Polarized evanescent waves reveal trochoidal dichroism

Area of Science:

• Optics and Photonics
• Materials Science
• Condensed Matter Physics

Background:

• Light polarization sensitivity in matter is typically described by linear and circular dichroism, relating to anisotropy and handedness.
• Near-field evanescent waves exhibit complex polarization states with transverse and longitudinal oscillations, creating trochoidal (cartwheeling) motion.
• Existing polarization effects do not fully capture the geometric nuances of these complex field interactions.

Purpose of the Study:

• To demonstrate and characterize a novel form of polarization sensitivity in matter.
• To introduce and define 'trochoidal dichroism' based on the directionality of trochoidal fields.
• To explore the potential applications of trochoidal dichroism in understanding material and molecular properties.

Main Methods:

• Investigated the interaction of matter with evanescent waves exhibiting trochoidal polarization states.
• Utilized a system of two coupled dipole scatterers to observe differential excitation of plasmon modes.
• Analyzed the system's response to the direction of the trochoidal field motion.

Main Results:

• Demonstrated that matter is sensitive to the direction of trochoidal fields, a phenomenon termed trochoidal dichroism.
• Observed trochoidal dichroism through the differential excitation of bonding and antibonding plasmon modes in the coupled dipole system.
• Established trochoidal dichroism as a distinct geometric basis for polarization sensitivity, fundamentally different from linear and circular dichroism.

Conclusions:

• Trochoidal dichroism represents a new fundamental property of matter's interaction with light polarization.
• This finding expands our understanding of polarization sensitivity beyond traditional linear and circular effects.
• Trochoidal dichroism offers a new method for characterizing systems with cartwheeling charge motion, like light-harvesting antennas.