Thermally Assisted Magnetic Head Light Source Cavity Gap Control
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Solution Overview
Problem
Conventional thermally assisted magnetic heads with light source-mounting structures face challenges in manufacturing consistent gaps between the laser diode and the waveguide, leading to reduced usage efficiency of laser light due to increased emission part gaps, making it difficult to standardize all gaps to a preferred size.
Innovation Solution
The thermally assisted magnetic head incorporates a light source-cavity with a concave part larger than the sub-mount's mount bottom surface, allowing for the sub-mount to be inserted and joined, narrowing the gap between the laser diode and the light source-opposing surface, and using a classification method to adjust emission part gaps, thereby enhancing laser light usage efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light source is provided on the surface of the slider using conventional light source-mounting structure, then the structure is simpler, but the gap between the laser diode and waveguide becomes inconsistent and larger, reducing laser light usage efficiency
Solution Approach 1:
The sub-mount is inserted into a recess formed on the light source placing surface, creating a nested structure where the mounting substrate is partially embedded in the slider substrate. This nesting approach reduces the overall gap between the laser diode and waveguide while maintaining structural simplicity, as the recess provides precise positioning without requiring complex external mounting mechanisms.
Solution Approach 2:
The invention transitions from a surface-mounted configuration to a partially embedded configuration by forming a recess in the light source placing surface. This dimensional change allows the sub-mount to be positioned at multiple levels (surface and below), effectively reducing the vertical gap between the laser diode emission part and the waveguide entrance, thereby improving laser light coupling efficiency.
2Loss of energy
If the gap between laser diode and waveguide is reduced to improve laser light usage efficiency, then energy efficiency improves, but the manufacturing precision required increases to standardize all gaps
Solution Approach 1:
The recess is pre-formed on the light source placing surface during slider substrate manufacturing, establishing a predetermined mounting position before the actual laser diode assembly. This preliminary action ensures that all subsequent assemblies start from the same reference point, reducing variability in the final gap dimensions and lowering the overall manufacturing precision requirements.
Solution Approach 2:
The recess structure provides self-aligning and self-positioning functionality during assembly. The sub-mount naturally settles into the recess, which guides the laser diode into the correct position relative to the waveguide. This self-service mechanism reduces dependency on high-precision external alignment tools and processes, making gap standardization more achievable.
3Reliability
If the sub-mount is inserted into a recess larger than the mount bottom surface, then joining conditions become more stable and misalignment is reduced, but the structural complexity increases
Solution Approach 1:
The sub-mount is nested within a recess that is intentionally designed to be larger than the mount bottom surface, creating a partial embedding structure. This nesting provides stable joining conditions through increased contact area and mechanical interlocking, while the recess remains a simple geometric feature integrated into the slider substrate, avoiding excessive structural complexity.
Solution Approach 2:
The recess serves multiple functions simultaneously: it provides mechanical support for the sub-mount, establishes precise positioning, reduces the gap to the waveguide, and facilitates stable joining. By consolidating these functions into a single structural feature, the invention achieves improved reliability without proportionally increasing overall structural complexity.
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 reduces the emission part gaps, improving the usage efficiency of laser light by ensuring the laser diode is closer to the light source-opposing surface, even when sub-mounts with larger shift-sizes are used, thereby minimizing the current needed for heating and maintaining stable joining conditions.
Implementation Method 1
a laser diode 301 and a sub-mount 302 which the laser diode 301 is joined... laser light for generating the near-field light... The core layer 25 guides the laser light 149 from the light source-opposing surface 102 to the medium-opposing surface 101
Implementation Method 2
records data while instantaneously heating and thereby increasing the temperature of a portion of the magnetic recording medium where data will be recorded
Implementation Method 3
When light enters an opening smaller than the wavelength of light, the light slightly seeps from the opening and locally exists near the opening. The light locally existing near the opening is called near-field light. The near-field light is confined in a region much smaller than that of a spot light obtained by collecting light using a lens, so that use of the near-field light makes it possible to heat only a limited extremely small recording region of the magnetic recording medium
Implementation Method 4
The mount bottom surface 150a of the sub-mount 150 is inserted in the light source-cavity 161 to be joined to the light source-cavity 161
Data Source
AI summary
A thermally assisted magnetic head including a slider and a light source-unit. The slider includes a slider substrate and a magnetic head part. The light source-unit includes a laser diode and a sub-mount. The magnetic head part includes a medium-opposing surface, a light source-opposing surface and a waveguide which guides laser light from the light source-opposing surface to the medium-opposing surface. The slider substrate includes a light source-cavity formed in a light source-placing surface on which the light source-unit is placed. The light source-cavity includes an opening concave part being formed larger than a mount bottom surface of the sub-mount. The mount bottom surface of the sub-mount is inserted into the opening concave part to be joined to the light source-cavity.