Large Resonant Third-order Optical Nonlinearity of CdSe Nanocrystal Quantum Dots

Abstract

Resonant third-order nonlinear optical susceptibility and hyperpolarizability of CdSe nanocrystal quantum dots were revealed to be ~2.6×10-20-2.7×10-19 m 2 /V 2 and ~2.2×10-40 m 5 /V 2 by using nanosecond degenerate four-wave mixing at 532 nm. The large nonlinearity of the CdSe nanocrystals is attributed to the resonant excitation and multiple nonlinear optical processes.

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

“…In this article, we present the third-order optical nonlinearities and hyperpolarizabilities of CdS NCs as a function of the concentrations of NCs using polarization-resolved degenerate four-wave mixing (DFWM). The polarization-resolved DFWM involves the comparison of the parallel polarized DFWM and the perpendicularly polarized DFWM, and is usually used to measure different χ (3) ijkl components (where ijkl = x, y, z) and the electronic, molecular reorientation, and thermal contribution to the thirdorder nonlinearity. When the pump and probe laser beams are linearly polarized at 0 o and 90 o , respectively, the intensity distribution of the interaction region is uniform, in other words, there are no intensity modulations because the two laser beams can not interfere with each other.…”

“…toluene ) is assumed to be an addition of the effective third-order susceptibility of CdS NCs (χ NCs_eff ) and that of toluene (χ (3) toluene ) contributions in the dilute approximation [3]. The effective third-order susceptibilities of CdS NCs include the dielectric effect of NCs and toluene.…”

“…The effective third-order susceptibilities of CdS NCs include the dielectric effect of NCs and toluene. The third-order susceptibilities χ The third-order susceptibility χ (3) xyyx of the CdS NCs is correlated to the NCs concentration and the effect of the dielectric confinement [3] C N f…”

“…These characteristics of nanoscale materials modify both their linear and nonlinear optical properties. Also, the spherical NCs in the liquid matrix are considered as an isotropic material's system, which has only three distinguishable polarizationdependent third-order susceptibilities of χ (3) xxxx , χ (3) xxyy , and χ (3) xyyx [5]. A polarization-resolved DFWM identifies the physical origin of the third-order nonlinearity, which is directly related to the nonlinear photonic applications.…”

PMMA-doped CdSe quantum dots as saturable absorber in a Q-switched all-fiber laser

“…One QD material is CdSe, which has unique properties such as a stronger extinction coefficient, narrower band gap [29] , higher quantum confinement effect, higher optical gain, broader absorption profile, better photochemical stability [30] , and larger Stokes shift [30,31] compared to bulk semiconductors. A CdSe QD exhibits resonant non-linearity in slow times scales, which induces huge optical non-linearity, an important feature for generating Q-switched pulsed lasers [32] . The CdSe produced by the QD method has significant advantages over other reinforcements due to the high surface area to volume ratio and the small size distribution.…”