Abstract: At least one information layer including a recording layer contains a material that can exhibit a transition between two optically different states in response to irradiation with a laser beam as a main component is provided on a substrate, and the material is configured so as to exhibit an energy gap ranging from 0.9 eV to 2.0 eV in the amorphous state. The information layer is configured to have a light transmittance of not less than 30% when irradiated with a laser beam having a wavelength ranging from 300 nm to 450 nm. It is possible to achieve excellent recording/reproduction, even if a plurality of recording layers are provided in the recording medium, when this medium is irradiated with a laser beam with a wavelength in the foregoing range from one side of the medium.

Abstract: An optical information recording medium of the present invention includes at least one information layer. The information layer includes a first protective film, a first interface film, a recording film having the optical characteristics that are changed reversibly by laser beam irradiation, a second interface film, a second protective film, and a reflective film, present in the indicated order from the laser beam incident side. The first interface film includes an oxide of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si. The second interface film includes carbon or a carbide of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and Si.

Abstract: An optical information recording medium comprising a substrate, recording layer and reflecting layer, characterized in that a layer containing a mixture of carbide and oxide is disposed over a surface of the reflecting layer which faces to the recording layer. The carbide is a carbide of at least one metal selected from Ti, Zr, V, Nb, Ta, Cr, Mo and W, and the oxide is an oxide of at least one metal selected from Ti, Zr, V, Nb, Ta, Cr, Mo and W.

Abstract: An optical recording medium simultaneously having higher recording characteristics and storage stability than ever, is obtained. An optical recording medium comprising at least a phase change recording layer, a first diffusion preventing layer, a second diffusion preventing layer and a protective layer formed in this order on a substrate, characterized in that the first diffusion preventing layer and the second diffusion preventing layer comprise a non-gas element and nitrogen and/or oxygen as the main components, the non-gas element in each of the first diffusion preventing layer and the second diffusion preventing layer, is the same, and the content (atomic %) of nitrogen and/or oxygen contained in the second diffusion preventing layer, is larger than the content (atomic %) of nitrogen and/or oxygen contained in the first diffusion preventing layer.

Abstract: An optical recording medium having a phase transition material film and a method of manufacturing the optical recording medium are provided. In the method, first, a phase transition material film, a sacrificial film, and a metal film are sequentially stacked on a substrate. Next, the metal film is anodized to form a metal oxide film having a plurality of holes, and portions of the sacrificial film exposed through the holes are anode-oxidized to form oxide films. Thereafter, the phase transition material film is patterned by removing the metal oxide film and by etching the sacrificial film and the phase transition material film using the oxide films as a mask. Then, the oxide films are removed from the sacrificial film, and an upper insulation film, a reflection film, and a protection film are deposited on the upper surface of the patterned phase transition material film.

Abstract: To obtain an optical recording medium capable of recording at various recording transfer rates from a low speed to a high speed, by using a simple recording strategy. A recording layer 18 of a write-once optical recording medium capable of recording from a low speed to a high speed is formed by laminating a first sub recording layer 18A and a second sub recording layer 18B each containing a metal as its main component. When the recording layer (laminated recording layer) 18 is irradiated with a laser beam having a wavelength equal to or shorter than a blue wavelength by using a recording strategy comprising only a ratio of write power to bias power, the main component metals contained in the first and second sub recording layers 18A, 18B diffuse and are thus mixed together, forming the sub recording layers into a single layer by means of such mixing and forming recording marks whose reflectance have been irreversibly changed.

Abstract: An information recording medium includes a transparent substrate and a recording layer or a metal layer provided on the transparent substrate directly or via a ground layer. The information recording medium has a RAM area on which information is recorded, reproduced or erased, and a ROM area from which only reproduction is made, and an average thickness of the recording layer of said RAM area is larger than that of the recording layer or metal layer of the ROM area.

Abstract: An optical recording medium includes a support substrate, a first resin layer and a second resin layer formed on opposite surface sides of the support substrate, an information recording layer formed between the first resin layer and the support substrate and containing a recording film, and a moisture-proof layer formed between the second resin layer and the support substrate and the moisture-proof layer contains at least one element among elements contained in the recording film.

