Tilted Optical Waveguide Surface for Laser Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermally assisted magnetic recording heads experience laser emission instability and mode hopping due to the light incident surface being perpendicular to the laser light incident direction, leading to increased error rates and difficulties in achieving high-density recording.
Innovation Solution
The thermally assisted magnetic recording head design features a light incident surface of the optical waveguide at an angle less than 90 degrees relative to the laser light incident direction, specifically between 45° to 87°, which prevents laser light from reflecting back along the original path, thereby stabilizing laser emission and suppressing mode hopping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light incident surface is perpendicular to the laser light incident direction, then the optical coupling is simplified, but laser emission instability and mode hopping occur due to back-reflection
Solution Approach 1:
The patent applies asymmetry by tilting the light incident surface at a specific angle (e.g., 8 degrees) relative to the perpendicular direction. This asymmetric configuration prevents back-reflected light from returning to the laser cavity along the original path, thereby eliminating mode hopping and emission instability while maintaining manageable optical coupling through controlled geometry
Solution Approach 2:
The patent converts the harmful back-reflection effect into a beneficial configuration by designing the light incident surface angle to redirect reflected light away from the laser source. The reflection that would normally cause instability is now utilized to define a precise angular relationship that stabilizes laser operation
2Ease of operation
If the light incident surface is perpendicular to the laser light incident direction, then the alignment is easier, but mode hopping and increased error rates occur
Solution Approach 1:
The light incident surface is designed with an asymmetric tilt angle (e.g., 8 degrees) relative to the perpendicular alignment. This asymmetric design prevents back-reflection-induced mode hopping and reduces recording error rates, while the specific angle is chosen to balance alignment ease with performance requirements
3Quantity of substance
If the volume of recording bits is reduced to increase storage density, then storage capacity increases, but magnetic instability occurs due to superparamagnetic effect
Solution Approach 1:
The patent changes the temperature parameter locally at the recording bit position by using laser heating through the optical waveguide. This thermal parameter change temporarily reduces the coercivity of the magnetic medium, enabling stable writing of ultra-high density bits that would otherwise be unstable due to superparamagnetic effects at reduced volumes
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 design improves laser emission stability and reduces mode hopping, enhancing the capability for high-density magnetic recording by preventing back-reflection of laser light, thus lowering error rates.
Implementation Method 1
a portion of the laser light emitting from the laser 3 is reflected back along the original path, causing laser emission instability and mode hopping
Implementation Method 2
The magnetic head 4 includes an optical waveguide 40
Implementation Method 3
to reduce the coercive force of the medium by using laser heating during the process of magnetic recording
Implementation Method 4
thermally assisted magnetic recording (TAMR) technology, which is also known in the art as heat assisted magnetic recording (HAMR)
Data Source
AI summary
A thermally assisted magnetic recording head and a thermally assisted magnetic recording disk drive are disclosed. The thermally assisted magnetic recording head includes a slider body, a laser substrate, a laser and a magnetic head, wherein the laser substrate is provided on the slider body, the laser is provided on the laser substrate, and the magnetic head is provided at a front end of the slider body. The magnetic head includes an optical waveguide facing the laser. The angle between a light incident surface of the optical waveguide and an incident direction of a laser light incident on the optical waveguide is less than 90 degrees. The thermally assisted magnetic recording disk drive includes a plurality of magnetic disks and a magnetic head suspending frame. A front end of the magnetic head suspending frame is provided with the thermally assisted magnetic recording heads mentioned above.