Light Delivery Waveguide for Heat-Assisted Magnetic Recording
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Solution Overview
Problem
Current methods for delivering light to magnetic recording media in heat-assisted magnetic recording face challenges in confining light to small spots with high efficiency and low cost, particularly in aligning the light source with the slider in magnetic recording heads.
Innovation Solution
A waveguide system with a first core layer and a tapered second core layer is used to transform the light from a first mode profile to a more confined second mode profile, coupled with a near-field transducer, to efficiently focus light onto the magnetic media, utilizing cladding layers and mirrors for precise alignment and focusing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a near-field transducer with plasmonic optical antenna or aperture is used to achieve tiny confined hot spots, then light confinement is improved, but alignment precision and light delivery efficiency deteriorate
Solution Approach 1:
The waveguide is segmented into multiple core layers (first core layer and second core layer) with different functions. The first core layer receives light from the laser source, while the second core layer delivers confined light to the optical spot. This segmentation allows independent optimization of each layer's dimensions and properties, achieving both good alignment tolerance and small spot size.
Solution Approach 2:
The invention transitions from a single-plane waveguide structure to a multi-layer three-dimensional structure. By adding the vertical dimension with multiple core layers separated by cladding layers, the system achieves better light confinement and alignment tolerance simultaneously. The tapered portion of the second core layer further utilizes dimensional transformation to confine light in the lateral direction while maintaining vertical coupling.
2Ease of operation
If traditional single-layer waveguide is used, then device complexity is reduced, but light confinement and alignment tolerance deteriorate
Solution Approach 1:
The waveguide structure employs a nested configuration where the first core layer and second core layer are vertically stacked with cladding layers in between. The tapered portion of the second core layer is nested within the overall waveguide structure, creating a compact multi-layer assembly. This nesting approach achieves superior light confinement and alignment tolerance while maintaining a compact form factor suitable for integration.
3Productivity
If light is delivered with high power to achieve high areal density recording, then recording capability is improved, but light delivery efficiency and heat confinement worsen
Solution Approach 1:
The waveguide structure implements local quality optimization by having different core layers with specific dimensional characteristics suited to their functions. The first core layer has dimensions optimized for receiving light from the laser source, while the second core layer has a tapered portion with dimensions optimized for lateral light confinement. This local optimization ensures efficient power transfer from the source to the confined optical spot with minimal losses.
Solution Approach 2:
The invention utilizes parameter changes along the light propagation path. The waveguide transitions from the first core layer configuration to the second core layer with tapered portion, changing the effective modal area and confinement parameters. This gradual parameter transformation enables efficient coupling and maintains high light delivery efficiency while achieving the required power concentration for high areal density 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 approach enables high-efficiency light delivery with good alignment tolerance, achieving a diffraction-limited optical spot close to the write pole, thereby enhancing areal density recording capabilities in heat-assisted magnetic recording.
Implementation Method 1
a first core layer configured to receive light from a light source and transmit the light at a first mode profile associated with the light source
Implementation Method 2
a tapered portion of a second core layer configured to receive the light from the first core layer and transform the light to a second more confined mode profile
Implementation Method 3
Light propagating in the waveguide is focused by a focusing element, such as a planar solid immersion mirror into the near-field transducer
Data Source
AI summary
A light source and a waveguide are mounted on a recording head slider. Light rays are emitted from the light source into the waveguide. The waveguide may include two core layers for light ray transmission. The first core layer enhances light coupling efficiency from the light source to the second core layer. The second core layer transforms a profile of the light. The waveguide may include a tapered portion with a narrow opening near the light source and a wider opening near the tapered portion exit. The light rays passing through the waveguide may be directed toward a collimating mirror. The collimating mirror makes the light rays parallel or nearly parallel and re-directs the light rays to a focusing mirror. The focusing mirror focuses the collimated light rays to a spot on a magnetic media disc.