Abstract: A phase change optical recording medium having a wide recording power margin and excellent durability to repetitive recording is disclosed. The medium includes a first protective layer, a recording layer, an interface layer, a second protective layer, and a reflective layer, the layers disposed on a transparent substrate, wherein the interface layer includes a mixture of ZrO2. Preferably, the medium further includes a second interface layer including the mixture of ZrO2 between the first protective layer and the recording layer. In another preferable aspect, the mixture of ZrO2 is represented by the following formula: [(ZrO2)100-?(X)?]?(Z)?(ZnS)? wherein “X” represents an oxide selected from MgO, CaO, Sc2O3, Y2O3, and CeO2; “Z” represents an oxide selected from TiO2, SiO2, Al2O3, MgO, Ta2O5, and ZnO; “?” is 2-15 mol %; “?” is 40-100 mol %; “?” is 0-60 mol %; “?” is 0-60 mol %; and ?+?+?=100 mol %.

Abstract: A recording medium which has, formed on a substrate, a recording layer that contains spherical grains having a substantially uniform grain size and including inorganic grains. Preferably, an undercoat layer having no substantial information recording ability is formed between the substrate and the recording layer.

Abstract: An optical information recording medium of the present invention includes a protective layer; an interface layer; and a recording layer, the optical characteristics of which are changed reversibly when irradiated by a laser beam, layered in this order on a substrate. The protective layer contains at least Zn, S, and Si atoms, and an atomic composition ratio of O to Si is at least 0 and smaller than 2. A refractive index of the interface layer is smaller than a refractive index of the protective layer.

Abstract: An optical recording medium includes a recording layer containing as a primary component an alloy containing at least two elements selected from the group consisting of Fe, Al and Si and the alloy contained in the recording layer as a primary component has a composition [x1, y1, z1] in terms of the ternary composition diagram that falls within a region of a pentagon defined by straight lines connecting points [57, 43, 0], [0, 55, 45], [15, 0, 85], [89, 11, 0] and [0, 16, 84] in the ternary composition diagram. According to the thus configured optical recording medium, only minimal load is placed on the global environment.

Abstract: It is an object of the present invention to provide an optical recording medium wherein hardness of the surface on the incident-light side is high and warping of the optical recording medium is suppressed. The optical recording medium according to the present invention comprises a substrate 11, a recording layer 14 provided upon the substrate 11, a light transmission layer 16 made of ultraviolet curable resin provided upon the functional layer 16, and a hard-coat layer 17 provided upon the light transmission layer 16, wherein the thickness of the light transmission layer 16 is 50 ?m or greater and its pencil hardness is HB or less. Thereby, warping of the optical recording medium arising due to cure shrinkage of the ultraviolet curable resin making up the light transmission layer 16 can be effectively suppressed. Moreover, the hard-coat layer 17 is provided upon this light transmission layer 16, so the occurrence of scratches on the surface of the optical recording medium can be effectively prevented.

Abstract: An optical disk substrate with a central hole is disclosed in the invention. The optical disk substrate includes: a first annular area for clamping, which surrounds the outer edge of the central hole and includes a first upper surface and a first lower surface thereon; and a second annular area for forming an information storing area, which surrounds the outer edge of the first annular area and includes a second upper surface and a second lower surface thereon; besides, the first lower surface and the second lower surface are on the same plane, whereas the first upper surface is higher than the second upper surface. Moreover, an optical disk that applies the optical disk substrate and a method for forming the optical disk are also disclosed in the invention.

Abstract: The optical recording medium of the invention comprises a recording layer and at least one mixed dielectric layer. The mixed dielectric layer contains cerium oxide and an additive compound. The additive compound is at least one compound selected from among aluminum oxide, chromium oxide, iron oxide, manganese oxide, niobium oxide, magnesium oxide, zinc oxide, titanium oxide, yttrium oxide, tantalum oxide, antimony oxide, zirconium oxide, bismuth oxide and magnesium fluoride. The optical recording medium has a high storage reliability and satisfactory recording/reading characteristics.

