Two-modulator generalized ellipsometry: theory

Area of Science:

• Optics and Photonics
• Materials Science
• Surface Science

Background:

• Ellipsometry is a powerful optical technique for characterizing thin films and surfaces.
• Traditional ellipsometry methods can be limited in their ability to fully determine sample properties.
• Mueller matrix ellipsometry provides more comprehensive information about anisotropic and depolarizing samples.

Purpose of the Study:

• To introduce a new ellipsometer design capable of measuring all elements of a sample's Mueller matrix.
• To demonstrate the versatility of the new instrument for various material characterization applications.
• To overcome limitations of existing ellipsometers in complex sample analysis.

Main Methods:

• The new ellipsometer utilizes two photoelastic modulator-polarizer pairs operating at different resonant frequencies.
• The time-dependent intensity of the light beam is analyzed to extract Mueller matrix elements.
• Measurements are performed in a single configuration, with additional elements accessible by changing azimuthal angles.

Main Results:

• All 16 elements of the sample Mueller matrix can be obtained through analysis of the complex intensity data.
• Nine Mueller matrix elements are measurable in a single configuration.
• The remaining seven elements are accessible by adjusting the azimuthal angles of the photoelastic modulators.

Conclusions:

• The developed ellipsometer provides a complete characterization of sample Mueller matrices.
• This technique is sufficient for completely characterizing various real-world scenarios, including film growth, anisotropic materials, and depolarization.
• The instrument offers enhanced capabilities for advanced optical metrology and materials analysis.