Enhanced double resonance Raman scattering in multilayer graphene with broadband coherent anti-Stokes Raman...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nonlinear Optics

Background:

• Graphene exhibits significant nonlinear optical properties due to its unique electronic band structure.
• Coherent anti-Stokes Raman scattering (CARS) is a powerful technique for probing vibrational modes in materials.
• Previous studies noted a time-resolved dip-to-peak evolution in graphene's CARS response influenced by resonances.

Purpose of the Study:

• To report a significantly enhanced double resonance Raman mode in multi-layer graphene.
• To investigate the underlying mechanisms contributing to this enhanced response.
• To explore the potential of two-dimensional materials in advanced optical applications.

Main Methods:

• Broadband CARS spectroscopy was employed to measure the Raman response.
• Analysis focused on multi-layer graphene samples.
• Comparison of CARS and spontaneous Raman (SR) scattering intensities was performed.

Main Results:

• A novel, enhanced double resonance Raman mode beyond the G mode was identified in multi-layer graphene.
• A notable difference in the CARS to SR intensity ratio was observed for this mode.
• The enhanced response is potentially linked to preferential low-frequency phonon activation in impulsive stimulated Raman scattering (ISRS) and reduced dephasing rates.

Conclusions:

• The study demonstrates a method to enhance and observe specific Raman modes in graphene.
• Findings suggest a deeper understanding of coherent Raman scattering in two-dimensional materials.
• This work provides a foundation for exploring the coherent Raman response of novel 2D materials.