Edge-Emitting Laser Diode for TMR Head Near-Field Light
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Solution Overview
Problem
Current thermally-assisted magnetic recording heads face challenges in achieving high output power for near-field light and maintaining optical system functionality due to insufficient laser output from surface-emitting laser diodes and degradation from wavelength fluctuations in diffraction optical elements.
Innovation Solution
A thermally-assisted magnetic recording head with an edge-emitting laser diode disposed on the element-integration surface, utilizing a waveguide and plasmon antenna to generate near-field light without a diffraction optical element, ensuring stable output and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a surface-emitting laser diode is used as a light source in the element-integration surface, then the optical system construction is simplified and mass-productivity is improved, but the laser output power is insufficient for high-density recording
Solution Approach 1:
The patent changes the emission type parameter of the laser diode from surface-emitting to edge-emitting. Edge-emitting laser diodes inherently provide higher output power due to their waveguide structure and longer cavity length, while still being compatible with wafer-level integration processes, thus resolving the contradiction between productivity and power output.
2Measurement precision
If a diffraction optical element is used to guide light to the desired position, then light can be directed to the correct location, but the optical system becomes more complex and is sensitive to wavelength fluctuations
Solution Approach 1:
The patent removes the diffraction optical element from the optical system. Instead of using a diffraction grating or similar element to redirect light, the system relies on the inherent directionality of the edge-emitting laser diode and simple waveguide structures, thereby eliminating the complex diffraction element and its sensitivity to wavelength variations.
Solution Approach 2:
The patent introduces a waveguide as an intermediary structure to transport light from the edge-emitting laser diode to the plasmon antenna. The waveguide provides a controlled optical path that is less sensitive to wavelength fluctuations compared to diffraction-based methods, simplifying the overall optical system while maintaining positioning accuracy.
3Ease of manufacture
If the light source is disposed in the element-integration surface, then manufacturing productivity is improved, but achieving sufficient output power becomes difficult
Solution Approach 1:
The patent changes the geometry and emission characteristics of the laser diode by using an edge-emitting configuration instead of surface-emitting. This parameter change enables higher output power while maintaining compatibility with wafer-level integration, as edge-emitting diodes can be fabricated using standard semiconductor processes and provide the necessary power density for near-field light generation.
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 provides sufficient output power for high-density recording, stabilizes near-field light intensity, and maintains optical system functionality despite wavelength fluctuations, enhancing mass-productivity and recording density.
Implementation Method 1
a waveguide for transmitting a light emitted from the light source
Implementation Method 2
a plasmon antenna for generating near-field light by receiving the light transmitted through the waveguide
Data Source
AI summary
A thermally-assisted magnetic recording head is provided, in which a light source with a sufficient power is disposed in the element-integration surface to improve mass-productivity. The head comprises, in an element-integration surface of a substrate: a light source; a waveguide for propagating light from the light source; and a magnetic pole for generating write field. Further, the edge along optical axis of the light source is set to be parallel with or inclined from the edge on the opposed-to-medium surface side of the element-integration surface. In the head, since the light source is disposed in the element-integration surface, the construction of the optical system can be completed in the stage of a wafer process. This construction can be relatively facilitated and simplified; thus, mass-productivity in the head manufacturing can be improved. Further, a light source with a sufficient power (cavity length) can be disposed in the element-integration surface.