Wubiao Duan

Ultrafast third-order nonlinear optical properties of ZnPc(OBu)6(NCS)/DMSO solution

The ultrafast third-order nonlinear optical properties of ZnPc(OBu)(6)(NCS)/dimethyl sulfoxide solution are investigated by optical Kerr effect (OKE) and pump-probe techniques with femtosecond pulses. Using CS(2) as the reference, the third-order susceptibility of the sample solution is obtained as about 1.40x10(-14) esu at a concentration of 3.00x10(-5) M. The second hyperpolarizability for the sample solution is deduced to be as large as 2.35x10(-31) esu. The dynamic characteristics of the nonlinear optical response and the origins of the OKE signal can be attributed to excited singlet state populations.

Strong reverse saturable absorptive effect of an ultrathin film containing octacarboxylic cobalt phthalocyanine and polyethylenimine

A novel nanoscopic composite film with alternating layers consisting of anionic octacarboxylic cobalt phthalocyanine [CoPc(COONa)8] and cationic polyethylenimine (PEI) has been fabricated by an electrostatic, layer-by-layer, self-assembly technique. UV-vis spectroscopy revealed consecutive regular deposition of CoPc(COONa)8/PEI onto a quartz slide. The films delicate nanostructure was characterized by atomic force microscopy and small angle X-ray diffraction. Third-order nonlinear properties of the film performed using Z-scan measurements with 21 ps laser pulses at the incidence wavelength of 532 nm showed rather strong, nonlinear reverse saturable absorption.

Third-order nonlinear optical properties of self-assembled thin films containing tetracarboxylic copper phthalocyanine

Films with alternating layers containing anionic tetracarboxylic copper phthalocyanine [CuPc(COONa)4] and cationic polydiallydimethylammonium chloride (PDDA) were fabricated by electrostatic self-assembled layer-by-layer (LBL) technique. The delicate structure of the film was characterized by a series of techniques. The third-order nonlinear optical properties of the film were measured by the Z-scan technique with laser duration of 4 ns and 21 ps at the wavelength of 532 nm. The film exhibited excellent nonlinear absorption and self-focusing effect. The second-order molecular hyperpolarizability γ value of the film was much larger than that of CuPc(COONa)4 aqueous solution under the irradiation of whether ns or ps pulses. A series of damage experiments of the film for the intense laser pulses were conducted to prove the reliability of the experimental results under the conditions.

Preparation of nickel(II)-azo dye films and their optical properties for write-once blu-ray recording

A nickel(II)-azo dye was synthesized in order to obtain a suitable optical recording medium for write-once blu-ray recording with low-to-high signal polarity. Smooth thin film of the nickel(II)-azo dye was prepared by spin-coating method. Absorption, reflectance spectra and optical constants (complex refractive indices N=n+ik) of the thin film were investigated in the wavelength region of 300-700 nm. To demonstrate the physical basis of low-to-high polarity, the relationships between the absorption, reflectivity and optical constants for the nickel(II)-azo dye in spin-coated films were discussed. It is found that the thin film has a strong absorption band in the wavelength region of 370-500 nm and a strong absorbance at 405 nm. The reflectance spectra show that a low reflectivity of the unrecorded thin film at 405 nm can be obtained. The thin film of the nickel(II)-azo dye gives a relatively low n value of 1.36 and a relatively high k value of 0.51 at 405 nm. In addition, in order to examine its possible use as a blu-ray recording medium, the spin-coated film of the nickel(II)-azo dye was studied by a static optical recording testing system. The results demonstrate that high reflectivity contrast (85%) with low-to-high polarity can be obtained at an optimum laser writing power and pulse width using the nickel(II)-azo dye thin film as the recording layer. Moreover, the recording marks on the film are clear, circular, regular, and their size is as small as 200 nm or even less. These results indicate that the nickel(II)-azo dye is promising for applications in high-performance write-once blu-ray recording systems at 405 nm.

Third-order nonlinear optical properties and optical limiting property of metallonaphthalocyanine

Optical limiting [OL] property of naphthalocyanine zinc [ZnNc] in DMSO solution was first studied with 30 Ps laser pulses at the wavelength of 532 nm. For comparison, OL measurement of C60 was performed under the same experimental conditions. The results indicate that the optical limiting ability of ZnNc is similar to that of C60. To investigate the mechanism of OL effect, Z-scan measurements were carried out with 30 ps laser pulses at the wavelength of 532 nm, the repetition of 2 Hz. The ZnNc solution sample displays strong reverse saturable absorption effect. The OL effect of ZnNc results from nonlinear absorption, and it can be considered as one of the most promising OL materials.