HAMR Waveguide Mode Converter for Optical Efficiency
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Solution Overview
Problem
Conventional heat-assisted magnetic recording (HAMR) transducers face inefficiencies in delivering optical power due to misalignments, waveguide deformations, and nonuniformities, which affect the power delivered to the near-field transducer (NFT) and subsequently the magnetic media, particularly in interferometric tapered waveguides.
Innovation Solution
The implementation of a waveguide structure that includes a mode converter, a mode stripper, and an inverse tapered section to efficiently isolate and suppress higher-order modes, ensuring that only the fundamental mode is coupled into the NFT, thereby enhancing optical efficiency and reducing the impact of misalignments and deformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an interferometric tapered waveguide (ITWG) is used to split and recombine laser power in multiple arms, then the waveguide can distribute optical power across multiple channels, but misalignments and deformations cause phase and power variations that reduce power delivery efficiency to the NFT
Solution Approach 1:
The patent creates a reference waveguide arm that serves as a template or copy of the ideal waveguide structure. By comparing the test waveguide arm against this reference, the system can identify and correct for manufacturing variations, misalignments, and deformations that would otherwise cause phase and power variations reducing optical efficiency.
Solution Approach 2:
The patent replaces mechanical alignment adjustments with an optical field-based compensation mechanism. Instead of physically realigning waveguide arms to compensate for misalignments, the system uses optical field measurements and adjustments to achieve proper phase and power matching, thereby maintaining efficient power delivery despite manufacturing variations.
2Device complexity
If conventional waveguide structures are used without mode conversion and stripping, then the device complexity is reduced, but higher-order modes are not suppressed leading to degraded optical efficiency and unreliable power delivery
Solution Approach 1:
The patent implements mode conversion and mode stripping sections as preliminary processing stages before the main interferometric waveguide arms. These sections pre-condition the optical field by converting higher-order modes to the fundamental mode and stripping away unwanted modes, ensuring that only clean, well-defined modes enter the main waveguide structure. This preliminary action prevents mode-related reliability issues downstream.
Solution Approach 2:
The patent introduces mode converter and mode stripper sections as intermediary elements between the laser source and the main interferometric waveguide. These intermediaries serve as buffer zones that condition the optical field, converting and filtering modes before they can cause problems in the main waveguide arms, thereby improving reliability without significantly increasing overall device complexity.
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 optical efficiency of power delivery to the NFT, leading to enhanced performance and reliability of HAMR disk drives by maintaining desired phase and power differences in the interferometric waveguide, resulting in improved data writing capabilities.
Implementation Method 1
a mode converter, a mode stripper, and an inverse tapered section to efficiently isolate and suppress higher-order modes
Implementation Method 2
Light is provided from a laser to a waveguide in a HAMR transducer fabricated on a slider. The light travels through the waveguide toward the ABS and is coupled into a near-field transducer (NFT).
Implementation Method 3
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 4
heating a region of the media
Implementation Method 5
Light is provided from a laser to a waveguide in a HAMR transducer
Implementation Method 6
The light travels through the waveguide toward the ABS and is coupled into a near-field transducer (NFT)
Data Source
AI summary
A heat-assisted magnetic recording (HAMR) write apparatus includes a laser and has an air-bearing surface (ABS) that resides in proximity to a media during use. The HAMR write apparatus includes a write pole that writes to the media, coil(s) for energizing the write pole and a waveguide optically coupled with the laser. The waveguide includes an entrance distal from the ABS and a bottom proximate to the ABS. The waveguide also includes a mode converter, a mode stripper optically coupled with the mode converter and an inverse tapered section optically coupled with the mode stripper. The mode converter has sides converging from a first width proximate to the entrance to a second width distal from the entrance and less than the first width. The mode stripper is between the inverse tapered section and the mode converter. The inverse tapered section has an entrance and an exit wider than the entrance.