Bolometer and Resistive Sensor Arrangement for HAMR Slider
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Solution Overview
Problem
Heat-assisted magnetic recording (HAMR) systems face challenges in accurately monitoring laser power and detecting contact at multiple close points without additional electrical bond pads, which are costly and complex, and suffer from mode hopping due to temperature variations affecting laser diode performance.
Innovation Solution
A sensor arrangement within the slider that includes a bolometer and resistive sensors, where the bolometer absorbs light from the optical waveguide to monitor laser power and a reference sensor compensates for thermal background, allowing for accurate detection of contact and power fluctuations using only two electrical bond pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional electrical bond pads are used to monitor laser power and detect contact at multiple close points, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple sensing functions (laser power monitoring, contact detection at multiple close points) into a single integrated sensor arrangement that uses only two electrical bond pads. The sensor arrangement includes a bolometer for optical power detection and resistive sensors for contact detection, all interconnected to share the two bond pads, thereby reducing device complexity while maintaining measurement precision.
Solution Approach 2:
The sensor arrangement is designed to perform multiple functions simultaneously using the same hardware components. The bolometer and resistive sensors serve dual purposes: monitoring laser power, detecting contact at multiple close points, and providing feedback for control, all through the shared two-bond-pad interface, making the system multi-functional without requiring separate dedicated pads for each function.
2Measurement precision
If additional electrical bond pads are used to monitor laser power and detect contact at multiple close points, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines multiple sensing functions (laser power monitoring, contact detection at multiple close points) into a single integrated sensor arrangement that uses only two electrical bond pads. The sensor arrangement includes a bolometer for optical power detection and resistive sensors for contact detection, all interconnected to share the two bond pads, thereby reducing device complexity while maintaining measurement precision.
3Device complexity
If laser diode operates without temperature compensation, then device complexity is reduced, but reliability deteriorates due to mode hopping
Solution Approach 1:
The patent implements a feedback mechanism where the bolometer continuously monitors laser power and the resistive sensors monitor contact conditions, providing real-time temperature and power information back to the control system. This feedback enables dynamic adjustment of laser diode operation to compensate for temperature variations and prevent mode hopping, improving reliability without requiring complex temperature compensation hardware.
Solution Approach 2:
The patent replaces complex mechanical temperature compensation systems with an optical-thermal sensing approach. Instead of using mechanical thermostats or active cooling mechanisms, the system uses bolometric and resistive sensors to detect temperature and power changes, converting thermal information into electrical signals for control, thereby simplifying the overall system while maintaining reliability.
4Measurement precision
If bolometer is placed in the optical waveguide path, then laser power monitoring accuracy is improved, but light path efficiency decreases
Solution Approach 1:
The patent applies local quality by placing the bolometer at a specific location within the optical waveguide where it can effectively monitor laser power with minimal interference to the overall light path. The bolometer is positioned to intercept a portion of the optical energy for sensing while the majority of the light continues through the waveguide, balancing measurement accuracy with energy transmission efficiency.
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 solution provides improved signal-to-noise ratio for laser power monitoring and contact detection at multiple close points, reducing the need for extra bond pads and minimizing light path efficiency impact, thereby stabilizing laser output and preventing mode hopping.
Implementation Method 1
A bolometer is situated at a location within the slider that receives at least some of the light communicated along the optical waveguide
Implementation Method 2
A first resistive sensor is configured to sense for spacing changes and contact between the slider and a magnetic recording medium at or near a first close point of the slider
Implementation Method 3
an optical waveguide configured to receive light from a laser source
Data Source
AI summary
A slider of a heat-assisted magnetic recording head comprises an air bearing surface and an optical waveguide configured to receive light from a laser source. The slider comprises a plurality of electrical bond pads including a first bond pad and a second bond pad. A first resistive sensor is configured to sense for spacing changes and contact between the slider and a magnetic recording medium at or near a first close point of the slider. A second resistive sensor is configured to sense for spacing changes and contact between the slider and the medium at or near a second close point of the slider. A bolometer is situated at a location within the slider that receives at least some of the light communicated along the optical waveguide. The first resistive sensor, the second resistive sensor, and the bolometer are coupled together and between the first and second bond pads.