Design of transmission multilayer polarizer for soft X-ray using a merit function

Area of Science:

• Optics and Photonics
• Materials Science
• X-ray Physics

Background:

• Soft X-ray transmission multilayer polarizers are essential for various applications.
• Existing design methods may not achieve optimal performance characteristics.
• Single-wavelength optimization is critical for specific experimental setups.

Purpose of the Study:

• To develop a new, optimized method for designing soft X-ray transmission multilayer polarizers.
• To utilize a specific merit function to enhance polarizer performance.
• To investigate the impact of layer structure and roughness on polarizer characteristics.

Main Methods:

• A novel merit function, defined as the product of p-transmittance throughput and the logarithm of the transmittance polarization ratio, was developed.
• The method was applied to design Mo/Si multilayer polarizers at 13.0 nm.
• Calculated characteristics were compared against traditional methods and existing literature.
• The influence of surface roughness on Mo/Si and La/B4C multilayer polarizers was analyzed at 13.0 nm and 6.7 nm, respectively.

Main Results:

• The merit function approach yielded optimal results with a throughput of 30.0% and a polarization ratio of 202 for Mo/Si at 13.0 nm.
• This method allows for the design of polarizers with significantly higher polarization ratios or p-transmittance.
• Surface roughness was found to critically impact polarizer performance, especially in the shorter wavelength region.

Conclusions:

• The developed merit function provides an effective strategy for designing high-performance soft X-ray multilayer polarizers.
• Optimization of layer number and thickness is key to maximizing polarizer performance.
• Understanding and mitigating roughness effects are crucial for shorter wavelength applications.