EAMR Waveguide Light Sampling for Laser Power Monitoring
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Solution Overview
Problem
Conventional energy-assisted magnetic recording (EAMR) systems face challenges in accurately measuring laser power due to the large size of the EAMR assembly and poor correlation between light from the back and front of the light source, which affects mechanical and flyability requirements and optical feedback.
Innovation Solution
An EAMR head with a light source mounted on a sub-mount attached to a slider, featuring a waveguide that routes a portion of the light beam to a light detector positioned on the same side as the light source, allowing for precise monitoring of the light power emitted by the laser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light detector is positioned to sample light from the back side of the light source, then the measurement can be implemented, but the EAMR assembly size increases and mechanical/flyability requirements are compromised
Solution Approach 1:
Instead of sampling light from the back side of the light source as in conventional designs, this patent inverts the approach by sampling light from the front side/output end of the light source. The light detector is positioned to receive light that has already passed through the waveguide, providing accurate measurement without requiring additional space behind the light source.
Solution Approach 2:
The patent combines the light sampling function with the existing waveguide structure. The waveguide serves dual purposes: directing light to the recording media and providing a pathway for sampling light to the detector. This integration eliminates the need for separate sampling optics and reduces overall assembly size.
2Measurement precision
If the light detector samples light from the back of the light source, then measurement is possible, but there is poor correlation between back and front light which affects measurement accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the light detector samples the actual light output from the waveguide and provides measurement data back to the control system. This closed-loop feedback ensures accurate correlation between measured light and actual light delivered to the recording media, improving both precision and reliability.
Solution Approach 2:
The waveguide acts as an intermediary element that the light passes through on its way to the recording media. By placing the detector to sample light after it has traversed the waveguide, the measurement directly reflects the actual light delivery conditions, ensuring accurate correlation between measurement and actual effect.
3Device complexity
If conventional EAMR assembly configuration is used, then structure is simple, but accurate laser power measurement cannot be achieved due to size and optical feedback issues
Solution Approach 1:
The waveguide structure is given multiple functions: it serves as the light delivery path to the recording media and simultaneously as the sampling path for the light detector. This multi-functionality allows accurate measurement to be achieved without adding separate complex sampling optics, maintaining structural simplicity while improving measurement precision.
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 enables accurate monitoring of the light power used for heating the recording media while maintaining a compact design, improving mechanical and flyability performance by ensuring the light sampled by the detector and used for heating come from the same output of the light source.
Implementation Method 1
Light from the laser is directed by a transducer positioned within the slider to a region of the media disk thereby heating the region
Implementation Method 2
The light detector is configured to receive a first portion of the light transmitted to the waveguide
Data Source
AI summary
Aspects of the present invention relate to energy-assisted magnetic recording (EAMR), an EAMR assembly, and methods for fabricating the same. In several embodiments, an EAMR head includes a sub-mount on a slider that has a waveguide configured to receive light from a light source attached to a surface of the sub-mount. The waveguide receives the light at a top surface of the slider and routes the light to be near an air bearing surface (ABS) of the slider where energy of the light can be used to heat up a spot on a recording media disk that is proximate the ABS. The waveguide also routes a portion of the light back to the top surface of the slider where the light exits the waveguide and is detected by a light detector located along the surface of the sub-mount.