Abstract: A silver-based alloy thin film is provided for the highly reflective or the semi-reflective layer of optical discs. Alloy additions to silver include gold, rhodium, ruthenium, osmium, platinum, palladium, copper, silicon, cadmium, tin, lithium, nickel, cobalt, manganese, indium, chromium, antimony, gallium, boron, molybdenum, zirconium, beryllium, titanium, aluminum, germanium and zinc. These alloys have moderate to high reflectivity and reasonable corrosion resistance in ambient environments.

Abstract: An optical data storage device for multi-level recording having: a substrate, and a phase change memory medium supported by the substrate. The phase change memory medium preferably has an alloy with a eutectic crystallization base component and at least one element for enhanced sigma-to-dynamic range. The multi-level data storage device is preferably an optical disk with a single layer of memory material for providing multi-level recording with a sigma-to-dynamic range of less than 2%. The phase change recording alloy is preferably an In:Sb:Te material. Preferably, Sb:Te is present at a ratio at, or near, the eutectic point when combined with 30% or less In. A preferred phase change memory material includes an alloy defined by the formula: Inx(SbnTe100-n)100-x where x is 3-30, and n is 63-82.

Abstract: An initiation-free super-resolution optical medium. The optical medium includes, in sequence, a substrate with a first dielectric layer thereon, an active layer on the first dielectric layer to absorb laser beam, a second dielectric layer on the active layer, an initiation-free recording layer on the second dielectric layer, and a third dielectric layer on the initiation-free recording layer.

Abstract: An optical information recording medium having two or more information layers, wherein the irradiation of either the information layer with a laser beam converging thereon causes information signals to be recorded or reproduced; the nearer positioned information layer than the farthest information layer as viewed from the incidence side of the laser beam has a recording layer varying between two optically detectable states, and 0?|Tc?Ta|/Tc?0.1 where Tc is the transmittance of the nearer positioned information layer when the recording layer is in state (a) and Ta, the transmittance, when it is in state (b). This makes possible accurate accurately recording and reproduction of information onto and out of the farther information layer irrespective of whether or not any information is recorded on the nearer information layer.

Abstract: An information recording medium includes a first information layer and a second information layer. The first information layer includes a first recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by irradiation of a laser beam or application of current. The second information layer includes a second recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by the irradiation of the laser beam or the application of the current. The first recording layer is made of a first material, the second recording layer is made of a second material, and the first material is different from the second material.

Abstract: An optical information recording medium of the present invention includes: a substrate with at least one selected from the group consisting of a groove and a pit formed on one surface thereof; at least one information layer provided on the surfaces of the substrate, the information layer including at least one selected from the group consisting of a recording film and a reflective film; a resin layer provided on the information layer; and a light transmission layer provided on the resin layer. The resin layer includes a first resin film and a second resin film disposed in this order from the side of the light transmission layer, and when a water absorption rate of the first resin film is represented by A1 and a water absorption rate of the second resin film is represented by A2, A1 and A2 satisfy: A1>A2. The first resin film and the second resin film may have a different flexural modulus of elasticity.

Abstract: An optical recording medium including a recording layer which includes a reversible phase-change recording material, the recording layer being capable of writing information therein, reading written information therefrom, and rewriting written information by utilizing the reversible phase change of the phase-change recording material, wherein when a recording mark formed in the recording layer is repeatedly read 5000 times, using a continuous wave laser beam having such an intensity Pr that satisfies the condition of 1.1?R?2.0, in which R is ?repeat/?1 as defined in the specification, the optical recording medium satisfies a relationship of d1>dow as defined in the specification. The phase-change recording material, a method of producing the optical recording medium, and a method of writing information in the optical recording medium, reading written information therefrom and rewriting written information therein are proposed.

