Thermally Assisted Magnetic Head with Integrated Laser Waveguide
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Solution Overview
Problem
The existing thermally assisted magnetic heads face challenges in achieving high recording density due to the degradation of thermostability of magnetization in fine magnetic particles, and the integration of light sources and magnetic recording elements on sliders leads to complex structures and reduced yield, requiring precise positioning of waveguides and semiconductor laser diodes, which complicates assembly and reduces productive efficiency.
Innovation Solution
A thermally assisted magnetic head design featuring a semiconductor laser device that oscillates in a TM mode, with a waveguide on the slider's side surface guiding light from the laser diode to the recording medium, reducing the need for precise alignment and enhancing connection efficiency, using a p-type and n-type cladding layer configuration with arsenic-based compound semiconductor layers to prevent catastrophic optical damage and maintain high output capability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light source is located far from the slider, then the structure is simpler, but the light propagation efficiency is reduced and the apparatus structure becomes complicated
Solution Approach 1:
The patent embeds the semiconductor laser device directly within the slider structure, nesting the light source inside the component that guides it. This eliminates the need for external optical fibers and lenses, reducing both structural complexity and energy loss while integrating the light generation and guidance functions into a single compact unit.
Solution Approach 2:
The patent combines the light source (semiconductor laser device) and the light guidance structure (waveguide) into a single integrated slider assembly. This merging of functions eliminates the need for separate external components and reduces the number of interfaces, thereby simplifying the overall structure and improving light propagation efficiency.
2Volume of moving object
If the light source is integrated on the slider, then the structure is more compact, but the assembly becomes complex and positioning precision is required
Solution Approach 1:
The semiconductor laser device and waveguide are merged into a single monolithic slider structure, eliminating the need for separate assembly steps and positioning operations. This integration reduces assembly complexity while maintaining compact dimensions.
Solution Approach 2:
The slider structure is designed to perform multiple functions simultaneously: it serves as the mechanical support, the light guidance pathway, and the mounting platform for the semiconductor laser device. This multi-functionality reduces the number of separate components and simplifies the overall assembly process.
3Reliability
If precise positioning of waveguide and laser diode is required, then connection efficiency is maximized, but assembly time increases and productivity decreases
Solution Approach 1:
The waveguide and semiconductor laser device are merged into a single integrated structure where the light-emitting end surface of the laser device is inherently aligned with the light-incidence end surface of the waveguide. This eliminates the need for precise positioning and alignment operations, maintaining high connection efficiency while dramatically improving productivity.
Solution Approach 2:
The alignment between the laser device and waveguide is pre-established during the manufacturing process rather than during assembly. This preliminary action ensures optimal connection efficiency is achieved automatically without requiring time-consuming adjustment operations during final assembly.
4Quantity of substance
If fine magnetic particles are used to increase recording density, then recording density improves, but thermostability of magnetization degrades
Solution Approach 1:
The patent applies local heating to temporarily change the temperature parameter of the recording medium, which reduces the coercive force and allows writing to fine magnetic particles with large magnetic anisotropy energy. This parameter change enables high recording density while maintaining thermostability by creating a temporary window for writing that doesn't require permanent reduction of particle size.
Solution Approach 2:
The patent applies heating as a preliminary action before writing to counteract the high coercive force of fine magnetic particles. This preliminary anti-action reduces the energy barrier for magnetization reversal, enabling successful writing to high-density media without compromising the thermostability of the magnetic particles.
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 improves the productive efficiency of the thermally assisted magnetic head by reducing the need for precise positioning of the waveguide and semiconductor laser device, while maintaining high output capability and preventing catastrophic optical damage, thus enabling efficient thermally assisted magnetic recording.
Implementation Method 1
a light source, such as a semiconductor laser, is located at a position apart from a slider with a magnetic recording element for generating a magnetic field and in which light from this light source is guided through an optical fiber, a lens, etc., to a medium-facing surface of the slider
Implementation Method 2
a waveguide that is disposed at the magnetic head portion, that has a light-incidence end surface facing a light-emission end surface of the semiconductor laser device, and that guides light from the semiconductor laser device to a surface of the recording medium
Implementation Method 3
a magnetic recording element, such as an electromagnetic coil element, are stacked. The magnetic detecting element and the magnetic recording element are used to read and write data signals from and onto a magnetic disk
Data Source
AI summary
A thermally assisted magnetic head includes a slider and a light source unit. The light source unit includes a semiconductor laser diode. The semiconductor laser diode includes an n-type (Alx1Ga(1-x1))0.51In0.49P cladding layer, a p-type (Alx1Ga(1-x1))0.51In0.49P cladding layer, an n-side Alx2Ga(1-x2)As guide layer placed between these cladding layers, a p-side Alx2Ga(1-x2)As guide layer placed between these cladding layers, and an active layer placed between these guide layers.