Overview

Light is a transverse electromagnetic wave. The electric and magnetic fields that compose the light wave always oscillate transversely to the propagation direction; the polarization describes the direction that these electromagnetic fields oscillate.

A polarization analyzer can be incorporated into the optical chain of another cathodoluminescence (CL) mode to provide polarization-filtered or polarization-resolved data. For example, a polarization- and wavelength-filtered map or a polarization- and angle-resolved emission pattern (polarimetry).

Data collection

Polarization filtered: The polarization analyzer consists of a linear polarizer with a user-defined orientation.

Polarization-resolved: The polarization analyzer consists of a quarter-wave plate and linear polarizer. When images are captured over six different analyzer settings, the Stokes parameters that describe the full polarization state of the emitted light may be retrieved.

UsesĀ 

Polarization plays a key role in light-matter interactions and is helpful to study coherence, scattering, birefringence, and chirality finding wide applications in nanophotonic applications. More recently, the degree of polarization has been used to characterize strain in single-crystal semiconductors and insulators. While in (multi-crystalline) samples such as meteorite thin sections, the polarization of the emitted light has also been used to reveal crystal orientation and mineral texture.


An example of how analysis using polarization filtering enhances understanding of a nanophotonic particle. In this example, a 100 nm nanostar (a) exhibits four resonance nodes however, a polarization-filtered spectrum-image (b) demonstrates that the emission consists of two distinct dipole modes that also exhibit different emission patterns (c).

Experiment Brief

Investigating the optical properties of nanophotonic materials far below the diffraction limit

Observation of crystal structure orientation by cathodoluminescence (CL) polarization-filtered spectrum imaging