Inverse Tapered Waveguide for HAMR Laser Alignment
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Solution Overview
Problem
Conventional heat-assisted magnetic recording (HAMR) transducers face performance issues due to misalignments between the laser mode and waveguide mode during fabrication, leading to reduced energy coupling and adverse effects on yield.
Innovation Solution
An inverse tapered waveguide is introduced, optically coupled with the laser, featuring a wider bottom section near the air-bearing surface and diverging sides, which enhances tolerance to laser misalignments and improves energy coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional tapered waveguide is used, then the waveguide mode is confined to a smaller region, but the tolerance to laser misalignment is reduced
Solution Approach 1:
The patent inverts the conventional tapered waveguide geometry by using an inverse tapered waveguide where the waveguide mode area increases from the entrance to the exit, rather than decreasing. This inversion allows the waveguide to accept a broader range of laser mode positions while still confining the mode effectively at the exit region, thereby improving alignment tolerance without sacrificing mode confinement.
2Loss of energy
If the waveguide entrance is made smaller to improve mode confinement, then the coupling efficiency improves, but the alignment tolerance decreases
Solution Approach 1:
The inverse tapered waveguide creates a dynamic mode evolution where the mode area expands along the propagation direction. This dynamic behavior allows the waveguide to adapt to variations in laser positioning, maintaining effective coupling even when alignment is not perfect, thus reducing sensitivity to manufacturing precision requirements.
3Loss of energy
If the waveguide is designed with high precision alignment requirements, then the energy coupling efficiency is maximized, but the fabrication yield decreases
Solution Approach 1:
The patent changes the geometric parameters of the waveguide from a conventional tapered design to an inverse tapered design. This parameter change fundamentally alters the coupling characteristics, making the system less sensitive to alignment variations and thereby improving fabrication yield without sacrificing energy coupling 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
The inverse tapered waveguide design increases the tolerance to laser misalignments, ensuring more HAMR disk drives meet minimum energy coupling requirements and improves fabrication yield by confining the waveguide mode near the center, even with misalignments.
Implementation Method 1
The inverse tapered waveguide includes an entrance distal from the ABS, a bottom proximate to the ABS, a first side and a second side opposite to the first side. The first side and the second side diverging such that at least a portion of the inverse tapered waveguide between the bottom and the top is wider than the entrance.
Data Source
AI summary
A heat-assisted magnetic recording (HAMR) transducer is coupled with a laser for providing energy and has an air-bearing surface (ABS) configured to reside in proximity to a media during use. The HAMR transducer includes a write pole, at least one coil, and an inverse tapered waveguide optically coupled with the laser. The write pole is configured to write to a region of the media. The coil(s) energize the write pole. The inverse tapered waveguide includes an entrance distal from the ABS, a bottom proximate to the ABS, a first side and a second side opposite to the first side. The first side and the second side diverging such that at least a portion of the inverse tapered waveguide between the bottom and the top is wider than the entrance.