BiOx films are prepared by reactive direct current (DC) magnetron sputtering from a metallic bismuth target in Ar + O2 with different O2/Ar ratios. It is found that the optical property of BiOx films is sensitive to O2/Ar ratios and the films deposited at O2/Ar ratio of 0.5 have the best reflectivity contrast under the same conditions. The structure and optical characteristics of the films are studied by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and spectrophotometer. As revealed by investigations, the phase transition is mainly responsible for the change of optical properties. The static test results indicate that the BiOx films have good writing sensitivity for blue laser beams. A high reflectivity contrast of about 52% at a writing power of 11 mW and writing pulse width of 800 ns is obtained. In addition, the films demonstrate good stability after being read for 10000 times.

The influence of oxygen partial pressure on the optical properties of NiOx thin films deposited by reactive DC-magnetron sputtering from a nickel metal target in a mixture gas of oxygen and argon was presented. With the oxygen ratio increasing, the reflectivity of the as-deposited films decreased, and optical band gap increased. Thermogravimetric analysis (TGA) showed that the decompose temperature of the films was above 250 Celsius degrees. After annealed at 400 Celsius degrees, only films deposited at 5% O2/Ar ratio showed high optical contrast which was about 52%. Scanning electron microscope (SEM) results revealed that the changes of surface morphology were responsible for the optical property variations of the films after annealing. Its thermal stability and high optical contrast before and after annealing made it a good potential write-once optical recording medium.

A novel symmetrical charge transfer fluorene-based compound 2,7-bis (4-methoxystyryl)-9, 9-bis (2-ethylhexyl)-9H-fluorene (abbreviated as BMOSF) was synthesized and its nonlinear absorption was investigated using two different laser systems: a 140-fs, 800-nm Ti:sapphire laser operating at 1-kHz repetition rate and a 38-ps, 1064-nm Nd:YAG pulsed laser operating at 10-Hz repetition rate, respectively. Unique nonlinear absorption properties in this new compound were observed that rise from multiphoton absorption. The nonlinear absorption coefficients were measured to be 6.02*10^(-3) cm/GW (due to two-photon absorption, exciting wavelength is 800 nm) and 3.6*10^(-20) cm3/W2 (due to three-photon absorption, exciting wavelength is 1064 nm). This new compound possesses strong fluorescence induced by two-photon absorption and obvious three-photon absorption optical limiting effects.

Crystallization is induced by pulsed laser irradiation of as-deposited amorphous Ge2Sb2Te5 films. Changes of the irradiated areas have been analyzed with the reflectivity contrast. As laser fluences increasing, the reflectivity contrast increases from 0%-2% to 14%-16%, which indicates the structure of as-deposited films transforms from amorphous to crystalline phases. The process of crystallization driven by the movement and rearrangement of atoms is described. And also the influence of the pulse duration on the threshold of crystallization is discussed, the results show that a lower threshold of crystallization can be produced for as-deposited films irradiated by the laser with short pulse duration. However, by the laser with long pulse duration, crystallization can only be formed with a higher threshold. The crystallization of films by irradiation of laser pulses is studied by Raman spectra.

In this paper, the spin-coated thin films of phthalocyanine dye are presented. Absorption spectrum of the thin film shows a comparatively broad absorption in the wavelength range 630-770 nm. Optical parameters of the thin film were measured by a spectroscopic ellipsometer system. 5-in CD-R discs made of this dye exhibit good performance with Yamaha 20-speed recorder. Jitters of land and pit are less than 30 ns, and the 3T-11T's signals show very good quality. This dye is a promising recording medium for CD-R with much higher recording speed.