HAMR Head Anti-Reflective Coating for Laser Reflection Control
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Solution Overview
Problem
In heat-assisted magnetic recording (HAMR) systems, the reflection of laser light interferes with the light source, causing deterioration of laser light characteristics, which is difficult to mitigate with existing solutions due to size constraints and integration complexities in write heads.
Innovation Solution
The implementation of an anti-reflective coating on the flex side of the air bearing surface of the slider, combined with a shading layer that functions as a contact electrode and reduces stray light, minimizes light reflection back towards the light source, thereby maintaining consistent laser light characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If an isolator is used to reduce reflected light, then light reflection is reduced, but the device size increases and integration into write head becomes difficult
Solution Approach 1:
The patent introduces an anti-reflective coating layer as an intermediary substance between the laser light source and the waveguide surface. This coating layer mediates the interaction by reducing light reflection through its optical properties, eliminating the need for a separate isolator component while maintaining compact write head dimensions.
Solution Approach 2:
The patent changes the optical parameters of the waveguide surface by applying an anti-reflective coating with specific refractive index and thickness properties. This parameter change reduces the reflectivity of the surface, thereby reducing light reflection back to the laser source without requiring additional components.
2Object-affected harmful factors
If a bent or slanted waveguide with large diameter is used, then light reflection is reduced, but the waveguide structure becomes complicated and production yield decreases
Solution Approach 1:
Instead of trying to eliminate the flat waveguide surface geometry, the patent converts the potential harm of light reflection from this simple geometry into a beneficial solution by applying an anti-reflective coating. The coating transforms the reflective property into an anti-reflective property, maintaining manufacturing simplicity while achieving the desired optical performance.
3Device complexity
If reflected light is allowed to return to the light source, then the structure remains simple, but laser light characteristics deteriorate
Solution Approach 1:
The patent applies preliminary anti-action by pre-coating the waveguide surface with an anti-reflective coating before laser operation. This preventive measure stops light reflection from occurring in the first place, thereby protecting the laser light characteristics from deterioration while maintaining structural simplicity.
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 reduces light reflection to less than 0.1 percent, ensuring stable and uniform light emission, which enhances the reliability and efficiency of the HAMR process by minimizing power fluctuations and improving processing uniformity.
Implementation Method 1
an anti-reflective coating on a side opposite (e.g., a flex side) of the air bearing surface (ABS). The anti-reflective coating may include one or more anti-reflective layers. The anti-reflective coating reduces the amount of light reflected back towards a light source unit.
Implementation Method 2
A shading layer may be disposed on the anti-reflective coating and may function as a contact electrode as well as reducing stray light escaping from the laser, thus reducing the amount of stray light reaching the ABS.
Data Source
AI summary
A HAMR head includes an anti-reflecting (AR) coating on a side opposite (e.g., a flex side) of the air bearing surface (ABS). The anti-reflective coating may include one or more anti-reflective layers. The anti-reflective coating reduces the amount of light reflected back towards a light source unit. A shading layer may be disposed on the anti-reflective coating and may function as a contact electrode as well as reducing stray light escaping from the laser, thus reducing the amount of stray light reaching the ABS.