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The present paper describes a method for decreasing the pit size in optical lithography by using combination of a four-zone annular binary phase filter and the phase transition material. The binary phase filter was designed by vector diffraction theory when linearly polarized light is focused under high numerical aperture objective lens ( NA =0.95), the figures of merit produced by this filter are as follows: comp ared with the diffraction limited spot, Strehl ratio S is 0.254, the spot size in the short axis direction is reduced down to 77.3%, the depth of focus is elongated to 317% for the supe r-resolved spot,. Then a phase transition material is place d in the focal plane of the objective lens, according to the threshold effect of the material, the groove linewidth and pit size can decrease down to about 0.2O , which is about 90nm at the wavelength of 405nm. Therefore, nanoscale phase transition optical lithography is realized, and the capacity and density of the optical memory devices can be increased up to 2-3 times the blu-ray disks. Keywords: phase transition material s lithography, su per-resolving, phase pupil filter

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.

A nickel(II) hydrazone complex was synthesized in order to obtain a suitable optical recording medium for the new generation recordable blu-ray disk. Smooth thin films of the nickel(II) hydrazone complex were prepared by using the spin-coating method. Absorption and reflectance spectra of the thin films were evaluated in the wavelength 300-700 nm. Thermal properties of the nickel(II) complex were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Optical constants (complex refractive indices N=n+ik) and thickness of the thin film, prepared on single-crystal silicon substrate, were investigated on a rotating analyzer-polarizer scanning ellipsometer in the wavelength 285-705 nm. In addition, in order to examine its possible use as a blu-ray recording medium, the spin-coated film of the nickel(II) complex was prepared on K9 glass substrate with a silver reflective layer, and was studied by static optical recording testing system with a 406.7 nm laser. It is found that the absorption spectra of the thin film has an strong absorption band in the wavelength region 360-420 nm and a moderate absorbance at the 405 nm side, which indicates that the absorption of the film is well matched with the laser wavelength of the 405 nm. The reflectance spectra show that a high reflectivity of the thin film at 405 nm wavelength can be obtained by an optimum film thickness and an appropriate metal reflective layer. The thin film of the nickel(II) complex gives a high n value of 1.62 and a low k value of 0.33, corresponding to the wavelength of the blue laser of 405 nm. Measurements of the thermal properties show that the nickel(II) complex holds a high thermal stability (~ 300 °C) and a sharp weight loss which are helpful to fabricate a small and sharp recording mark edge. The results of the static optical recording test, using the nickel(II) complex thin film as the recording layer, demonstrate that high reflectivity contrast (>50 %) can be obtained at an optimum laser writing power and pulse width. In addition, the recording marks are durable even after 20000 times readout. These preliminary results indicate that the nickel(II) hydrazone complex has great potential application for high-density discrecordable system at wavelength of the 405 nm.

Sb-rich SiSb thin film was recently reported as a promising phase change meromy material. In this paper, optical and structural properties of as-deposited amouphous and laser-annealed crystalline Sb-rich SiSb thin films are studied and compared with pure Sb thin film. Sb and Si 15 Sb 85 thin films were deposited on polycarbonate substrates by magnetron sputtering. Laser initialization in pure Sb and Si 15 Sb 85 thin films were performed with phase-change optical disc initializer. Reflectivity Spectrum and XRD analysis were performed on as-deposited and initialized Sb and Si 15 Sb 85 thin films. The influence of Si doping on its optical and structural properties are discussed and qualitatively explained by a distorted structure model. Keywords : Sb, Sb-rich SiSb film, Reflectivity, XRD 1 INTRODUCTION Chalcogenide phase change materials are extensively studied in recent decades [1-4] , for its attractive applications in reversible phase change optical discs and nonvolatile random access memory. Several materials such as GeSbTe

