Waveguide Core Segmentation for Polarization Rotation
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Solution Overview
Problem
Existing waveguides for thermally-assisted magnetic recording face challenges in maintaining high precision of core shapes and preventing degradation in light propagation characteristics, particularly when using TE-mode lasers, which require polarization rotation or beam diameter changes, leading to inefficiencies in near-field light generation.
Innovation Solution
A waveguide design with a core comprising two layers of different shapes, surrounded by a cladding, where the etching stopper layer is formed from a material with a refractive index close to the core material, ensuring precise shape control and minimizing degradation by maintaining a refractive index difference within 10% of the core's index, allowing for effective polarization rotation and beam diameter adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If TE-mode laser is used for near-field light generation, then device size is reduced and placement is simplified, but polarization rotation or beam diameter change is required which reduces generation efficiency
Solution Approach 1:
A polarization rotation layer is introduced as an intermediary component between the TE-mode laser and the plasmon generator. This layer rotates the polarization of the laser light from TE-mode to TM-mode, enabling efficient near-field light generation without changing the laser orientation, thus resolving the contradiction between ease of placement and generation efficiency
2Manufacturing precision
If core shape precision is increased for polarization rotation function, then light propagation characteristics are improved, but manufacturing difficulty increases
Solution Approach 1:
The core is segmented into multiple layers with different refractive indices, where each layer has a specific function. The first layer handles light propagation while the second layer provides polarization rotation. This segmentation allows precise control of light propagation characteristics while simplifying the manufacturing process by assigning specific functions to specific layers
Solution Approach 2:
The invention changes the refractive index parameter by using multiple materials with different refractive indices for different layers. By carefully selecting materials with appropriate refractive index differences (within 10% as specified), the patent achieves precise polarization rotation while maintaining manufacturability through standard materials and processes
3Measurement precision
If etching stopper layer material is used with very different refractive index from core, then etching selectivity is improved, but light propagation degradation occurs
Solution Approach 1:
The refractive index parameter of the etching stopper layer is optimized to be within 10% of the core material's refractive index. This parameter change allows the etching stopper layer to maintain good etching selectivity for precise positioning while minimizing optical degradation, thus resolving the contradiction between positioning precision and light propagation reliability
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
The solution enhances the precision of waveguide core shapes and prevents degradation in light propagation, enabling efficient generation of high-intensity evanescent light and near-field light, thereby improving data writing capabilities in thermally-assisted magnetic recording.
Implementation Method 1
The core generates evanescent light at the evanescent light generating surface from laser light propagating through the core
Implementation Method 2
surface plasmons are excited on the plasmon exciting section through coupling with the evanescent light
Implementation Method 3
the electric field of the laser light propagating through the core oscillates in a direction perpendicular to the evanescent light generating surface
Data Source
AI summary
A manufacturing method for a waveguide includes forming a core including a first and a second layer. The first layer has a top surface including a first region opposed to a bottom surface of the second layer, and a second region not opposed to the bottom surface of the second layer. Forming the core includes a step of forming an initial first layer, an etching stopper layer on the second region of the top surface of the initial first layer, an initial second layer on the initial first layer and the etching stopper layer, and a step of etching the initial second layer until the etching stopper layer is exposed, to make the initial second layer into the second layer. A difference between the refractive index of the etching stopper layer and the core is smaller than or equal to 10% of the refractive index of the core.