Selection rule for Raman spectra of two-dimensional materials using circularly-polarized vortex light

Area of Science:

• Condensed matter physics
• Materials science
• Optics

Background:

• Circularly polarized vortex light possesses unique spin and orbital angular momenta.
• Two-dimensional (2D) materials exhibit distinct electronic and vibrational properties.
• Raman spectroscopy is a key technique for probing phonon modes in materials.

Purpose of the Study:

• To investigate the conservation of spin and orbital angular momenta of circularly polarized vortex light in 2D materials.
• To establish selection rules for optical absorption based on the angular momentum of incident light.
• To classify Raman active modes in 2D materials based on helicity changes.

Main Methods:

• Theoretical analysis of optical absorption in 2D materials.
• Examination of the Raman tensor for vortex light interactions.
• Classification of Raman active modes into helicity-changing and helicity-conserved categories.

Main Results:

• The selection rules for optical absorption in 2D materials are determined by the spin and orbital angular momentum of the incident vortex light.
• The Raman tensor for vortex light does not alter the symmetry of phonon modes in 2D materials.
• Raman active modes are systematically classified for 2D materials with varying rotational symmetries (2, 3, 4, and 6) under vortex light illumination.

Conclusions:

• Understanding angular momentum conservation is crucial for light-matter interactions in 2D materials.
• The established selection rules and mode classifications provide a framework for advanced spectroscopic analysis.
• This work enables precise control and interpretation of Raman spectra in 2D materials using tailored vortex light.