Phase transition kinetics of Sb 2 Te 3 phase change thin films was investigated in this paper. Sb 2 Te 3 thin films, with thickness of ~100nm, were deposited on K9 glass substrates by DC magnetron sputtering with an alloy target. The crystallization kinetics of Sb 2 Te 3 thin films under isothermal and non-isothermal annealing was analyzed by a home-made in situ temperature-dependent reflectivity tester. From the heating rate dependences of phase transition temperatures, the activation energy was derived. The obtained values of the Avrami indexes indicate that a two dimension growth crystallization mechanism is responsible for the amorphous-crystalline transformation of Sb 2 Te 3 phase change thin films. Although phase transition of Sb 2 Te 3 thin film is confirmed to be continuous in a larger temperature range, but short laser pulse can easily trigger its crystallization process and form clear and confined crystalline marks.

Super-resolution near-field structures (super-RENS) with antimony bismuth mask layer (Sb 1-x Bi x , X =0, 0.1, 0.2 and 0.9) were fabricated by magnetron sputtering. AgInSbTe and ZnS-SiO 2 were used as recording layer and dielectric layer respectively. Static recording tests with and without super-RENS were carried out using static recording tester whose laser wavelength is 406.7 and numerical aperture is 0.8. The recorded marks were observed by atomic force microscopy (AFM). The influences of Bi proportion in the films on the super-resolution recording properties were investigated.

Three kinds of novel metal(II)-azo complexes based on indandione were synthesized in order to obtain a suitable optical recording medium for blu-ray disc-recordable (BD-R). Smooth thin films of these metal(II)-azo complexes were prepared by spin-coating method. Absorption spectra, thermal decomposition and blu-ray static recording properties of the thin films were investigated. These metal(II)-azo complexes, with absorption peaks at 435 - 444nm wavelength region, have high thermal stability with sharp thermal decomposition thresholds. The results of the blue-ray (405nm) static optical recording test of these metal(II)-azo complexes indicated that high reflectivity contrast (>50%) can be obtained at appropriate laser power and pulse width, and the size of the recording mark on the Co(II) complex film is as small as 200nm at writing laser power of 2mW and pulse width of 300ns. These results imply that metal(II)-azo complexes based on indandione are promising candidates as recording media of BD-R.

“Glass/SiN(30nm)/SiAg(20nm)/SiN(20nm)/TbFeCo(50nm)/SiN(10nm)”. SiN and TbFeCo films were prepare 2 d by Radio frequency (RF) and Direct current (DC) magnetron sputtering respectively. The SiAg nonmagnetic mask layer was deposited by co-sputtering from a composite target. In the process of sputtering, the substrate negative DC bias voltage was kept at about 100V. Magnetic properties were obtained by vibrating sample magnetometer(VSM) and the magneto optical Kerr measurement. The magnetic recording was conducted by a home-made laser-assisted optic-magnetic hybrid recording setup, whose laser wavelength is 406.7nm and numerical aperture of converging lens is 0.80, respectively. The optical spot size is about 600nm. In the course of recording, the laser pulse was fixed at 100ns, and the magnetic field intensity was 300 Oe. The magnetic domains with a size of about 100nm were obtained, which is about 1/6 of the optical spot size. The analysis indicates that the SiAg nonmagnetic mask layer played a key role in reducing the magnetic domain size.

To break through the diffraction limit by optical super-resolution thin films is very attractive for the applications in optical and photonic devices. Large optical nonlinearities, such as optic-thermal nonlinearity and the third order optical nonlinearity, of optical thin film materials are very critical to super resolution optical storage, imaging, lithography, and the enhancement of the throughput of the optical near-field nano-aperture. The super-resolution effect in optical thin films or film structures under laser irradiation is focused in this paper. And its applications, especially in super high density optical storage are analyzed and discussed.

Effects of dyes and initiators in the photopolymer on the holographic storage properties are studied. Diffraction efficiency of photopolymer with Erythrosin B (ErB) as dye is significantly larger than that the same photopolymer with Eosin Y (EY), Rose Bengal (RsB), Rodamine B (RoB) and Fluorescein (F) as dyes under the same conditions. The maximum absorption of ErB is closer to 514nm than the others, and the photobleaching rate constant of the initiating system is higher than the others. Compared with the holographic properties with triethanolamine(TEA) as initiator, diffraction efficiency of the photopolymer with N-phenylglycine(NPG) as initiator is lower, but the photopolymer shows higher stability.

