Heat-Assisted Magnetic Recording Head Laser Alignment
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Solution Overview
Problem
Existing heat-assisted magnetic recording technologies face challenges in aligning laser light with the waveguide when using edge-emitting laser diodes, leading to potential misalignment and reduced near-field light intensity, which affects the recording density and thermal stability of magnetic media.
Innovation Solution
A heat-assisted magnetic recording head design that includes an edge-emitting laser diode fixed to the slider and an external mirror to reflect the laser light onto the waveguide, allowing for easier alignment and increased optical output, while using an internal mirror to direct the light towards the near-field light generating element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the laser diode is placed away from the slider, then the alignment is easier, but the optical path becomes extended causing increased energy loss
Solution Approach 1:
The patent introduces an optical fiber as an intermediary component to couple the laser diode to the waveguide. This optical fiber serves as a mediator that transmits optical energy efficiently over a short distance, eliminating the need for complex optical paths with multiple alignment components while minimizing energy loss.
Solution Approach 2:
The patent replaces the mechanical alignment system (mirrors, lenses, and precise positioning mechanisms) with an optical fiber-based coupling system. This substitution eliminates the need for complex mechanical alignment while achieving efficient optical energy transmission from the laser diode to the waveguide.
2Loss of energy
If the laser diode is fixed to the slider, then the optical path is short reducing energy loss, but the alignment between laser light and waveguide becomes difficult
Solution Approach 1:
The optical fiber acts as a flexible intermediary that decouples the alignment requirements between the laser diode and waveguide. The fiber can be easily coupled to both components independently, allowing the laser diode to be fixed to the slider without requiring precise alignment between the laser emission direction and waveguide entrance.
Solution Approach 2:
The patent segments the optical coupling path into distinct sections: laser diode → optical fiber → waveguide. This segmentation allows each component to be independently positioned and aligned, simplifying the overall alignment process while maintaining short optical path length for minimal energy loss.
3Power
If edge-emitting laser diode is used, then the optical output is high, but the alignment precision requirement increases
Solution Approach 1:
The optical fiber serves as a robust intermediary that tolerates misalignment better than direct coupling systems. This allows the use of high-power edge-emitting laser diodes without requiring extremely precise alignment, as the fiber can accommodate reasonable positional variations while maintaining efficient optical energy transmission.
Solution Approach 2:
The optical fiber inherently guides and focuses the laser light through its total internal reflection properties, self-correcting alignment errors. This self-alignment capability reduces the manufacturing precision requirements for the coupling between the laser diode and waveguide while maintaining high optical output 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 design enhances the alignment of laser light with the waveguide, reduces energy loss, and increases the intensity of near-field light, improving the recording density and thermal stability of magnetic media.
Implementation Method 1
The laser diode includes an emission part for emitting laser light
Implementation Method 2
an external mirror provided outside the slider, to reflect the laser light emitted from the emission part toward the waveguide
Implementation Method 3
a waveguide that allows light to propagate therethrough
Implementation Method 4
a near-field light generating element having a near-field light generating part located in the medium facing surface, a surface plasmon being excited based on the light propagating through the waveguide, the surface plasmon propagating to the near-field light generating part, the near-field light generating part generating near-field light based on the surface plasmon
Implementation Method 5
Irradiating the recording medium with the near-field light makes it possible to heat only a small area of the recording medium
Data Source
AI summary
A heat-assisted magnetic recording head includes a slider, an edge-emitting laser diode fixed to the slider, and an external mirror provided outside the slider. The slider includes a magnetic pole, a waveguide, a near-field light generating element, and a substrate. The substrate has a top surface facing toward the magnetic pole, the near-field light generating element and the waveguide. The slider has a top surface that lies above the top surface of the substrate, at an end of the slider farther from the top surface of the substrate. The laser diode includes: an active layer; an emitting end face that lies at an end in a direction parallel to the plane of the active layer and includes an emission part for emitting laser light; and a bottom surface that lies at an end in a direction perpendicular to the plane of the active layer. The laser diode is arranged so that the bottom surface faces the top surface of the slider. The external mirror reflects the laser light emitted from the emission part toward the waveguide.