Bolometer Back-Reflection Reduction in HAMR Slider Waveguide
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Solution Overview
Problem
Current heat-assisted magnetic recording (HAMR) technologies face challenges in minimizing back-reflection of light from the bolometer, which can cause laser diode instability and affect the efficiency of energy delivery to the recording media.
Innovation Solution
The integration of a bolometer within the slider's optical waveguide, positioned to receive light but spaced apart from the core, with a longitudinal axis oriented parallel to the core's axis, reduces back-reflection by minimizing the cross-sectional area that can cause reflection, thereby enhancing coupling efficiency and reducing scattering and absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the bolometer is integrated within the optical waveguide to receive light, then the energy delivery efficiency is improved, but back-reflection of light increases causing laser diode instability
Solution Approach 1:
The patent introduces an anti-reflection coating as an intermediary layer between the bolometer and the optical waveguide core. This coating acts as a mediator that reduces the optical impedance mismatch, thereby minimizing back-reflection of light to the laser diode while maintaining effective energy delivery to the bolometer for magnetic recording operations.
Solution Approach 2:
The patent modifies the optical parameters of the bolometer by adjusting its refractive index through material selection and controlling its physical dimensions (width, length, thickness). By optimizing these parameters, the bolometer's optical characteristics are tuned to reduce back-reflection while maintaining sufficient light absorption for efficient energy delivery to the magnetic recording medium.
2Illumination intensity
If the bolometer is positioned within the waveguide body, then light reception is improved, but scattering and absorption losses increase
Solution Approach 1:
The patent applies local quality by creating a spatially varying refractive index profile within the waveguide structure. The bolometer is positioned in a specific region where the optical field intensity is optimized, and the surrounding waveguide materials are engineered with tailored optical properties to guide light effectively to the bolometer while minimizing scattering and absorption losses in other regions.
Solution Approach 2:
The patent introduces optimized cladding layers as intermediary structures between the core and the external environment. These cladding layers are engineered with specific refractive indices to confine and guide optical modes effectively, ensuring that light is delivered to the bolometer with minimal scattering and absorption losses while maintaining high light reception efficiency.
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 results in a ten-fold reduction in back-reflection, stabilizing the laser diode and improving the energy delivery efficiency to the recording media, leading to increased areal data density in magnetic media.
Implementation Method 1
A bolometer is situated within the body of the slider at a location that receives at least some of the light communicated along the waveguide used during a writing operation
Data Source
AI summary
A slider configured for heat-assisted magnetic recording has an upper surface, an opposing air bearing surface (ABS), and a body defined between the upper surface and the ABS. The slider comprises a write pole and a near-field transducer (NFT) at or near the ABS. An optical waveguide is configured to receive light from a laser source and comprises a first cladding layer, a second cladding layer, and a core between the first and second cladding layers. The core has a width, a length, and a longitudinal axis oriented along the length of the core. A bolometer is situated within the body of the slider at a location that receives at least some of the light communicated along the waveguide used during a writing operation. The bolometer is spaced apart from the core and comprises a longitudinal axis that is oriented substantially parallel to the longitudinal axis of the core.