Crystallization was induced in amorphous Ge 2 Sb 2 Te 5 and AgInSbTe films by femtosecond laser with an average power of 20mW at a frequency of 1 kHz and a pulsed width of 120 fs. Transmission electron microscopy observes the morphology of Ge 2 Sb 2 Te 5 and AgInSbTe films before and after irradiation of femtosecond laser pulses and confirms the existence of crystalline state.

We report a method for testing small light spot produced by an optical system with high numerical-aperture (NA). A high NA objective was used to converge the incident linear polarized light, and a tapered optical fiber probe with an opening of 50-80 nm mounted in the near-field optical microscopy (SNOM) apparatus was used to measure light intensity. The small light spot can be measured with high spatial resolution. The results show that a resolution of 50~100 nm can be obtained.

We designed and built up an apparatus for measuring the properties of magnetic coupling thin films and hybrid recording media. The temperature of the tested points of the thin film samples change as irradiated by focused laser beam through adjusting laser power. By calculation, we also simulated the distribution of temperature in TbFeCo magneto-optical films irradiated by laser, in order to get the relationship between the film coercive force and the irradiating laser power. Using this apparatus, we can determine the Curie temperature and compensation temperature of the films. The apparatus might present an effective approach for studying the variation of magneto-optical characteristics of films at different temperatures and the properties of magnetic coupling multilayer films, and it could be useful for studying hybrid recording.

Super-resolution read-only optical disks using different mask materials and stack structures were prepared by using rf sputtering method, and then dynamic readout properties were measured, our results show that by using Si as the mask material the signal-to-noise ratio can reach about 35dB, and the density can be increased both in the linear direction and in the track direction, while by using AgInSbTe as the mask material the optimum signal-to-noise ratio is about 40dB, which is very close to the practical application level.

Three kinds of novel metallized azo dyes based on 4-methylthiazole, 5-methyl-3-isoxazole and 5-methyl-1,3,4-thiadiazole were synthesized in order to obtain a suitable optical recording medium for digital versatile disc-recordable(DVD-R). The absorption spectra, optical constants and thermal decomposition as well as red-light (650nm) static recording properties of thr ee nickel-azo dye films were investigated . Particularly, the ni ckel-azo dye film based on 5-methyl-1,3,4-thiadiazole, peaking at 554nm and 602nm, with higher refractive index a n=2.41 a and lower extinction coefficient ( k=0.042) at the wavelength 650nm and a sharp threshold of thermal decomposition at 335°C was obtained. The results of the red-light(650nm) static optical reco rding test of this dye film indicated that higher reflectivity contrast of 35% can be obtained at a laser writing power of 7.5mW and pulse width of 200ns. These results imply the nickel-azo dye based on 5-methyl-1,3,4-thiadiazole is a promising candidate as a recording medium of DVD-R. Key words: Metallized azo dye, DVD-R, spectroscopic and th ermal properties, static optical recording

High-density holographic recording parameters changing with the exposure wavelength of a wideband sensitive photopolymer are studied. The results show that the maximum diffraction efficiency, exposure sensitivity, maximum refraction index modulation, dynamic range and the exposure time constant are all incremental with the increase of the exposure wavelength. The analysis indicates that the scattering plays an important role in the phenomenon.

Measurement technology plays an important role in the research of optical storage. Aiming at constructing research platform for blue-ray optical data storage, we designed and built a modularized static testing system, in which laser wavelength is 406.7nm. Modulation/demodulation technique is employed to weaken the test noise. The focus move mode decreases the requirement in size of samples. And Piezoeletronic nano-positioner is used to facilitate the relocation of recording marks and improve test repeatability. Experimental results are also given to verify the performance of the static testing system.

