Infrared diffractive filtering for extreme ultraviolet multilayer Bragg reflectors.

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Extreme ultraviolet (EUV) radiation requires specialized optics for manipulation and control.
• Current optical components often lack the ability to selectively filter specific wavelengths, limiting applications.
• Developing broadband radiation sources necessitates advanced filtering solutions.

Purpose of the Study:

• To design and fabricate a novel hybrid mirror capable of reflecting EUV radiation.
• To achieve spectral-selective suppression of longer-wavelength radiation, specifically infrared (IR).
• To demonstrate the proof of principle for this hybrid filtering technology.

Main Methods:

• Integration of a lamellar grating substrate with an EUV-reflecting multilayer coating (Mo/Si).
• Fabrication using masked deposition of silicon gratings followed by multilayer coating.
• Characterization of reflectance at 13.5 nm (EUV) and suppression at 10 μm (IR).

Main Results:

• The hybrid mirror demonstrated 61% reflectance at 13.5 nm EUV wavelength.
• Achieved a 70x suppression rate for specular reflection at 10 μm IR wavelength.
• Validated the grating phase-shift resonance principle for spectral-selective filtering.

Conclusions:

• The developed hybrid mirror effectively functions as a Bragg reflector for EUV radiation.
• Simultaneous spectral-selective suppression of IR radiation was successfully demonstrated.
• This filtering principle is applicable to various applications utilizing broadband radiation sources.