Multi-Mode Interference Device for HAMR Waveguide Fabrication
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Solution Overview
Problem
Conventional heat-assisted magnetic recording (HAMR) technologies face challenges in scaling down optical components, leading to fabrication difficulties and unreliable operation due to the need for precise energy delivery and monitoring, particularly as HAMR transducers are miniaturized.
Innovation Solution
The implementation of a multi-mode interference (MMI) device within the waveguide structure, which simplifies fabrication, enhances tolerance to wavelength uncertainties, and reduces space occupancy, by efficiently splitting and recombining light for improved power monitoring and alignment, thereby facilitating better performance and yield in HAMR disk drives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional HAMR waveguide structures are used, then optical energy can be delivered to heat the media, but fabrication becomes difficult and reliability decreases as components are scaled to smaller sizes
Solution Approach 1:
The waveguide is segmented into multiple arms (first arm, second arm, third arm) with distinct functions. The MMI device divides the waveguide into separate propagation paths that can be independently optimized, making fabrication more manageable and reliable at scaled dimensions.
Solution Approach 2:
The waveguide structure performs multiple functions: energy delivery to heat the media, power monitoring through tapping, and alignment monitoring. The MMI device enables these multiple functions within a single integrated structure, improving reliability without requiring separate components that would complicate fabrication.
2Measurement precision
If conventional waveguide tapping is used for power monitoring, then energy can be monitored, but the structure becomes complex and fabrication becomes more difficult
Solution Approach 1:
The power monitoring function is merged into the main waveguide structure through the MMI device. The tapping waveguide is integrated with the multi-arm waveguide rather than being a separate component, reducing overall device complexity while maintaining monitoring precision.
Solution Approach 2:
The MMI device acts as an intermediary that couples a small amount of energy from the main waveguide to the tapping waveguide. This intermediary structure enables precise power monitoring without significantly disrupting the main energy delivery path, simplifying the overall design.
3Area of stationary object
If conventional waveguide structures are used, then light can be delivered to the NFT, but space occupancy is larger and fabrication tolerance to wavelength variations is reduced
Solution Approach 1:
The MMI device utilizes dynamic interference patterns of light waves propagating through multiple arms. The constructive and destructive interference creates wavelength-tolerant operation, allowing the device to function across a range of wavelengths while occupying minimal space.
Solution Approach 2:
The multi-arm waveguide structure extends the optical path in multiple spatial dimensions rather than a single linear path. This dimensional expansion allows for compact footprint while providing inherent wavelength tolerance through the interference of multiple propagation paths.
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
The MMI device improves the fabrication and performance of HAMR disk drives by allowing for more precise energy delivery and monitoring, leading to enhanced reliability and efficiency in data storage devices, with improved yield and reduced sensitivity to wavelength variations.
Implementation Method 1
The implementation of a multi-mode interference (MMI) device within the waveguide structure, which simplifies fabrication, enhances tolerance to wavelength uncertainties, and reduces space occupancy, by efficiently splitting and recombining light
Implementation Method 2
Light from the waveguide is coupled in to the NFT. The NFT couples light into the media at a spot size smaller than the optical diffraction limit, heating a region of the media
Implementation Method 3
The NFT couples light into the media at a spot size smaller than the optical diffraction limit
Implementation Method 4
The light travels through the waveguide toward the ABS and is split between the arms of the waveguide
Data Source
AI summary
A heat-assisted magnetic recording (HAMR) write apparatus includes a laser for providing energy and resides in proximity to a media during use. The HAMR write apparatus includes a write pole that writes to a region of the media, coil(s) for energizing the write pole and a waveguide optically coupled with the laser. The waveguide includes at least one multi-mode interference (MMI) device. The MMI device has at least one input, a plurality of outputs, a propagation section and a multi-mode interference (MMI) section. Energy from the laser propagates through the propagation section before the MMI section. The propagation section expands the energy from the laser to a plurality of modes. A first portion of the outputs is output from the propagation section. The MMI section is between the propagation section and a second portion of the plurality of outputs.