JPH0352141A - optical recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Fields of the Invention Optical recording media used in optical disks for information recording, etc. Conventional technology related to wavelength multiplexing optical recording media for realizing high-density recording, etc. In optical recording technology that uses optical recording media that use materials as recording bodies, multiple bits of information are recorded in one recording spot using dyes with different absorption maximum wavelengths as a method for high-density recording of information. As one such method, an optical recording medium in which dye thin films having different peak absorption wavelengths are sequentially laminated has been proposed (for example, Japanese Patent Application Laid-Open No. 61-205187). Recording onto a medium 《The laser beam with the oscillation wavelength corresponding to each peak absorption wavelength is irradiated, and the corresponding peaks are erased or reduced by the thermal mode. Multiplex recording is performed by the absorption change of each peak. Problems to be Solved by the Invention Even though organic photochromic compounds and dye materials forming J-aggregates are used as optical recording media applied to the multiplex recording system, in order to increase the wavelength multiplicity in the above recording system, When the absorption spectrum of a selected optical recording medium overlaps with that of another optical recording layer (when the absorption spectrum of a certain optical recording layer overlaps with the absorption spectrum of another optical recording layer), The problem is that the optical recording layer other than the optical recording layer absorbs the light and the absorption spectrum changes. The present invention L&
The purpose of the present invention is to solve the problems of the prior art. An optical recording layer that records in an active thermal mode even if the optical recording medium is separated by more than the half-width. At wavelengths that are more than the absorption half-width away from the maximum wavelength (upper), the absorption does not change at all due to light irradiation with the energy value necessary to perform sufficient recording at the absorption maximum wavelength. When selecting dyes in each optical recording layer, the maximum absorption wavelength of the dye is selected to be more than half-width apart from the maximum absorption wavelength of the other optical recording layer, thereby preventing crosstalk due to light absorption between the recording layers. In the following, examples of the present invention will be explained with reference to the drawings, but in this example, it is possible to improve the wavelength multiplicity. As an optical recording layer, an optical recording medium was prepared on a substrate using the Langmuir-Projet method.
Dye B, Dye C, and Dye A (hereinafter referred to as blank spaces) Dye B Dye C Figures 1 (a) and (b) show the absorption spectrum and recording wavelength characteristics of dye A. Dye A Ho J aggregate peak wavelength is approximately 700 nrrK Absorption half width is 26 nm Recording wavelength characteristics C The change in peak absorbance was measured with the energy at each wavelength of recording light being constant Change in peak absorbance (Table Shape of absorption spectrum The characteristics change the most during optical recording at the peak wavelength.

When recording at a wavelength that is more than half-width apart from the peak wavelength of dye A, the absorbance does not change at all, but the other dyes B and C have similar characteristics. Figure 2 shows the results of fabricating and evaluating a 3-wavelength multiplexing optical recording medium using this as an optical recording layer.Figure C↓
3.Dye composed of 3 optical recording layers of dye B and dye C.
Showing the recording results of the wavelength multiplexing optical recording medium, (a) shows the recording results for dye A, (b) shows the recording results for dye B, and (c) shows the recording results for dye C. The solid line in the figure is the absorption spectrum of the optical recording medium before recording, and the dotted line is the spectrum after recording on each recording layer. In addition, optical recording is performed at a wavelength corresponding to each peak.The value of green energy recorded is the value at which the peak absorbance change rate is approximately 50%.Dye A. The wavelengths of the aggregate peaks of dye B and dye C are 700 nm, 64 nm, and 600 nm, respectively, and the half-widths are 26 nm and 27 nm, respectively.
l 14 nm, and the peak wavelength interval between the optical recording layers is set to be more than the half width of each dye. △ As shown in Figure 2, recording in each optical recording layer does not cause crosstalk due to light absorption.However, optical recording media can be constructed using dyes whose absorption peak intervals are within half width If the wavelength division multiplexing optical recording method cannot be applied, crosstalk occurs due to light absorption when sufficient recording is performed in each optical recording layer. The invention makes it possible to prevent crosstalk caused by optical absorption, which occurs between optical recording layers of optical recording media used in wavelength multiplexing optical recording systems.

[Brief explanation of drawings]

Figure 1 is a graph showing the absorption spectrum of dye A and the recording wavelength characteristics of an optical recording layer made of dye A, and Figure 2 is a graph showing the absorption spectrum of dye A,
2 is a graph showing the recording results of a three-wavelength multiplexing optical recording medium configured with three optical recording layers of dye B and dye C.

Claims (1)

[Claims] In an optical recording medium that is composed of a plurality of types of optical recording layers each having a different light absorption wavelength region, and in which each layer is selectively recorded by light of a corresponding wavelength, the wavelength width between the absorption maximum wavelengths of the optical recording layers is different from each other. An optical recording medium characterized in that the optical recording layers are separated by more than the half-width of light absorption.