Gradient Index Waveguide for High Density Light Delivery
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Solution Overview
Problem
Existing heat-assisted magnetic recording technologies face challenges in efficiently delivering large amounts of light power to small optical spots on magnetic recording media, requiring innovative solutions for high areal density recording.
Innovation Solution
A waveguide structure with specific refractive index layers, including a core layer, assist layer, and cladding layers, is used to efficiently direct light from a light source into a near-field transducer, enhancing light delivery efficiency and alignment tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a near-field transducer with waveguide is used to achieve small confined hot spots, then light confinement and recording density are improved, but alignment precision and light delivery efficiency deteriorate
Solution Approach 1:
The patent applies parameter changes by modifying the refractive index distribution through the gradient index layer. This creates a gradual transition that expands the acceptance angle of the waveguide, thereby improving alignment tolerance without sacrificing light confinement. The refractive index parameters are specifically engineered to balance mode confinement with coupling efficiency.
Solution Approach 2:
The gradient index layer serves as an intermediary between the light source and the core layer. It acts as a transition zone that gradually adapts the light modes, making the system less sensitive to misalignment while maintaining effective light delivery to the near-field transducer.
2Loss of energy
If light is directed into a waveguide with tight mode profile, then light delivery efficiency is improved, but alignment tolerance deteriorates
Solution Approach 1:
The patent changes the refractive index parameter distribution by introducing a gradient index layer with gradually varying index values. This creates a broader mode acceptance profile that maintains high coupling efficiency while being more tolerant to vertical misalignment between the light source and waveguide.
Solution Approach 2:
The gradient index structure provides dynamic adaptation of light modes as they propagate through the layer. The varying refractive index continuously adjusts the mode profile, allowing the system to maintain efficiency across a range of alignment conditions rather than requiring precise fixed alignment.
3Productivity
If large amounts of light power are delivered to small optical spots, then areal density recording is improved, but light delivery complexity increases
Solution Approach 1:
The waveguide structure is segmented into multiple functional layers: cladding layers for confinement, a gradient index layer for mode transformation, and a core layer for light delivery. This segmentation allows each layer to perform a specific function, simplifying the overall design while achieving high light delivery efficiency to small spots.
Solution Approach 2:
The patent employs composite waveguide structures combining materials with different refractive index properties. The gradient index layer uses composite material design to achieve the desired index profile, enabling efficient light confinement and delivery without requiring complex external optical systems.
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
The described waveguide structure improves light delivery efficiency and alignment tolerance, enabling effective high areal density recording by confining light to a tight mode profile and maintaining high coupling efficiency even with vertical position variations.
Implementation Method 1
a gradient index layer positioned adjacent the first cladding layer
Implementation Method 2
a core layer positioned adjacent the assist layer, the core layer having an index of refraction, n1; and a second cladding layer, the second cladding layer having an index of refraction, n4, wherein n1 is greater than n2, n3, and n4
Data Source
AI summary
A waveguide that includes a first cladding layer, the first cladding layer having an index of refraction, n3; a gradient index layer positioned adjacent the first cladding layer; an assist layer positioned adjacent the gradient index layer, the assist layer having an index of refraction, n2; a core layer positioned adjacent the assist layer, the core layer having an index of refraction, n1; and a second cladding layer, the second cladding layer having an index of refraction, n4, wherein n1 is greater than n2, n3, and n4; and n2 is greater than n3 and n4.