Structured lens formed by a 2D square hole array in a metallic film

Area of Science:

• Optics and Photonics
• Metamaterials and Plasmonics

Background:

• Phase modulation is crucial for advanced optical devices.
• Subwavelength structures in metallic films offer unique optical properties.
• Existing methods for phase control can be complex or limited in scope.

Purpose of the Study:

• To propose and validate a method for phase modulation using variant square holes in metallic films.
• To design and analyze a structured lens based on this method.
• To achieve precise focusing capabilities for optical applications.

Main Methods:

• Development of a fundamental mode approximation model for phase retardation analysis.
• Design of a structured lens utilizing a 2D array of subwavelength square holes.
• Numerical simulations using the finite-difference time-domain (FDTD) method for validation.

Main Results:

• Theoretical analysis and numerical simulations show good agreement.
• A structured lens with a numerical aperture of 0.583 and focal length of 240 micrometers was designed.
• The designed lens achieved a focal spot close to the diffraction limit.

Conclusions:

• The proposed method effectively modulates phase using variant square holes in metallic films.
• The designed structured lens demonstrates high focusing performance.
• This approach offers a viable route for creating advanced optical components.