High-efficiency, broad-bandwidth metal/multilayer-dielectric gratings

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metal/multilayer-dielectric gratings (MMDGs) are crucial optical components.
• Achieving broadband operation and high diffraction efficiency simultaneously presents a significant challenge.
• Existing fabrication methods often face limitations in achieving desired grating performance.

Purpose of the Study:

• To design and fabricate an 800 nm center-wavelength MMDG with broadband characteristics and high diffraction efficiency.
• To investigate the use of a composite grating ridge structure for improved performance and manufacturability.
• To demonstrate the practical feasibility of the proposed MMDG design using existing fabrication technologies.

Main Methods:

• Utilized a trapezoidal grating ridge design incorporating Hafnium Dioxide (HfO2) and Silicon Dioxide (SiO2) layers.
• Leveraged the combined optical and material properties of SiO2 and HfO2 to enhance grating performance.
• Employed existing fabrication technologies for the realization of the MMDG structure.

Main Results:

• Successfully fabricated an 800 nm center-wavelength MMDG.
• Achieved a demonstrated bandwidth of 163 nm.
• Obtained a -1st-order diffraction efficiency exceeding 90% across the operational bandwidth.
• The fabricated MMDG exhibited high performance consistent with design specifications.

Conclusions:

• The developed MMDG design offers a viable solution for broadband, high-efficiency diffraction applications.
• The composite SiO2/HfO2 grating ridge structure simplifies fabrication while maintaining high performance.
• The demonstrated large fabrication tolerances indicate the robustness and practical applicability of the MMDG technology.