HAMR Waveguide Alignment Using Assistant Cores
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Solution Overview
Problem
Conventional methods for aligning laser diodes with waveguides in HAMR disk drives often result in misalignments, leading to inadequate light emission and reduced performance due to fiducial mark inaccuracies and laser diode shifting during bonding.
Innovation Solution
The use of assistant cores with output devices to measure light intensity and calculate alignment offsets, allowing for precise alignment of the laser emission exit with the waveguide entrance before and after bonding, using methods such as center of mass calculations and linear regression models.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If fiducial marks are used to align the laser diode with the waveguide, then the alignment process is simplified, but misalignment occurs due to fiducial mark inaccuracies and laser diode shifting during bonding
Solution Approach 1:
The patent measures light delivery offsets from the laser emission exit to the waveguide entrance before bonding the laser diode to the slider. This preliminary measurement allows alignment parameters to be determined in advance, compensating for potential shifts during bonding and eliminating the need for fiducial marks.
Solution Approach 2:
The patent replaces the mechanical fiducial mark alignment system with an optical measurement system. By measuring light delivery offsets using the actual light path from the laser emission exit through the waveguide, the system achieves higher precision without relying on mechanical fiducial references.
2Stability of the object's composition
If the laser diode is bonded to the slider, then the components are permanently fixed, but misalignment occurs due to laser diode shifting during bonding
Solution Approach 1:
The offset measurement is performed before bonding, allowing the alignment state to be captured while the laser diode is still adjustable. This preliminary measurement enables compensation for any subsequent shifts during bonding by pre-determining the correct alignment parameters.
Solution Approach 2:
The measured offset information serves as feedback that is used to adjust the alignment of the laser emission exit with the waveguide entrance. This feedback loop ensures that even if shifting occurs during bonding, the final alignment can be corrected based on the preliminary measurements.
3Productivity
If the laser emission exit is not precisely aligned with the waveguide entrance, then the alignment process is faster, but light delivery is insufficient reducing HAMR disk drive performance
Solution Approach 1:
The patent replaces mechanical alignment methods with optical measurement methods. By measuring the actual light delivery path and offsets, the system ensures precise alignment and reliable light delivery without sacrificing productivity, as the measurement process is automated and efficient.
Solution Approach 2:
The system uses the laser's own emission to measure the alignment offset. By directing the laser emission through the waveguide and measuring the light delivery characteristics, the system performs self-diagnosis and self-alignment, ensuring reliable light delivery while maintaining efficient productivity.
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 enhances the alignment of the laser with the waveguide, improving the power delivery to the media and overall performance of HAMR disk drives by ensuring accurate light coupling and reducing misalignment issues.
Implementation Method 1
a laser provides energy used to heat the media for magnetic recording
Implementation Method 2
the laser provides energy used to heat the media
Implementation Method 3
The use of assistant cores with output devices to measure light intensity and calculate alignment offsets
Data Source
AI summary
A heat assisted magnetic recording (HAMR) transducer resides on a slider, has an air-bearing surface (ABS) and has a back side. The HAMR transducer includes a target waveguide, a plurality of assistant cores and a plurality of output devices. The target waveguide has an entrance at the back side and directs energy provided by a laser from the entrance at the back side toward the ABS. The assistant cores have a plurality of assistant core entrances at the back side. The assistant cores direct energy from the assistant core entrances to the output devices. In some aspects, the assistant cores and output devices may be used in aligning the laser and the target waveguide or checking the alignment of the laser and the target waveguide.