# Towards Polarization-based Excitation Tailoring for Extended Raman Spectroscopy

## TL;DR

This paper introduces a polarization-tailored light method for Raman spectroscopy of nanostructures, enabling access to electric field components perpendicular to the substrate without sample tilting or complex prep.

## Contribution

It presents a novel experimental approach using focused cylindrical vector beams to control electromagnetic fields in Raman spectroscopy of individual nanostructures.

## Key findings

- Raman spectra depend on nanostructure position relative to the focal field.
- Spectra reveal interactions with transverse or longitudinal electric fields.
- Method allows characterization of all Raman modes in nanosystems.

## Abstract

Undoubtedly, Raman spectroscopy is one of the most elaborated spectroscopy tools in materials science, chemistry, medicine and optics. However, when it comes to the analysis of nanostructured specimens, accessing the Raman spectra resulting from an exciting electric field component oriented perpendicularly to the substrate plane is a difficult task and conventionally can only be achieved by mechanically tilting the sample, or by sophisticated sample preparation. Here, we propose a novel experimental method based on the utilization of polarization tailored light for Raman spectroscopy of individual nanostructures. As a proof of principle, we create three-dimensional electromagnetic field distributions at the nanoscale using tightly focused cylindrical vector beams impinging normally onto the specimen, hence keeping the conventional beam-path of commercial Raman systems. Using this excitation scheme, we experimentally show that the recorded Raman spectra of individual gallium-nitride nanostructures of sub-wavelength diameter used as a test platform depend sensitively on their location relative to the focal vector field. The observed Raman spectra can be attributed to the interaction with transverse or longitudinal electric field components. This novel technique may pave the way towards a characterization of Raman active nanosystems using full information of all Raman modes.