Thin film of a novel charge-transfer complex CuTCNQ derivative was prepared by spin-coating. Experimental results of this film for red-light rewritable optical storage are as follows: writing power13mW, writing pulse duration 200ns; erasing power 3mW, erasing pulse duration1000ns; reflectivity contrast C is greater than or equal to 27%; numbers of write-erase cycle N is greater than or equal to 1000.

High-density Optical storage technology which uses a 405 nm laser and an objective lens of high numerical aperture (NA) of 0.85 is developing rapidly due to its high capacity over 23 GB on a single layer of a 120mm-diameter optical disc and great commercial demands. New storage media have been the bottleneck in high density optical storage. Organic material can be an attractive optical storage medium with various advantages, such as good sensitivity, easy fabrication, reasonable cost and structural flexibility, etc, compared with inorganic storage material. Efforts have been made to seek for new organic storage materials with high performance matching the 405 nm short wavelength laser. In this paper, recent progresses in developing organic materials as recording media for high density blue laser optical storage are presented. The recording mechanism of recordable dye layer and basic requirements for the dye materials are analyzed and discussed.

Static recording characteristics of super-resolution near-field structure with bismuth (Bi) mask layer and antimony (Sb) mask layer were investigated and compared. The experimental results show that Bi mask layer can also concentrate energy into the center of a laser beam at a low laser energy input similar to Sb, which may be because that Bi film exhibits giant nonlinearity at low laser intensity. The direct observation of laser-recording marks may help better understand the working mechanism of the super-RENS, super-resolution ablation, and other nonlinear switching phenomena.

Volume holographic digital data storage has many performance characteristics including large storage capacity and high transfer rate. But there are some problems in the commercial applications for holographic digital disc of volume holographic digital data storage. A single beam setup is introduced in this article for holographic digital disc. In this new system, the reference beam and the information beam are coaxially arranged to perform reading and writing. This new single beam setup can reduce the complexity, the demand for mechanical precision, the size and cost of the conventional holographic digital storage setup using dual beams. And it is also compatible with the conventional optical disk technologies.

A novel metallized azo dye has been synthesized and its thin film on K9 glass has been prepared. The absorption spectra, thermal character and static optical recording properties with Bi mask layer super-resolution near-field structure (Super-RENS) of the dye were investigated. The results show that the dye film has a broad absorbance band in the region of 450-650nm and the maximum absorbance wavelength is located at 603nm, which is red shifted 17nm comparing with that of its chloroform solution, a steep absorbance falling edge in 603-650 is observed. It is found that the new metallized azo dye occupies excellent thermal stability, initiatory decomposition temperature is at 270°C and the mass loss is about 48% in a narrow temperature region (15°C). Static optical recording tests with and without Super-RENS were carried out using a 650nm semiconductor diode laser with recording power of 7mW and laser pulse duration of 200ns. The AFM images show that the diameter of recording mark on the dye film with Bi mask layer is reduced about 42% comparing with that of recording mark on the dye film without super-resolution near-field structure. It is indicate that Bi can well performed as a mask layer of dye recording layer and the metallized azo dye can be a promising candidate for recording medium with super-resolution near-field structure.

According to the change of refractive index of Sb thin film with temperature and the radial distribution of temperature within the spot, we can consider the spot irradiated by a Gaussian beam as a phase-modulated screen. Based on Fresnel-kirchhoff diffraction theory, a Gaussian diffraction model which can compute the intensity from far field has been set up. Using this model we can study the nonlinear change of mask layer samples induced by different reasons. A numerical calculation of the transmittance through an Sb-type super-resolution near-field structure was carried out as an example. The Gaussian diffraction model, which is similar to the far field detection process in the optical disk system, is very useful for analyzing the photothermal-induced local structure change of thin films in phase-change and super-resolution optical disks.

