Structured surface reflector design for oblique incidence beam splitter at 610 GHz.

Area of Science:

• Electromagnetics and Optics
• Applied Physics
• Metamaterials and Nanophotonics

Background:

• Beam splitters are crucial optical components for manipulating light.
• Designing efficient beam splitters for millimeter-wave and terahertz frequencies presents significant challenges.
• Structured surfaces offer a promising route for advanced optical functionalities.

Purpose of the Study:

• To develop and validate an iterative algorithm for designing structured surface reflectors as beam splitters.
• To achieve precise control over beam splitting at GHz and THz frequencies.
• To demonstrate experimental feasibility and efficiency of the designed beam splitters.

Main Methods:

• An iterative alternate projection-based algorithm was employed for designing the surface profile.
• A 610 GHz beam splitter was designed to generate four equal-intensity beams at specific angles.
• A prototype was fabricated and characterized experimentally.

Main Results:

• The designed reflector successfully split a single beam into four equal-intensity beams at ±12.6°.
• Experimental measurements showed excellent agreement (within 1%) with Feko simulations.
• The fabricated beam splitter achieved a measured efficiency of 78% under oblique incidence.

Conclusions:

• The developed algorithm is effective for designing structured surface beam splitters at high frequencies.
• Experimental results validate the computational method and the performance of the beam splitter.
• This work paves the way for advanced beam-forming applications in GHz and THz regimes.