Multilayered Waveguide Stabilizing Light Spot Position
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Solution Overview
Problem
In thermally-assisted magnetic recording, achieving a high optical coupling efficiency and precise positioning of the light spot center in the waveguide is challenging due to the degradation of optical coupling efficiency with reduced waveguide thickness and significant deviations in light spot position caused by slight displacements of the light source.
Innovation Solution
A multilayered waveguide structure with alternating refractive indices and varying lengths of layer groups, where the first group with the highest refractive index is positioned at the end in the stacking direction to stabilize the light-emitting spot center near the main magnetic pole, ensuring high optical coupling efficiency and precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thickness of the waveguide in the stacking direction is reduced to bring the light-emitting end closer to the main magnetic pole, then the position of the light spot center can be closer to the main magnetic pole, but the optical coupling efficiency between the light source and the waveguide is degraded
Solution Approach 1:
The patent transitions from controlling light spot position through waveguide thickness adjustment (one-dimensional approach) to using a multilayered structure with varying refractive indices (adding structural dimensionality). The multilayered waveguide uses layers with different refractive indices to control light propagation and positioning without compromising optical coupling efficiency, effectively solving the contradiction by operating in a higher-dimensional design space.
Solution Approach 2:
The patent changes the refractive index parameter distribution within the waveguide structure by implementing a multilayered design. By varying the refractive indices of different layers and their thicknesses, the light spot center position can be precisely controlled while maintaining optimal optical coupling efficiency. This parameter optimization approach allows independent control of coupling efficiency and position accuracy.
2Measurement precision
If a multilayered structure is used to control the light spot center position, then the position can be adjusted, but the position of the light spot center deviates significantly from the intended position due to slight displacement of the light source
Solution Approach 1:
The patent applies local quality by creating regions with different refractive indices within the waveguide structure. Each layer is designed with specific local optical properties that collectively guide and stabilize the light spot center position. This localized control of refractive indices ensures that the light spot center remains stable even when the light source experiences slight displacements, as the multilayered structure compensates for position variations.
3Productivity
If the waveguide thickness is reduced to improve recording density, then the light spot can be positioned closer to the main magnetic pole, but the optical coupling efficiency is degraded making it difficult to introduce sufficient light intensity
Solution Approach 1:
The patent employs composite material structure by combining multiple layers with different refractive indices within the waveguide. This composite design allows the waveguide to maintain thin overall thickness for high recording density while the internal layer structure optimizes light propagation and coupling efficiency. The composite structure enables sufficient light intensity to be introduced into the waveguide despite the reduced thickness.
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 configuration maintains a stable light-emitting spot center position and enhances optical coupling efficiency, allowing for effective thermally-assisted magnetic recording with improved light use efficiency and precise alignment of the write field.
Implementation Method 1
a waveguide (35) having a multilayered structure in which refractive indexes of layers having a surface contact with each other are different from each other
Data Source
AI summary
A waveguide is provided, in which the optical coupling efficiency to a light source is sufficiently high, and the light-emitting spot center is stably provided at the intended position. The waveguide comprises a multilayered structure in which refractive indexes of layers having a surface contact with each other are different from each other. The multilayered structure is divided into a plurality of groups, and the length from the light-receiving end surface to the light-emitting end surface of one group is different from that of the neighboring group, and the protruded light-emitting end surface of the first group defined as a group that has the largest length includes a center of the light-emitting spot. In this waveguide, the state in which the light-emitting spot center is positioned within the light-emitting end surface does not easily be changed, even when the light-receiving spot center within the light-receiving end surface is rather displaced.