The use of magnetic capping effect can enhance the head sensitivity of the heat assisted magnetic recording (HAMR). The principle of this effect was analyzed theoretically. The GdFeCo film was used as the capping layer and TbFeCo film was used as the recording layer. Through theoretical calculation we found that a large capping field in the same direction with the external field can be generate d at the interface because of the exchange coupling effect, which had increased the effective strength of the extern al field. Thus, the head sensitivity was improved greatly and the data transfer rate could be faster. We expected that this idea can be used to help write the medium with much larger cocervity such as L1 0 FePt. Keywords: Magnetic capping effect, HAMR, head sensitivity 1. INTRODUCTION HAMR has attracted much attention as the next generation magnetic recording technology beyond the thermal decay limit 1, 2 . It is characterized by heat assisted writing and magnetic flux reading. Heating the magnetic media locally with a focused laser can reduce the cocervity ( Hc ); then, medium with an ultra high Hc can be easier to record by conventional magnetic head. There are many materials

Laser induced darkening in two kinds of glasses, the Nd-doped silicate laser glass and type N 31 Nd-doped phosphate laser glass, were studied by exposing the glass samples in 266nm nanosecond UV laser and 800nm IR femtosecond laser. UV laser and IR fs laser induced different types of color centers in silicate glass, while in phosphate glass, UV laser and fs laser generated same type of color center. Possible mechanisms of color center formation were discussed.

This paper gives the overview of developing optical glasses in last century and points out the important role still paid in modern optical and optoelectronic engineering. The emphases in this paper have been laid on photonic glasses including their different functional roles in comparison with optical glasses, importance in exploration of new photonic devices, as well as their new directions of development.

Three-dimensionally manipulated gold nanoparticles were precipitated in silicate glass containing gold ions by irradiation with femtosecond pulsed laser and successive heat treatment. Influence of the heat treatment conditions on the gold nanoparticles precipitation behaviors was investigated. For the tested silicate glass, the treatment temperature threshold of irradiated area for color appearance was obviously lower than that of non-irradiated area. Along with increasing the treatment temperature from such threshold, the irradiated area turned to be colorful. And finally the whole glass became multicolored corresponding to a certain high temperature. Absorption spectrum measurement indicated that, under the given irradiation condition, the sizes of Au nanoparticles were obviously affected by the heat treatment temperature.

The Bi1Dy2Fe4.3Al0.7O12 films with perpendicular anisotropy were successfully prepared by citric acid complex type sol-gel method. The properties of Bi-substituted garnet films annealed at different temperatures were investigated. The results indicated the garnet films had high squareness. The coercive force of the films was about 1100 Oe. The figures of merit of 2° at 430 nm and 1.5° at 520 nm were obtained. The best crystallization temperature was 650°C.

Monolayer TeOx thin films were deposited on K9 glass substrates or copper grids by vacuum evaporation. Structure of the as-deposited TeOx thin film was determined by TEM and XPS. The TeOx thin film was successfully recorded with a short-wavelength laser beam (514.5 nm). Atomic force microscopy (AFM) is used to study the microstructure of recorded marks. Micro-area morphology images show that the marks are deformed, and depressions and bulges have been imaged in the recorded marks. The level of the deformation is enhanced with the increase of writing power. AFM allows a precise determination of the mark size, the depression depth and the bulge height. The present setup allows the identification of individual marks through a specific location method and the correlation of the reflectivity contast, C, caused by a specific writing power to the morphology of the marks. According to the results of TEM analysis, there was no obvious difference between the phase state of as-deposited film and that of the recorded area. Based on the experimental results, the recording mechanism of TeOx thin film was discussed.

