Cadmium chalcogenide semiconductor nanocrystals for optical power limiting application

Abstract

Cadmium chalcogenide nanocrystals at ~2-10 nm were synthesized using with a chemical colloidal reaction technique. Strong blue-shifts of the CdTe, CdSe and CdS nanocrystals absorption bandedge and the atomic-like discrete energy states indicate an exciton quantum confinement. Z-scan and I-scan nonlinear spectroscopy revealed that the CdTe nanocrystals quantum dot in toluene (~8 x 10 -5 mol/L) has the negative nonlinearity (self-defocusing) with ~ -1 x 10 -13 m 2 /W and a high nonlinear figure of merit of ~200. For the optical power self-limiting experiment, the CdTe nanocrystals was almost opaque above ~0.8 MW/cm 2 at near valley (z~6.9 cm) of Z-scan. The nonlinear optical applications include optical power self-limiting for homeland security of human-eye and sensor protection against potential laser terror threats, and agile laser threats on the battle field, optical switching, and pulse shaping in optical parametic oscillator/optical parametic generator.

Optical limiting in CdTe nanocrystals embedded in polystyrene

“…Moreover, this nonlinearity is controllable by the size of the QDs. This has already been proven by our previous in-depth experimental work and is in accordance with the results of other authors [2][3][4][5][6][7][8][9].…”

Polarization‐resolved degenerate four‐wave mixing of CdS nanocrystals in a nonresonant region

“…It shows a strong blue shift of bandgap energy from the bulk state (E g, bulk ~513 nm) and the first and second exciton absorption peaks around 387, and 349 nm, respectively [2]. …”

“…The detailed preparation of cadmium chalcogenide semiconductor NCs (CdS, CdSe, and CdTe NCs) was described in our previous report [2]. The average diameter of CdS NCs was www.pss-c.com near 2.6 nm, which is smaller than the bulk exciton Bohr radius (~3.0 nm).…”