Optical Storage Track Pitch Reduction via Super-RENS and Polarization
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Solution Overview
Problem
Current optical storage media, such as Blu-Ray discs, face limitations in data density due to the diffraction limit of laser beams, which restricts the track pitch and data storage capacity.
Innovation Solution
The implementation of a super resolution near-field structure (Super-RENS) with a mask layer and a polarized laser beam that utilizes both TE and TM polarization components to reduce the track pitch, allowing for increased data density by alternating partitioned and not partitioned marks in a track structure, enabling a track pitch reduction to 200 nm with a 405 nm laser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional laser beam is used for reading optical storage media, then the diffraction limit restricts the track pitch to 320 nm or more, but using a super resolution near-field structure with a mask layer and polarized laser beam allows track pitch reduction to 200 nm, increasing data density by a factor of 1.6
Solution Approach 1:
The optical pickup is divided into two independent detection channels: one for data reading and another for tracking control. Each channel uses a specific polarization component (TM for data, TE for tracking), allowing independent optimization of each function and enabling track pitch reduction without compromising tracking performance
Solution Approach 2:
The invention changes the polarization parameter of the laser beam to utilize both TE and TM components simultaneously. By adjusting the polarization state, the system achieves super-resolution capability for data reading while maintaining adequate tracking signal strength, enabling track pitch reduction to 200 nm
2Quantity of substance
If a mask layer is added to achieve super resolution near-field effect, then data density increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The mask layer is designed to serve multiple functions: it provides the super-resolution near-field effect for data reading, maintains structural integrity of the optical disc, and enables polarization-based differentiation between data and tracking signals. This multi-functionality reduces the need for additional separate components
Solution Approach 2:
The optical disc uses a composite structure combining the mask layer with the data layer and reflective layer. The mask layer material is specifically selected to provide the required optical properties for super-resolution while being compatible with existing optical disc manufacturing processes
3Measurement precision
If partitioned marks are used in alternating tracks, then track pitch can be reduced to 200 nm, but the complexity of the track structure increases
Solution Approach 1:
The track structure is segmented into two types: tracks with partitioned marks and tracks with not partitioned marks. This segmentation allows the system to maintain simple track geometry in some tracks while achieving high density in alternating tracks, reducing overall manufacturing complexity
Solution Approach 2:
Different tracks have different mark partitioning characteristics tailored to their specific function. Tracks requiring high density have partitioned marks, while tracks requiring simpler structure have not partitioned marks. This local differentiation optimizes both density and manufacturability
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 increases data density by a factor of 1.6 in the tracking direction compared to Blu-Ray discs, while maintaining a push-pull signal for tracking control, and allows for a track pitch of 400 nm to be resolved easily with a Blu-Ray pickup unit, enhancing data storage capacity without requiring a mask layer for the Super-RENS effect.
Implementation Method 1
a super resolution near field structure for storing of data with a high data density
Implementation Method 2
a polarized laser beam that utilizes both TE and TM polarization components
Implementation Method 3
a pickup comprising a laser for illuminating the optical storage medium and a photo-detector for detecting the reflected light of the laser beam
Data Source
Figure 1A~3
Figure 2
Figure 4A~5B
AI summary
The optical storage medium comprises tracks (T1-T3) with a mark/space data structure, wherein the tracks comprise alternately partitioned marks (3) and not partitioned marks (2). The partitioned marks are partitioned in particular in tracking direction and are partitioned in two parts, advantageously in two equal parts. The partitions are arranged advantageously such that one track comprises not partitioned marks and a neighboring track comprises partitioned marks, for reducing the track pitch of the optical storage medium and for providing an increased data capacity. The optical storage medium is in a preferred embodiment an optical disc comprising a mask layer with a suitable material for providing a super resolution near field effect, and the data structure of the optical disc comprises two spirals which have either partitioned marks or not partitioned marks. This allows to increase the data density in tracking direction by a factor of two with regard to a Blu-Ray disc. An apparatus for reading the data of a respective optical storage medium comprises a pick-up unit with a laser and a first optical element for providing a TM polarized beam and a TE polarized beam, a second optical element for separating the reflected TM and TE polarized beams, and a first and a second detector. The TM polarized beam is guided to the first detector for providing a data signal and the TE polarized beam is guided to the second detector for providing a tracking signal.