Split Assist Cores for HAMR Spot Size Converter
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Solution Overview
Problem
Current heat-assisted magnetic recording (HAMR) technologies face challenges in achieving high recording densities due to limitations in the coupling efficiency between light sources and waveguides, leading to issues with laser power usage, stability, and temperature control.
Innovation Solution
The implementation of a spot size converter (SSC) with split assist core structures and a multimodal interference (MMI) device in the HAMR-based magnetic recording head assembly, which includes multiple assist cores and waveguides to enhance the coupling efficiency of light from the laser source to the near-field transducer (NFT), optimizing the light distribution and reducing the power required for data writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the width and pitch of write tracks are narrowed to achieve higher recording densities, then the recording density is improved, but the surface area of the main pole decreases, limiting the effectiveness of the magnetic recording write head
Solution Approach 1:
The patent introduces an intermediary heating mechanism (laser source and waveguide) that acts as a mediator between the magnetic write head and the magnetic medium. This intermediary delivers thermal energy to the medium to enhance its writeability without requiring a larger main pole, thus resolving the contradiction between high recording density and sufficient pole area.
Solution Approach 2:
The patent changes the physical state of the magnetic medium by introducing thermal energy through laser heating. This parameter change (temperature increase) makes the medium more susceptible to magnetic field changes, allowing effective writing with smaller pole areas and higher recording densities.
2Quantity of substance
If a laser source is used for heat-assisted magnetic recording, then the recording density is improved, but the coupling efficiency between the light source and the waveguide structure becomes challenging
Solution Approach 1:
The patent segments the waveguide structure into multiple sections with different refractive indices and geometries. This segmentation allows progressive mode transformation and better coupling of laser light into the waveguide, reducing energy loss and improving coupling efficiency.
Solution Approach 2:
The patent employs graded-index waveguides where the refractive index varies continuously along the waveguide length. This parameter change enables adiabatic mode coupling, significantly improving the efficiency of light transfer from the laser source to the heating region.
3Quantity of substance
If the main pole becomes smaller to narrow write tracks, then the recording density is improved, but the recording field becomes smaller, limiting the effectiveness of the magnetic recording write head
Solution Approach 1:
The patent uses thermal energy as an intermediary to enhance the magnetic recording process. The laser-heated region temporarily increases the susceptibility of the magnetic medium, effectively amplifying the impact of the smaller magnetic field generated by the reduced main pole, thus maintaining recording effectiveness at higher densities.
Solution Approach 2:
The patent exploits thermal-induced phase changes in the magnetic medium's magnetic susceptibility. Heating the medium changes its magnetic properties, making it more responsive to the write field, thereby compensating for the reduced pole size and maintaining effective recording.
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 improves the coupling efficiency between the light source and the waveguide, stabilizing the light source operation, increasing its lifetime, and reducing stray light, thereby enhancing the overall performance and stability of the magnetic recording head.
Implementation Method 1
a laser source is located next to or near the write element of the magnetic recording write head in order to produce heat
Implementation Method 2
a first waveguide coupled to the NFT; a multimodal interference (MMI) device having a first end and a second end, wherein the first end is coupled to the first waveguide
Implementation Method 3
a near field transducer (NFT) disposed adjacent to the main pole
Implementation Method 4
produce heat, such as a laser source exciting a near-field transducer (NFT) to produce heat at a write location of a magnetic recording medium
Data Source
AI summary
Spot size converter (SSC) in a HAMR magnetic recording head assembly have a plurality of split assist core structures. Each split assist core structure includes multiple assist cores and a main waveguide. Each split core may also include one or more side waveguides such that the main waveguide is sandwiched between the side waveguides and top and bottom assist cores. Adjacent split assist core structures, may share assist cores. The split assist core structures reduce light source power utilized to write data to magnetic media.