAN Xiaofeng
HUANG Yongqing
Abstract：A converging lens based on TiO2 material with a non-periodic concentric circular high-contrast sub-wavelength gratings structure has been designed using phase modulation principles.This lens achieves a large numerical aperture,high focusing efficiency,high transmittance,and low-loss characteristics.It also possesses the advantages of compact size and easy integration.The lens structure was simulated and analyzed using the finite-difference time-domain method.At a working wavelength of 850 nm,the lens had a transmission efficiency of 90.5％,the focal length of approximately 10.4 μm,and the full width at half maximum of the focal spot of 0.61 μm.By analyzing the simulation data,the numerical aperture of the lens was determined to be 0.92,with a high focusing efficiency of 91.07％and the loss of 0.41 dB.The lens balances the contradiction between high numerical aperture and high focusing efficiency,and can a-chieve point convergence close to the diffraction limit in a small device diameter.
Keywords：high-contrast sub-wavelength gratingsnon-periodic concentric circular structurefocusing lenshigh focusing efficiency
Publication Date：2024-02-28
Online Publishing Date：2026-08-28(First online date of this platform, not the publication date of the document)
Pages：7( 16-22 )