Abstract: An optical recording medium has a phase-change recording layer containing Sb and Te as essential elements therefor, to which is added at least one element selected from the group consisting of Ag, Au, Cu, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, N, P, Bi, La, Ce, Gd, and Tb, the recording layer being capable of assuming an amorphous phase changed from a crystalline phase by the application of a laser beam thereto, thereby optically recording information. Recording marks are formed in the recording medium by converting a light emission wave of laser beam into a recording pulse train comprising a plurality of on-pulses and off-pulses, with a recording frequency being continuously changed corresponding to the location of each of the recording marks in the radial direction of said recording medium. A recording apparatus has laser beam driving circuit means, signal generation means, and signal transmission means for achieving the above recording method.

Abstract: An information recording medium ensures high reliability and favorable overwrite cycle-ability even when an interface layer is not provided between a recording layer and a dielectric layer. The recording layer and the dielectric layers are formed on the surface of the substrate. In the recording layer, a phase change is generated between a crystal phase and an amorphous phase by irradiation of light or application of electric energy. The dielectric layers are oxide-fluoride-based material layers containing one or more oxides which each are an oxide of at least one element selected from a first group including only Ti, Zr, Cr, Hf, Nb, Ta, Cr and Si and one or more fluorides which each are a fluoride of at least one element selected from a second group including only La, Ce, Pr, Nd, Gd, Dy, Ho, Er and Yb.

Abstract: A description is given of multi-stack optical data storage medium (20) for rewritable recording by means of a focused laser-light beam (30), said medium (20) having a substrate (1) with deposited on a side thereof: a first recording slick (2) comprising a phase-change type recording layer (6)- at least one further recording stack (3) comprising a phase-change type recording layer (12),- a transparent spacer layer (9) adjacent each further recording stack (3). The further recording stack (3) is sufficiently transmissive to ensure proper sensitivity for reading and recording in the first recording stack (2). For this purpose, at least one heat sink layer (10) made of HfNx, and 1.1=×=1.6, is present in at least one of the recording stacks (3). The heat sink layer (10) further ensure proper cooling behavior of the recording layer (12) of the further recording stack (3) in order to obtain sufficient recording performance in the further recording stack (3).

Abstract: An information recording medium having such a recording material layer on a substrate where reversible phase change between electrically or optically detectable states can be caused by electric energy or electromagnetic energy. The recording material forming the recording layer is either a material having a crystal structure including lattice defects in one phase of the reversible phase change or a material having a complex phase composed of a crystal portion including a lattice defect in one phase of the reversible phase change and an amorphous portion. Both portions contain a common element. A part of the lattice defects are filled with an element other than the element constituting the crystal structure. The recording medium having a recording thin film exhibits little variation of the recording and reproduction characteristics even after repetition of recording and reproduction, excellent weatherability, strong resistance against composition variation, and easily controllable characteristics.

Abstract: An information recording medium which ensures high reliability and favorable overwrite cycle-ability is provided, even when an interface layer is not provided between a recording layer and a dielectric layer. The recording layer 4 and the dielectric layers 2 and 6 are formed on the surface of the substrate 1. In the recording layer 4, a phase change is generated between a crystal phase and an amorphous phase by irradiation of light or application of an electric energy. The dielectric layers 2 and 6 are Zr/Hf—Cr—O-based material layers comprising at least one of Zr and Hf, Cr and O, preferably consisting essentially of material expressed, for example, with the formula (MO2)N(Cr2O3)100?N (mol %) wherein M is either or both of Zr and Hf, and 20?N?80.

Abstract: A phase-change optical recording medium which attains a high erasability in overwriting at a high linear velocity and has high recording sensitivity, excellent OW cycling characteristics, and excellent weatherability. The phase-change optical recording medium comprises a substrate and formed thereon a multilayered film comprising a protective layer and a recording layer and is that information is recorded/erased based on reversible phase changes in the recording layer between a crystalline phase and an amorphous phase, wherein the protective layer is a film made of an oxide of tantalum or aluminum and at least one carbide, and the content of the carbide is from 1 to 40 mol %.

