Polarization helicity and the optical spin-orbit Hall effect.

Area of Science:

• Optics
• Quantum Optics
• Condensed Matter Physics

Background:

• The optical spin-orbit Hall effect demonstrates the spatial separation of spin angular momentum (SAM) and orbital angular momentum (OAM).
• This effect is observable in radially polarized light and influenced by the initial phase of the polarization state, affecting its distribution.
• Controlling this separation is crucial for applications in optical manipulation and information processing.

Purpose of the Study:

• To introduce and utilize polarization helicity as a parameter to characterize the influence of initial phase on the optical spin-orbit Hall effect.
• To investigate the modulation of polarization helicity in radial polarization states and its impact on SAM and OAM separation.
• To explore the potential for controlling light polarization states in uniaxial crystals.

Main Methods:

• Theoretical analysis of the optical spin-orbit Hall effect for radially polarized light.
• Introduction of polarization helicity to quantify the effect of initial phase.
• Mathematical modeling to determine the conditions for maximum SAM and OAM separation and their sign evolution.

Main Results:

• Polarization helicity of radial polarization states can be modulated by adjusting the initial phase; it is zero for high-order polarization states.
• Maximum separation magnitude of SAM and OAM occurs when the initial phase is π/4 or -π/4.
• The sign of SAM and OAM separation depends on polarization helicity and crystal anisotropy, evolving sinusoidally.
• Incident radially polarized light transforms into elliptical polarization states based on polarization helicity.

Conclusions:

• Polarization helicity provides a new framework for understanding and controlling the optical spin-orbit Hall effect.
• The findings offer a method for modulating the polarization state of light within uniaxial crystals, deepening the understanding of spin-orbit coupling in vector beams.