Due to germanium doping in the AgInTeSb film, Ag2Te phase was formed at minor doping and disappeared when thegermanium content was high, AgInTe2 phase changed into AgIn2 phase, and Ge2Sb2Te5 new crystalline phase appeared.The crystallization temperature of AglnTeSbGe increased manifestly with Ge addition. A doping amount of 4.1 at. %germanium increases the reflectivity contrast to be greater than 30% almost in the whole visible region.Keywords: Phase-change media, Crystallization, Germanium doping, Reflectivity contrast 1. INTRODUCTION The digital video optical disk recorder has been recently introduced in the market. As a result, a user capacity of morethan 20 GB will be required for the next-generation optical disk to store HDTV moving pictures of duration longer thantwo hours. The data density is usually derived from the amorphous mark size. This means that both targeted radial track pitch and bit length reduction is based on the optical spot size reduction. Reduced spatial dimensions may lead to anenhanced thermal interference in the track and between adjacent tracks. An example is thermal cross-erase, i.e., the(partial) recrystallization of amorphous marks in the adjacent track during the write process. In order to improve the

Organometallic photochromic complexes, which are more stable than those traditional pure organic photochromic compounds, have a wide variety of potential applications in high-density optical storage. In this paper, Ag-TCNQ and Cu-TCNQ thin films were prepared by physical vapor deposition method. The proportion dependence of the spectral and optical properties of Ag-TCNQ thin films were studied and discussed. Multilayer film configuration was designed and prepared for optical memory study and its short-wavelength (514.5 nm) photochromic characteristics were reported. A recommendation of application of Metal TCNQ complexes for high-density and super high density optical storage was proposed as well.

Subphthalocyanine (SubPc) thin films exhibit attractive characteristics in high-density optical storage applications. We have realized red-light (632.8 nm) recording on SubPc thin films previously. In this paper, novel subphthalocyanine thin films were developed by vacuum evaporation and spin-coating method. Their static and dynamic green-light (514.5 nm) recording performance were studied using self-developed short-wavelength optical disk testers. Sufficient reflectivity, reflectivity contrast and CNR can also be obtained at 514.5 nm if an appropriate multilayer structure was applied. It spread the dyes' traditional operating wavelength and provided a new clew for double-wavelength (even double short-wavelength) recording/reading and choosing short-wavelength recording materials.

Great progress in optical storage has taken place in the last decade. The development of optical discs is always towards higher and higher storage density and data transfer rate in order to meet the ever-increasing requirements of applications in audio, video and image areas. It has been proved a logical and effective approach to employ laser light of shorter wavelength and lenses of higher numerical aperture for increasing storage density, as is shown by the evolution of optical disc from CD family to DVD family. At present, research and development of high density DVD (HD-DVD), blu-ray disc and advanced storage magneto-optical (AS-MO) disc are carried out very extensively. Meanwhile, miniaturization of disc size and use of multiplication techniques to increase the storage density and capacity have already given rise to new formats such as iD Photo disc and Data Play disc as well as multi-layer discs. Digital holographic storage (DHS) disc is also one of the research and development subjects of many companies and research institutions. Some new concept optical storage such as fluorescent multiplayer disc (FMD) is also under intensive development. All these have greatly promoted applications of optical discs in audio, video and image devices.

The relationships among the recording laser power, laser pulse width, and the recording properties of Ag5In5Sb47Te33 thin films were investigated, and the morphology of the recording domains were directly observed by using the homemade apparatus. The results show that the clear and high reflectivity contrast recording domains can be obtained when the laser energy is in a certain range. By optimizing the recording condition, the recording domains with a diameter of 380 to 400 nm and reflectivity contrast of 22% are obtained under the recording power of 12 mW and pulse width of 90 ns.

By using Si thin film to replace the Al reflective layer in conventional ROM, the recording pits with a diameter of 380 nm and a depth of 50 nm are read out on the dynamic measuring equipment with a laser wavelength λ of 632.8 nm and a NA of 0.40. In the course of reproduction, the readout power is optimized, and the velocity is 5 m/s. The optimum Si thin film thickness is 25 nm and the CNR is 35 dB.