Abstract: An optical information recording medium according to the present invention includes at least one information layer in which a first dielectric film that contains Cr, O and at least one element (M1) selected from Zr and Hf, a recording film that is provided on the first dielectric film and changed in optical property reversibly by irradiation of laser beams, and a second dielectric film that is provided on the recording film and contains Cr, O and the at least one element (M1) selected from Zr and Hf, are provided in this order from a side on which laser beams are incident. The first dielectric film has a Cr atom concentration of at least 6 at %, the second dielectric film has a Cr atom concentration of at least 9 at %, and the Cr atom concentration of the second dielectric film is larger than the Cr atom concentration of the first dielectric film.

Abstract: An object of the present invention is to provide a phase-change optical recording medium of an amorphous recording mark type. The optical recording medium is a write once type medium capable of decreasing the degradation of an information signal which has been already recorded. The recording layer of the optical recording medium according to the present invention includes a first recording layer and a second recording layer. The first recording layer comprises a first composition which can be changed into another composition more stable in an amorphous state by combining with a component included in the second recording layer.

Abstract: A phase change optical disc that has a multilayer structure. The structure is sequentially laminated on the transparent substrate starting with a first dielectric layer; a phase control layer, the phase control layer having two areas are defined in a laser spot in which the irradiation with a reproduction beam causes a phase difference that alters the optical path of the reflected reproduction beam passing through the areas; a second dielectric layer; the phase change recording layer, which reversibly converts between a crystal phase and an amorphous phase by irradiation with a recording beam; a third dielectric layer; a reflective layer; and a protective layer. An alternative embodiment includes a fourth dielectric layer disposed between the reflective layer and the protective layer. The information of a recording mark can be accurately reproduced due to the phase difference between adjacent areas on the phase control layer, thereby reducing the size of the effective spot of the reproduction beam.

Abstract: The present invention provides CD-RW which makes high velocity recording at a level of at least 24-times velocity possible, rewritable DVD which makes high velocity recording at a level of at least 6-times velocity possible, and a recording method therefor, while maintaining interchangeability with conventional CD-RW standards and rewritable DVD standards.

Abstract: A phase-change optical information recording medium in which information can be recorded, reproduced and rewritten and which includes a first transparent substrate having a wobbling guide groove which is spirally formed thereon at a pitch; a first dielectric layer located overlying the first transparent substrate and having an optical thickness of from 80 nm to 200 nm; a phase-change recording layer located overlying the first dielectric layer and having an optical thickness of from 20 to 50 nm when the recording layer is in an erased state; a second dielectric layer located overlying the recording layer and having an optical thickness of from 10 nm to 70 nm; a reflection layer located overlying the second dielectric layer; optionally a third dielectric layer located between the second dielectric layer and the reflection layer; and a second transparent substrate located overlying the reflection layer.

Abstract: A film constitution in an optical recording medium including a light incident side substrate and a light reflecting side substrate cooperatively acting as a base of the medium, and includes, between these substrates, those layers formed by sputtering so as to constitute a laminated structure, which layers include: a phase-change recording layer to be phase-changed between an amorphous phase and a crystal phase by laser light irradiation; a first dielectric layer and a second dielectric layer, each having a protective function and an optical adjusting function for the phase-change recording layer; a reflecting film layer for reflecting the laser light transmitted through the phase-change recording layer; a hardness enhancing layer for enhancing the mechanical strength of the medium; and a protecting layer having a function for reducing thermal damages to the light incident side substrate and an optical adjusting function.

Abstract: The information recording medium accosting to the preferred embodiment of the present invention achieves high-speed, high-density recording. The layer, in which ultra-particles made from an optical absorption metal, dielectric, or recording material are formed into regular arrays, is deposited. Resonant Plasmon excitation and resonance absorption of ultra-particles enable the edges of the recorded marks to be identified clearly and intense absorption to occur only in the given layer depending on the wavelength in the case of the multi-layer medium achieving high-density, large-capacity recording.

Abstract: An optical disc has a support base and at least one information-retrieval layer formed over the support base. The information-retrieval layer is transparent and thinner than the support base. The information-retrieval layer exhibits variation in birefringence within ±20 nmpp (nano meter peak to peak) under double-pass measurements during one rotation of the optical disc.

