Excitonic nonlinear absorption in CdS nanocrystals studied using Z-scan technique

Abstract

Irradiance dependence of excitonic nonlinear absorption in Cadmium Sulfide (CdS) nanocrystals has been studied by using Z-scan method with nanosecond laser pulses.The wavelength dependence of nonlinear absorption has also been measured near the excitonic transition of 1S(e) -1S 3/2 (h). We observe the saturable absorption, which can be described by a third-order and a fifth-order nonlinear process for both 3.0-nmsized and 2.3-nm-sized CdS nanocrystals. The experimental results show that the excitonic nonlinear absorption of CdS nanocrystals is greatly enhanced with decreasing particle size. A two-level model is utilized to explain both irradiance and wavelength dependence of the excitonic nonlinearity.

Synthesis and optical properties of MPTMS-capped CdS quantum dots embedded in TiO2 thin films for photonic applications

“…Despite a lot of noise ascribed to the apparatus, we were able to evaluate the order of magnitude of the Kerr refractive index for the solutions using the conventional Z-scan equation [11]. The non-linear absorption is too small to be detected here because the observation of absorptive non-linearities generally requires nearly excitonic resonance in CdS NP solutions [3,22].…”

Nonlinear optical absorption and reflection of single wall carbon nanotube thin films by Z-scan technique

“…CdS thin films, 20 except for C 60 films 5 . Furthermore, the present n 2 value displays about two orders of magnitude greater than that of MWNT films.…”

Нелинейно-оптические свойства квантовых точек CdS/ZnS в матрице из высокомолекулярного поливинилпирролидона

“…Полупроводниковые квантовые точки (КТ), такие как CdS, обладают сильными нелинейными оптическими свойствами как при пикосекундном, так и при нано-секундном воздействии [1][2][3][4][5][6][7][8][9][10]. Нелинейные структуры, содержащие КТ в золях на основе поливинилпирроли-дона (PVP) или пленках, перспективны в оптическом ограничении лазерного излучения, а также представ-ляют интерес при разработке твердотельных нелиней-ных структур [2].…”