Linear and nonlinear optical properties of human hemoglobin.

In this study, we investigated the possibility of interactions between the solvent molecules with the Heme group in the human hemoglobin. The results of this study answer a key question: whether the interactions of the Heme unit with its surroundings are interdependent or independent of the protein units of human hemoglobin. Contributions of the intermolecular interactions were determined by exploiting the solvatochromism spectroscopic data by Kamlet-Taft (KAT) polarity functions. Solvent polarity effects on the nonlinear properties of the Heme's groups in the human hemoglobin (Hb) were investigated via the Z-scan method. The experimental results obtained with spectroscopic and nonlinear optical parameters (absorption coefficient and refractive index) show that the mechanism of solvation and the interactions of Heme are controlled by suitable configuration of the protein units of hemoglobin. In other words, interactions of the Heme with α- and ß-globins are an effective factor in controlling the optical behavior of Heme.

Flexoelectric coefficients enhancement via doping carbon nanotubes in nematic liquid crystal host.

Flexoelectric coefficients of carbon nanotube (CNT) doped nematic liquid crystals (NLCs) are studied based on the Helfrich theory. Weak and hard anchoring conditions between the NLC molecules and CNTs are considered. The volume fraction of the CNTs in nematic host is assumed to be low, which makes nanotubes aggregation phenomena negligible. Also, the length of doped CNTs is assumed to be lower than 10µm, so these rigid rods with low concentration cannot possess any flexoelectric polarization by themselves, only their presence modifies the flexoelectric coefficients of the NLC system. The Landau-de Gennes theory is used to calculate the order parameter changes in the medium. Also, the numerical density definition is renewed in the presence of nanotubes. It is shown that in the nematic phase the flexoelectric coefficients increase along with the increase of the coupling strength and temperature. The enhancement in flexoelectric coefficients is more significant in hard anchoring conditions than in the weak anchoring case. The flexoelectric coefficients increase up to 5-fold is calculated near the phase transition temperature, which is in good accordance with the experimental reported data.

Control of the Goos-Hänchen shifts of a probe light beam using phase tunability of the intracavity medium.

This paper presents the Goos-Hänchen (GH) shifts of a probe light beam in a fixed cavity configuration containing the three level V-type atomic medium. We found that in the presence of decay-induced interference, the lateral shifts of both the reflected and transmitted probe light beam can easily be controlled just by the relative phase of applied fields. We also discuss the intensity of the applied field on GH shifts of the reflected and transmitted probe light beam.

Large Kerr index with amplification in an open four-level atomic system with twofold lower levels.

This paper presents a new freedom, which is the result of atomic injection and exit rates from a cavity associated with an open system, thus leading to a remarkable giant Kerr nonlinearity with applications in all-optical switching. The influence of atomic injection and exit rate from the cavity on nonlinear susceptibility of an open four-level Λ-type atomic system with twofold lower levels is investigated. It is found that large Kerr nonlinearity accompanied with probe gain can be obtained by adjusting the atomic injection rates and exit rate from the cavity, which is completely different from those presented in previous closed atomic systems. Phase control of Kerr nonlinearity in such an open atomic system is then studied.