Multispectral Holographic Intensity and Phase Imaging of Semitransparent Ultrathin Films

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Characterizing ultrathin films is crucial for advanced material applications.
• Existing optical methods often lack the precision for ultrathin, semitransparent, or absorbing materials.
• Accurate determination of optical properties is essential for material design and quality control.

Purpose of the Study:

• To develop and demonstrate a novel optical characterization method for ultrathin semitransparent and absorbing materials.
• To extract both intensity and phase information from transmitted optical fields for detailed analysis.
• To validate the method's performance using fabricated ultrathin metal films.

Main Methods:

• Utilized a lateral-shearing interferometric microscopy (LIM) technique with phase-shifting.
• Fabricated and measured cupric oxide (CuO) seeded gold ultrathin metal films (UTMFs) with varying thicknesses (2-27 nm).
• Employed multilayer thin film interference and parametric modeling to analyze optical properties and complex refractive indices.

Main Results:

• Successfully imaged UTMF samples in the spectral range of 475-750 nm.
• Fitted model parameters to measured data, determining complex refractive indices for different thicknesses.
• Demonstrated the capability to extract both intensity and phase for imaging and material property determination.

Conclusions:

• The proposed LIM technique offers a powerful tool for optical characterization of ultrathin films.
• Combined intensity and phase imaging enables precise determination of material properties like complex refractive indices.
• This method shows high potential for quality control and optical property analysis of semitransparent thin films.