Optical and morphological properties induced by laser irradiation in oxotitanium phthalocyanine (TiOPc) film were investigated at 650 nm wavelength with semiconductor laser. The reversible changes of spectra in the region of 610 - 730 nm wavelength were observed. The varieties of refractive index and extinction coefficient of the film before and after laser irradiation were detected. The morphological structure was investigated with transmission electron microscope (TEM) as well. The results suggest that the changes of the film optical properties are induced by photo-thermal processes, and this characteristic is significant to phthalocyanine film as promising candidate for DVD-rewritable recording medium (DVD-RW).

Nickel phthalocyanine thin film was prepared by vacuum deposition, the absorption and transmission spectra, the thermal stability of the film were reported. And the static optical recording properties of the thin film were investigated with a self-developed short-wavelength optical tester with high NA objective lens. The results show that this film occupied suitable absorption and transmission properties for short-wavelength (514.5 nm) optical recording, excellent thermal stability and outstanding thermal decomposition characteristics. And high reflectivity contrast was obtained at low writing power and short writing pulse width using the Ar + laser (514.5 nm) irradiation. The results indicate that metal phthalocyanine is not only qualified for traditional near infrared optical recording medium of CD-R, but also a promising candidate for the recording medium of green-light DVD-R.

ASM method is an effective method for disk-type photopolymer high-density holographic storage that has a limited medium thickness. In this paper, the effects of recording angles of ASM method disk-type photopolymer high-density holographic storage on the recording capacity and density are studied theoretically. The calculation and analysis show that the recording density and capacity depend on the recording angles critically whether the spherical wave beam or plane wave beam is used as the reference beam. The results show that no matter spherical wave or plane wave is used as the reference beam the recording density and capacity increases monotonously with the increase of θ s when θ R is fixed. When the recording angle between two recording beams is large, it has an optimal incidence angle of reference beam to get the maximum recording density and capacity. By using this optimal recording angle we can get 3 - 4 times improvmeent of recording density and capacity.

A new azo metal chelate thin film has been developed for digital versatile disk recordable (DVD-R) by means of a spin-coating. The absorption of the film matches very well with the wavelength of the GaAlInP semiconductor diode laser (0.63 approximately 0.65 μm). Thermal property of azo metal chelate indicates that the rapid decomposition of the dye happens in the narrow temperature zone. The optical recording performance of the azo nickel chelate thin film shows that high reflectivity contrast (34%) can be obtained at low writing power and short writing pulse-width using He-Ne laser (632.8 nm) irradiation. The average jitter of 5-in DVD-R disk after recorded with optimistic power on DVD-RT650 tester is less than 12%.

Green light sensitive acrylamide-based photopolymer system has been prepared. The photosensitive medium was composed of monomer, photoinitiator, charge transfer agents and polymeric film-forming binder. The best Eosin Y, TEA, BAA and AA's concentration were got by optimization of acrylamide-based photopolymers composition. And diffraction efficiency as high as 55% with energetic sensitivity of 60 mJ/cm2 has been obtained in the photosensitive films of 150 μm thickness. The principle of photopolymerization reaction was investigated in the paper, especially the function of charge transfer agents TEA and DPI were studied and we found that there existed a compensation effect between TEA and DPI in the polymerization process of photopolymer.

The conventional TbFeCo magneto-optical medium has a relatively smaller kerr rotation angle in blue region than in the red. Consequently, intensive optimization of the RE-TM blue disk is needed. In this paper, optimization of magneto-optical properties and optical properties was carried out, and good results were obtained. We also calculated the temperature distribution of the recording layer, the results showed that the newly designed structure was successful in temperature controlling and had better thermal response.

In this paper, spin-coated thin films of phthalocyanine dye were prepared. Absorption spectrum of the thin film shows a comparatively broad absorption at the wavelength region 630 - 770 nm and there is a steep absorption edge at the wavelength 750 nm, which is crucial to high reflectivity. Optical parameters of the thin film was measured by a spectroscopic ellipsometer. Extinction coefficient found to be very little at the wavelength 780 - 810 nm. 5-in CD-R discs made of this dye exhibit good performance after recorded in Yamaha 20 speed recorder. Jitters of land or pit are less than 35 ns and the 3T-11T's signals show very good quality. This dye is promising recording media for CD-R for much higher speed recording in the future.

