Convex Overcoat Waveguide for Laser Diode Alignment
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Solution Overview
Problem
The existing heat-assisted magnetic recording heads face challenges in aligning edge-emitting laser diodes with high precision due to variations in the position of the emission part, leading to gaps between the laser diode, waveguide, and overcoat layer, which results in reduced laser light intensity and quality variations due to foreign substances and difficulty in resin sealing.
Innovation Solution
The heat-assisted magnetic recording head design includes an edge-emitting laser diode fixed to the slider with a convex-shaped overcoat layer end face that minimizes the gap distance and allows for easy alignment, and a sealing part made of cured resin to seal the gap, ensuring efficient light transmission and reduced foreign substance interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an edge-emitting laser diode is fixed to the slider to provide high optical output, then the laser light intensity is improved, but the alignment precision between the emission part and the waveguide incident end face deteriorates due to position variations
Solution Approach 1:
The waveguide incident end face is formed with a convex shape protruding toward the laser diode emission part before the laser diode is installed. This preliminary formation of the convex shape allows for easier alignment and reduces the impact of position variations during assembly, thereby maintaining both high laser light intensity and acceptable alignment precision
Solution Approach 2:
The convex shape is formed only at the incident end face of the waveguide where alignment is critical, rather than modifying the entire waveguide structure. This localized modification concentrates the alignment facilitation effect exactly where needed - at the interface between the laser diode and waveguide - without affecting other parts of the system
2Ease of manufacture
If a gap is formed between the laser diode emitting end face and the waveguide incident end face, then the alignment process is simplified, but foreign substances can enter the gap causing quality variations
Solution Approach 1:
The convex shape of the waveguide incident end face is designed to intentionally leave a gap between the laser diode emitting end face and the waveguide, while converting the potential harm of foreign substance entry into a benefit by making the gap shape controlled and predictable. The convex geometry ensures that even with a gap, the alignment is facilitated and the gap dimensions are constrained
3Loss of energy
If the emitting end face of the laser diode is positioned close to the waveguide incident end face, then light transmission efficiency is improved, but alignment precision becomes more difficult to achieve due to position variations
Solution Approach 1:
The convex shape of the waveguide incident end face is formed in advance during waveguide fabrication, creating a built-in alignment feature that compensates for laser diode position variations. This preliminary structural preparation allows the laser diode to be positioned closer to the waveguide for improved light transmission while the convex geometry provides tolerance for alignment variations
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 design enhances the alignment precision and reduces foreign substance interference, resulting in higher laser light intensity and consistent quality across products by minimizing the gap between the laser diode and waveguide components, thereby improving near-field light generation efficiency.
Implementation Method 1
a waveguide 47 having an incident end face 47a opposed to the emission part 633a of the laser diode 60
Implementation Method 2
A surface plasmon is excited based on the light propagating through the waveguide, and the surface plasmon propagates to the near-field light generating part
Implementation Method 3
a sealing part made of cured resin to seal the gap
Data Source
AI summary
A heat-assisted magnetic recording head includes a slider, and an edge-emitting laser diode fixed to the slider. The slider has a waveguide and an overcoat layer that covers the waveguide. The laser diode has an emitting end face including an emission part for emitting laser light, and a bottom surface. The laser diode is arranged so that the bottom surface faces the top surface of the slider. The waveguide has an incident end face opposed to the emission part of the laser diode. The overcoat layer has an end face that faces the emitting end face of the laser diode. As viewed from above, the end face of the overcoat layer has a convex shape protruding toward the emitting end face of the laser diode so that a part of the end face of the overcoat layer lying over the incident end face of the waveguide comes closest to the emitting end face of the laser diode.