Edge-Emitting Laser Diode Placement in HAMR Head
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Solution Overview
Problem
In heat-assisted magnetic recording, edge-emitting laser diodes generate heat that degrades the magnetoresistive element and causes signal degradation due to heat transfer and stray capacitance issues when integrated with existing magnetic recording heads.
Innovation Solution
The heat-assisted magnetic recording head design includes an edge-emitting laser diode fixed to the slider with its bottom surface facing the substrate, ensuring effective heat transfer to the substrate while avoiding overlap with reproduction wiring layers to prevent heat from reaching the magnetoresistive element, and incorporating a conductive layer to prevent stray capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an edge-emitting laser diode is integrated with the magnetic recording head to enable heat-assisted magnetic recording, then heat can be applied to the magnetic recording medium to lower coercivity for data recording, but the laser diode generates heat that degrades the magnetoresistive element and causes signal degradation
Solution Approach 1:
The head structure is divided into distinct functional regions: the laser diode is positioned in a dedicated area with its bottom surface facing the substrate, separated from the magnetoresistive element by spatial arrangement. The overlapping portion of the laser diode with the substrate is specifically designed to direct heat transfer away from sensitive components, segmenting the thermal pathways to protect the magnetoresistive element while enabling heat-assisted recording.
Solution Approach 2:
The substrate serves as an intermediary thermal management layer between the laser diode and the magnetoresistive element. The laser diode's bottom surface faces the substrate to transfer heat effectively, while the substrate's thermal properties and structure mediate the heat distribution, preventing direct heat transfer to the magnetoresistive element and reducing thermal degradation.
2Use of energy by moving object
If the laser diode is positioned to overlap with the substrate for effective heat transfer, then heat can be efficiently applied to the magnetic recording medium, but stray capacitance issues arise that cause signal degradation
Solution Approach 1:
The laser diode is positioned to overlap specifically with certain portions of the substrate rather than uniformly across the entire substrate area. This localized overlapping arrangement optimizes heat transfer to the magnetic recording medium while minimizing the laser diode's overlap with reproduction wiring layers and other signal-carrying structures, thereby reducing stray capacitance and preserving signal quality.
3Device complexity
If the laser diode is placed close to the magnetoresistive element for compact head design, then device complexity is reduced, but heat from the laser diode directly degrades the magnetoresistive element
Solution Approach 1:
Instead of arranging components only in the horizontal plane, the laser diode is positioned in the vertical dimension with its bottom surface facing the substrate. This three-dimensional arrangement allows the laser diode to be integrated into the head structure without increasing horizontal footprint, while the vertical separation and substrate positioning prevent direct heat exposure to the magnetoresistive element, achieving compactness without thermal degradation.
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 effectively transfers heat to the substrate, reducing the adverse effects on the magnetoresistive element and improving signal quality by preventing heat-induced degradation and stray capacitance, thereby enhancing the recording head's performance.
Implementation Method 1
a light source that emits laser light... an edge-emitting laser diode fixed to the slider
Implementation Method 2
a near-field light generating element... generates near-field light based on the surface plasmon
Implementation Method 3
A surface plasmon is excited based on the light that propagates through the waveguide
Implementation Method 4
the laser diode is arranged so that the bottom surface... faces the top surface of the slider... effectively transfers heat to the substrate
Implementation Method 5
a magnetoresistive element... detects a magnetic signal sent from the magnetic recording medium
Implementation Method 6
The coil produces a magnetic field corresponding to data to be recorded... The magnetic pole... produces a recording magnetic field
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 includes: a substrate; and an MR element, two reproduction wiring layers, a coil, two recording wiring layers, a magnetic pole, a near-field light generating element, and a waveguide that are stacked above the top surface of the substrate. The two reproduction wiring layers supply a sense current to the MR element. The two recording wiring layers supply a coil current to the coil, 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. As viewed from above, the laser diode does not overlap the two reproduction wiring layers but overlaps at least one of the two recording wiring layers.