Metallized azo dyes are paid much attention as recording media of digital versatile disc-recordable (DVD-R) due to their excellent optical and thermal properties within short wavelength (630 to approximately 650 nm). In this paper, a novel metallized azo dye has been synthesized. Smooth films on optical glass and single-crystal silicon were prepared by spin-coating method. The UV-Vis absorption spectra of the dye were measured in solution and in film. The optical constants (complex refractive index N=n+\ik) of the film on single-crystal silicon have been determined using scanning ellipsometer. The variation of the complex refractive index N with wavelength λ was obtained. Thermo-gravimetric analysis (TGA) of the dye showed clear threshold of thermal decomposition. Static optical recording tests were carried out to evaluate the performance of the optical recording medium. The results show that the dye is a promising candidate as a recording medium of DVD-R.

The relationship of Bragg-mismatch and recording angles of holographic photopolymer was deduced, the calculated and experimental results were compared. It showed that the theory tallied with the experiment well. The result indicates that the Bragg-mismatch depends on the recording angles strongly, this result is important to the design of high-density photopolymer holographic memory system.

In this paper, the optical properties induced by laser irradiation in managanese phthalocyanine [Mn(OH)Pc] thin film were investigated with the Ar+ laser (514.5 nm) irradiation. The reversible changes of spectra in the region of 630 - 750 nm were observed. The refractive index and extinction coefficient before and after laser irradiation were determined. The results imply that the changes of the film optical properties are induced by photo-thermal processes, and this characteristic is significant to phthalocyanine film as promising candidate for DVD-rewritable recording medium (DVD-RW).

A new azo nickel chelate thin film has been developed for short wavelength write-once optical recording by a spin-coating process. Thermal property of the dye was studied by thermo-gravimetric analyzer (TGA). The azo nickel chelate begins to decompose at temperature 295.6°C, which is 44°C above that of azo, and rapidly decomposes in the narrow temperature range. A dynamic optical recording test on the disc made of this dye indicated that the CNR of written signals was more than 43dB at low writing power and short writing pulse-width using Ar+ laser (514 nm) irradiation in a wide scan velocity range.

The optical constants of each layer in the optical disk are assumed to be constant regardless of film thickness in conventional optical design and optimization of the multilayer structures. However, this assumption is not valid when the layer becomes very thin for its discontinuity. As we know, very thin layers (< 50 nm) are included in the high-density and super-high density optical disks, such as DVD-RAM, high-density DVD (HD-DVD), and super-resolution near-field structure (Super-RENS). In this paper, the thickness error sensitivity factor for dielectric optical multilayer was derived from the optical matrix, and the change of optical constant of the very thin layers with the film thickness variation is analyzed at the same time. The effect of the thickness error and corresponding refractive index change on the reflectivity or reflectivity contrast of the optical disk multilayer was analyzed with a numerical calculation. As an example, we made a structure optimization for the 4-layer DVD-RAM systems with GeSbTe and AgInSbTe phase-change materials as recording media. These results are significant in improving the accuracy of optical design and thermal simlation of high density and super-high density optical disks.

We introduce a homemade testing system for groove geometry of CD-R substrates by measuring diffraction orders. This testing is of particular importance in CD-R disc manufacture process because the results fed back from the testing can be used to help optimizing recording, developing, metalizing, electroplating and replicating processes. Even if the width and depth of groove are not accurately obtained by this system, it is also valuable in CD-R disc manufacturing process because the system is simple, sensitive, quick and non- destructive, and can be well-used to judge the quality of substrates. The results of the same sample tested by our system and an AFM microscope are presented.

This paper gives a review of the new progress in the super high-density optical storage research in China. The main research fields are short wavelength optical disk storage, near field optical storage, digital holographic storage and photo-induced multi dimensional storage. General remarks of the super high-density optical storage research are also given.