Optical Waveguide Refractive Index Change Region
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Solution Overview
Problem
Existing optical waveguide and arrayed waveguide connections suffer from increased circuit size, complex circuit design, and manufacturing difficulties, as well as high insertion loss when light transitions between slab and arrayed waveguides.
Innovation Solution
The implementation of a grating in the slab waveguide with a refractive index change region between the slab and arrayed waveguides, optimized for constructive interference, reduces insertion loss by localizing light of specific wavelengths and maintaining a compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a transition region is disposed between slab waveguide and arrayed waveguide, then insertion loss is reduced, but circuit size is increased
Solution Approach 1:
The patent introduces a refractive index change region that extends in the vertical dimension (depth direction) rather than only in the horizontal propagation direction. This vertical extension allows the transition region to be compact in the planar circuit layout while still providing effective refractive index grading to reduce insertion loss.
Solution Approach 2:
The refractive index change region is localized at specific positions between the slab waveguide and arrayed waveguide, with the refractive index varying only in the vertical direction at these localized points. This localized approach reduces the overall circuit size while maintaining the insertion loss reduction function.
2Loss of energy
If a slope portion is disposed between slab waveguide and arrayed waveguide, then insertion loss is reduced, but circuit manufacturing becomes difficult
Solution Approach 1:
Instead of using a slope portion that requires complex geometric shaping, the patent changes the refractive index parameter vertically at localized positions. This parameter change approach is easier to manufacture using standard waveguide fabrication techniques while achieving the same insertion loss reduction effect.
3Loss of energy
If tapered shape and position of island-shaped region are optimized, then light concentration on arrayed waveguide is improved, but circuit design becomes difficult
Solution Approach 1:
The refractive index change region is segmented into multiple discrete regions with different refractive indices arranged in the vertical direction. This segmentation simplifies the design process by allowing independent optimization of each segment rather than requiring complex continuous optimization of tapered shapes and positions.
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 solution reduces insertion loss while maintaining a compact design and simplifying manufacturing, effectively localizing light of other wavelengths in the arrayed waveguide without increasing circuit size or complicating the design process.
Implementation Method 1
a grating is formed in a slab waveguide... a self-image of the grating is formed... constructive interference portion
Implementation Method 2
constructive interference portion of a self-image of the grating is formed
Implementation Method 3
a refractive index change region is formed between the slab waveguide and the arrayed waveguide... average value of the refractive index in a refractive index distribution is averagely increased
Data Source
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AI summary
This invention provides an optical waveguide which does not increase the circuit size, does not make difficult the circuit design and manufacturing, and can reduce insertion loss when light enters from a slab waveguide toward an arrayed waveguide or when the light enters from the arrayed waveguide toward the slab waveguide. This optical waveguide is provided with a slab waveguide 1 in which a grating GP or GA is formed, an arrayed waveguide 2 connected to a position where a constructive interference portion of a self-image of the grating GP or GA is formed, and a refractive index change region DV which is formed between the slab waveguide 1 and the arrayed waveguide 2, in which an average value of a refractive index in a refractive index distribution in a direction substantially vertical to a light propagation direction is averagely increased from the slab waveguide 1 toward the arrayed waveguide 2, and in which an average value of the refractive index in a refractive index distribution in a direction substantially parallel to the light propagation direction is increased at a central axis of the arrayed waveguide 2.