VCSEL Array Beam Combiner for HAMR Head
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Solution Overview
Problem
Current heat-assisted magnetic recording (HAMR) technologies face challenges with edge emitting laser diodes (EELDs), including high costs, mode-hops, limited alignment tolerance, reliability issues, and increased disk-to-disk spacing due to their design and operation, which hinder the achievement of high recording densities in magnetic media drives.
Innovation Solution
A magnetic recording head incorporating a vertical cavity surface emitting laser (VCSEL) device and a waveguide structure with multimodal interference (MMI) combiner, where the waveguide channels are optimized for phase coherence, allowing for the combination of multiple laser beams into a single powerful beam to enhance recording capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If edge emitting laser diode (EELD) is used as light source, then laser power can be achieved, but cost increases, alignment tolerance decreases, and reliability deteriorates
Solution Approach 1:
The patent uses VCSELs as a copy alternative to EELD, maintaining laser functionality while eliminating the reliability issues and alignment problems of EELD. The VCSEL array provides multiple laser sources that can be combined to achieve the necessary power without the drawbacks of edge-emitting lasers
Solution Approach 2:
The patent combines multiple VCSEL laser beams using a beam combiner to achieve the total power needed for HAMR. This merging approach allows using lower-power, more reliable VCSELs instead of high-power EELD, resolving the contradiction between power requirement and reliability
2Power
If EELD is used as light source, then laser power can be achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive EELD with VCSEL array, using multiple lower-cost laser sources to achieve the required power. VCSELs are more cost-effective to manufacture and integrate into the slider assembly
Solution Approach 2:
The patent combines multiple VCSEL beams to achieve the total power needed, allowing the use of cheaper individual VCSEL components instead of expensive EELD, thus reducing overall manufacturing cost while maintaining power requirements
3Power
If EELD is used as light source, then laser output can be achieved, but alignment tolerance decreases
Solution Approach 1:
The patent uses VCSELs with their superior beam characteristics that provide inherent alignment tolerance. The vertical cavity surface emitting laser design produces beams that are more forgiving to alignment variations compared to edge-emitting lasers
Solution Approach 2:
The patent combines multiple VCSEL beams with relaxed alignment requirements, allowing for easier manufacturing and assembly. The array configuration and beam combining process tolerate alignment variations better than single EELD systems
4Power
If EELD is used as light source, then laser function can be achieved, but disk-to-disk spacing increases
Solution Approach 1:
The patent uses VCSELs with their compact design and superior optical characteristics to achieve the necessary laser function in a more space-efficient manner, reducing the required disk-to-disk spacing compared to EELD systems
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 reduces costs, improves alignment tolerance, increases reliability, and decreases disk-to-disk spacing, enabling higher recording densities and HDD capacity by efficiently delivering the necessary power to the near-field transducer (NFT) for effective magnetic recording.
Implementation Method 1
The VCSEL device is capable of emitting a plurality of lasers through the plurality of waveguide channels
Implementation Method 2
a multimodal interference (MMI) combiner coupled to the waveguide channels
Implementation Method 3
each waveguide channel is controllable, or otherwise phase coherent with adjacent waveguide channels. The plurality of lasers are phase coherent when input into the MMI combiner
Implementation Method 4
a waveguide structure coupled between the NFT and the VCSEL device. The waveguide structure comprises a plurality of waveguide channels
Implementation Method 5
a near-field transducer (NFT)... 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
The present disclosure generally relates to a magnetic recording head for a magnetic media drive. The magnetic recording head comprises a near field transducer (NFT), a vertical cavity surface emitting laser (VCSEL) device, and a waveguide structure coupled between the NFT and the VCSEL device. The waveguide structure comprises a plurality of waveguide channels and a multimodal interference (MMI) combiner coupled to the waveguide channels. One or more of a curvature, a path length, and a propagation length of each of the waveguide channels is optimized such that each waveguide channel is controllable, or otherwise phase coherent with adjacent waveguide channels. The VCSEL device is capable of emitting a plurality of lasers through the plurality of waveguide channels, and the plurality of lasers are phase coherent when input into the MMI combiner. The MMI combiner combines a power of the plurality of lasers, which is output to the NFT.