Poster + Paper
10 June 2024 Optimal filtering of polarisation-controlled Brillouin scattering in elliptical optophononic resonators
Author Affiliations +
Conference Poster
Abstract
Accessing acoustic phonons at high frequencies in nanostructures becomes more and more essential in nanoelectronics, nano- and opto-mechanics and quantum technologies, as phonons can strongly interact with electrons and photons at the nanoscale. In spontaneous Brillouin scattering processes, the scattered photons energy, direction and polarization are constrained by selection rules for a given input state. These selection rules are usually considered as intrinsic material properties in crystalline solids and the polarization of the scattered photons depends on the polarization of the excitation. In this work, we use elliptical optophononic micropillar resonators to control these optical polarization selection rules. The degeneracy of the optical cavity modes of circular micropillars is lifted due to the elliptical cross-section of the micropillars, leading to two cavity modes orthogonally polarized and split in energy. The optical field polarization state will depend on both orthogonal cavity modes and their associated polarization states. Therefore, an incident laser beam linearly polarized along the diagonal axis of the elliptical pillar undergoes a wavelength dependent polarization rotation. By choosing the polarization and wavelength of the incident laser, we demonstrate that the polarization state of the incident and reflected laser and the Brillouin scattering signal are different. In this way, background-free spontaneous Brillouin scattering spectra can be efficiently measured in a cross-polarization scheme down to 18 GHz. Here, we theoretically and experimentally explore the optimal conditions for the polarization and wavelength of the incident laser, and the ellipticity of the micropillars, to improve the polarization-based filtering applied to Brillouin spectroscopy.
(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.
E. Mehdi, A. Rodriguez, P. Priya, E. R. Cardozo de Oliveira, A. Harouri, I. Sagnes, L. Le Gratiet, M. Morassi, A. Lemaître, L. Lanco, M. Esmann, and N. D. Lanzillotti-Kimura "Optimal filtering of polarisation-controlled Brillouin scattering in elliptical optophononic resonators", Proc. SPIE 12991, Nanophotonics X, 1299119 (10 June 2024); https://doi.org/10.1117/12.3022001
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KEYWORDS
Polarization

Laser scattering

Reflection

Optical filters

Raman scattering

Optimal filtering

Poincare sphere

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