Optical Recording Medium Interlayer Crosstalk Reduction
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Solution Overview
Problem
Multilayer optical recording media face challenges in achieving stable and high-quality recording characteristics due to interlayer crosstalk caused by differences in optical characteristics and material properties between layers, leading to increased production costs and reduced recording capacity.
Innovation Solution
The optical recording medium is designed with optimized material and thickness adjustments for the reflecting film in the first recording layer to minimize interlayer crosstalk, using a dual-layer structure with a semi-transmissive reflecting layer and an intermediate layer, and employing organic dyes with shifted absorption wavelengths to enhance recording and reproduction quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple recording layers are multiplied to achieve higher recording density, then recording capacity is improved, but interlayer crosstalk and optical interference increase causing deterioration in signal quality
Solution Approach 1:
A wavelength conversion layer containing fluorescent particles is introduced between the first and second recording layers. This intermediary layer converts the recording wavelength light to a different wavelength, preventing direct optical interference between layers while allowing controlled signal transmission, thereby reducing interlayer crosstalk and improving signal quality in multilayer structures
Solution Approach 2:
The patent changes the optical parameters of the recording layers by using different dye materials with distinct absorption characteristics and introducing a wavelength conversion layer that transforms light wavelength. This parameter change allows the first and second recording layers to operate at different effective wavelengths, eliminating mutual optical interference and enabling high-density multilayer recording with maintained signal quality
2Reliability
If the optical transmittance and absorptance of recording layers are strictly controlled to achieve stable recording characteristics, then signal stability is improved, but manufacturing complexity and production costs increase
Solution Approach 1:
The patent employs dye materials with specifically engineered absorption spectra and introduces a wavelength conversion layer that transforms recording wavelength to a different wavelength. This parameter change approach allows each recording layer to have optimized optical characteristics without requiring strict control of transmittance and absorptance, simplifying manufacturing while maintaining signal stability
Solution Approach 2:
The wavelength conversion layer acts as a mediator that absorbs recording wavelength light and re-emits at a different wavelength. This intermediary mechanism naturally controls the optical interaction between layers, eliminating the need for precise control of layer transmittance and absorptance parameters, thereby reducing manufacturing complexity
3Quantity of substance
If blue laser of about 400 nm is applied to increase recording density by reducing wavelength, then recording density is improved, but the technique faces limits in recording capacity
Solution Approach 1:
Instead of continuing to reduce wavelength in the same dimension, the patent introduces a wavelength conversion layer that transforms the 400 nm blue laser light to a different wavelength range. This dimensional change in the optical spectrum allows the system to overcome the physical limits of blue laser recording while maintaining high recording density
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces interlayer crosstalk, enabling stable and high-quality recording characteristics while maintaining production efficiency and capacity, allowing for the successful recording and reproduction of data across multiple layers without significant signal distortion.
Implementation Method 1
a wavelength conversion layer having fluorescent particles; the fluorescent particles have a function of converting a recording wavelength to a wavelength other than the recording wavelength
Implementation Method 2
part of a recording wavelength is optically absorbed in an organic dye thin film used in a recording layer, and the decomposition of the organic dye thin film and the physical deformation of a recording film are caused by heat generation in the recording layer due to the optical absorption
Data Source
AI summary
According to one embodiment, an optical recording medium is provided in which interlayer crosstalk is low and in which stable and high-quality recording characteristics can be obtained. To this end, an optical recording medium comprises a first recording part which includes a first recording layer and a first light reflecting layer and which is disposed on a side closer to a light receiving surface, and a second recording part which includes a second recording layer and a second light reflecting layer and which is disposed on a side farther from the light receiving surface, the first recording part and the second recording part being stacked, wherein the thickness of the first light reflecting layer is smaller than the thickness of the second light reflecting layer.