Banca de DEFESA: PEDRO HENRIQUE DA SILVA SANTOS FERREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : PEDRO HENRIQUE DA SILVA SANTOS FERREIRA
DATE: 27/07/2023
TIME: 10:00
LOCAL: Através de Videoconferência
TITLE:

Four-wave mixing with Hermite-Gauss modes in rubidium vapor

KEY WORDS:

Nonlinear optics. Four-wave mixing. Spatial profile. Hermite-Gauss modes. Gouy
phase.

PAGES: 58
BIG AREA: Ciências Exatas e da Terra
AREA: Física
SUMMARY:

In this work, we present an experimental study on the spatial profile of coherent light generated
in a forward four-wave mixing (FWM) process. We are interested in investigating how the
transverse structure of the incident beams, more specifically of the Hermite-Gauss (HG) modes,
is transferred to the generated signal in this nonlinear process. For the experiment, we used
a continuous wave diode laser to excite a sample of Rubidium atoms, on the 85Rb D2 line,
tuned to the frequency of the 52𝑆1/2 (𝐹 = 3) → 52𝑃3/2 transition. With a Spatial Light
Modulator, we were able to split the laser beam in two and structure them in the desired
modes. These two beams, 𝐴 and 𝐵, with wave vectors ⃗𝑘𝐴 and ⃗𝑘𝐵, and linear orthogonal
polarizations, with quasi-copropagated configuration, were used to induce two FWM signals in
the directions 2⃗𝑘𝐴 −⃗𝑘𝐵 and 2⃗𝑘𝐵 −⃗𝑘𝐴. The spatial profile of incident beams and the two nonlinear
signals were captured by a CMOS camera, and the regimes of a thin or extensive medium
were investigated. We were able to obtain results for a combination of gaussian-HG beams, as
well as HG-HG beams. The profiles obtained by computer simulation were compared with the
experimental measurements. Our theoretical model relies on solving the paraxial equation of
the generated field. It leads to the overlap integrals of the incident beams, which unfold into
some interesting selection rules in the transversal plane, for the thin and extensive medium
regimes, and in the longitudinal axis, only for the long medium regime. Although the extensive
medium regime presents some additional selection rules, the experimental requirements are
difficult to achieve in our system, among them, we highlight the Gouy phase matching. On
the other hand, a good agreement between theory and experiment was observed in the thin
medium regime.

COMMITTEE MEMBERS:
Externo à Instituição - EDUARDO JORGE DA SILVA FONSECA - UFAL
Interno - 1276546 - JOAO CARLOS DE AQUINO CARVALHO
Presidente - 1132318 - SANDRA SAMPAIO VIANNA