Abstract: An optical information recording medium having a multilayer structure comprising at least a lower protective layer, a phase-change type optical recording layer, an upper protective layer and a reflective layer, on a substrate, wherein the phase-change type optical recording layer has a composition of Zn&ggr;1In&dgr;1Sb&zgr;1Te&ohgr;1, where 0.01≦&ggr;1≦0.1, 0.03≦&dgr;1≦0.08, 0.5≦&zgr;1≦0.7, 0.25≦&ohgr;1≦0.4, and &ggr;1+&dgr;1+&zgr;1+&ohgr;1=1, whereby overwrite recording is carried out by modulation of light intensity of at least strong and weak two levels, so that a crystalline state is an unrecorded state, and an amorphous state is a recorded state.

Abstract: In an optical disk for high density recording, for preventing the deformation of recording tracks caused by stress which may develop between the substrate and the recording stacked film formed thereon, a stress-compensation layer having a metal element such as Ti or Cr as a main component is provided. The stress-compensation layer undergoes contraction (tensile stress) to compensate for compression stress which develops in the stacked film during cooling after the thermal expansion of the substrate surface that occurs at the end of film formation. The stress-compensation layer has a pillar-like structure which, starting from the lower face, reaches the upper face of the film.

Abstract: There is provided an optical recording medium capable of preventing cross erase and increasing its recording density. The optical recording medium includes: a reflecting film; a first transparent film provided on the reflecting film; a first semitransparent film provided on the first transparent film; a second transparent film provided on the first semitransparent film; a recording film provided on the second transparent film, the recording film being capable of reversibly changing an atomic arrangement; and a third transparent film provided on the recording film. The first semitransparent film has a complex refractive index of n−k satisfying relationships of 0<n<1 and 1<k, and a product of a thickness d (nm) of the first semitransparent film and an extinction coefficient k of the complex refractive index is d×k≦44.

Abstract: An optical recording medium includes a recording layer, a first dielectric layer disposed on the side of a light incidence plane through which the laser beam enters with respect to the recording layer, a second dielectric layer disposed on the side opposite to the light incidence plane with respect to the recording layer, a heat radiation layer disposed on the side of the light incidence plane with respect to the first dielectric layer and a reflective layer disposed on the side opposite to the light incidence plane with respect to the second dielectric layer, the recording layer containing a phase change material represented by an atomic composition formula: SbaTebGecMnd, where a is equal to or larger than 57 and equal to or smaller than 74, c is equal to or larger than 2 and equal to or smaller than 10, d is equal to or larger than 5 and equal to or smaller than 20, (a+d) is equal to or larger than 74 and equal to or smaller than 81 and a/b is equal to or larger than 2.9 and equal to or smaller than 4.

Abstract: An information recording medium includes a first information layer and a second information layer. The first information layer includes a first recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by irradiation of a laser beam or application of current. The second information layer includes a second recording layer in which a reversible phase change is caused between a crystalline phase and an amorphous phase by the irradiation of the laser beam or the application of the current. The first recording layer is made of a first material, the second recording layer is made of a second material, and the first material is different from the second material.

Abstract: A phase-change optical information recording medium capable of recording information therein, reproducing recorded information therefrom, rewriting recorded information, and erasing recorded information therefrom, which phase-change optical information recording medium is provided with a recording layer containing therein a phase-change recording material including Ge, Ga, Sb, Te, and one element selected from the group consisting of Mg and Ca, which recording material is capable of performing a reversible phase transition from a noncrystalline phase to a crystalline phase and vice verse with the application of an electromagnetic wave thereto.

Abstract: A phase-change optical information recording medium in which information can be recorded, erased, and read includes a substrate and a recording layer overlying the substrate. The recording layer achieves a crystal phase and an amorphous phase. The absorptance Ac of the recording layer in the crystal phase against light having a wavelength of from 370 nm to 450 nm is lower than the absorptance Aa of the recording layer in the amorphous phase against the light. Information is recorded on the recording medium with a recording wavelength of from 370 nm to 450 nm at a recording pitch of 0.3 &mgr;m to 0.52 &mgr;m.

Abstract: An optical disk has a substrate, a first protective layer formed on the substrate, a recording layer formed on the first protective layer, a second protective layer formed on the recording layer, and a reflective layer formed on the second protective layer. The recording layer includes a composition expressed as (SbxTe1-x)aGebInc in which atomic ratios are 0.77≦x≦0.84, 0.85≦a≦0.95, 0.01≦b≦0.10 and 0.01≦c≦0.10 where a+b+c=1.

Abstract: Optical information-recording media comprise a first transparent substrate through which a laser beam enters, a first information-recording layer deposited on the first transparent substrate, a first reflection film formed on the first information-recording layer, an intermediate layer deposited on the first reflection film, a second information-recording layer formed on the intermediate layer, a second reflection film deposited on the second information-recording layer, and a second substrate provided on the second reflection film. The recording film of each of the first and second information-recording layers has a main composition represented by (GeTe)xSb2−yInyTe3, and its composition ratio is within ranges of 0.04≦y<2 and 4≦x≦8.

Abstract: An initialization method in which a phase change optical recording medium is initialized with a laser beam having a power density of from 15 to 22 mW/&mgr;M2 at a linear velocity of from 8 to 12 m/s. The phase change optical recording medium is formed of a transparent substrate having a guide groove on the surface thereof, a first protective layer, a recording layer, a second protective layer and a reflective layer. The recording layer material may be represented by the following composition formula: Ag&agr;X&bgr;Sb&dgr;Te&egr;Ge&ggr;, wherein X is at least one of Ga, In, Tl, Pb, Sn, Bi, Cd, Hg, Mn, Dy, Cu and Au, and &agr;, &bgr;, &dgr;, &egr;, and &ggr; have units of atomic % and satisfy particular relationships.

Abstract: A description is given of a phase-change optical data storage medium (20 having a recording stack (2) with a recording layer (6) and a metal reflective layer (3) comprising at least one transparent layer (4, 8) of the material indium tin oxide (ITO). Use of an ITO layer (4, 8) in the recording stack (2) improves the cooling behavior of the recording layer (6) combined with good optical contrast. Thus, higher possible data rates are achieved.

Abstract: An optical recording medium comprising a recording layer which comprises a phase-change recording material causing a reversible phase change between a crystalline phase and an amorphous phase by irradiation with an electromagnetic wave, wherein the phase-change recording material mainly comprises materials expressed by the composition formula X&agr;Ge&bgr;Mn&ggr;Sb&dgr;Te&egr; with each of the components respectively fulfills 0≦&agr;≦5, 1≦&bgr;≦5, 1≦&ggr;≦10, 65 ≦&dgr;<80, 15≦&egr;≦25, and &agr;≦&ggr; (where X expresses at least one of Ga and Sn, &agr;, &bgr;, &ggr;, &dgr;, and &egr; expresses atomic percentage, and fulfills &agr;+&bgr;+&ggr;+&dgr;+&egr;=100).

Abstract: An optical recording medium includes a recording layer in which a record mark can be formed by projecting a laser beam thereonto, a first dielectric layer disposed on the side of a light incidence plane with respect to the recording layer, a second dielectric layer disposed on the opposite side to the light incidence plane with respect to the recording layer, a heat radiation layer disposed on the side of the light incidence plane with respect to the first dielectric layer and a reflective layer disposed on the opposite side to the light incidence plane with respect to the second dielectric layer, the recording layer containing a phase change material represented by a general formula: (SbxTe+x)+y My wherein M is an element other than Sb and Te, the first dielectric layer containing a mixture of ZnS and SiO2, the reflective layer containing Ag or alloy containing 90 atomic % or more of Ag, and the heat radiation layer containing 90 atomic % or more of aluminum nitride.

Abstract: An optical information recording medium is composed of at least a phase-change type recording layer 4 provided on a substrate 1. The optical information recording medium is conducted to record and erase information by changing a phase of the phase-change type recording layer by irradiating light. The phase-change type recording layer is further composed of TiwGexSbyTez, wherein each of w, x, y and z is in atomic percent and satisfies following relations: 0.5≦w≦4.0, 3.4≦x≦14.5, 2.1≦y/z≦4.0 and w+x+y+z=100.