Optical Waveguide Grating for Loss Inspection
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Solution Overview
Problem
Existing optical waveguide devices face challenges in easily specifying locations of optical losses such as propagation and coupling losses, particularly due to increased width of optical waveguides and complex light wave propagation paths, which complicates inspection and reduces the feasibility of reducing substrate size and minimizing propagation loss.
Innovation Solution
Incorporating a grating within the optical waveguide or connected to a monitoring waveguide that allows for inputting or outputting light waves through the grating, enabling easier inspection of optical losses and facilitating the use of a spot size converter to manage mode field diameter changes, while avoiding the need for high-surface-accuracy mirrors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical waveguide width is increased to match the optical fiber core diameter (10 μm), then the connection between optical waveguide and optical fiber is improved, but the substrate size cannot be reduced and propagation loss increases in U-turn waveguides
Solution Approach 1:
The patent changes the width parameter of the optical waveguide from the conventional 10 μm to a narrower width (e.g., 1 μm or less). This parameter change allows the optical waveguide to be folded on the substrate while reducing substrate size, though it creates a mode field diameter mismatch with optical fibers that requires a spot size converter to resolve.
2Area of stationary object
If the optical waveguide width is narrowed to approximately 1 μm to reduce substrate size, then the substrate size and propagation loss are reduced, but the mode field diameter mismatch with optical fiber increases connection loss
Solution Approach 1:
The patent introduces a spot size converter (SSC) as an intermediary component between the narrow optical waveguide (1 μm or less) and the optical fiber. The SSC gradually transforms the mode field diameter from the narrow waveguide width to the larger optical fiber core diameter, enabling efficient light coupling while maintaining the benefits of the narrow waveguide structure.
Solution Approach 2:
The spot size converter performs a gradual parameter change in the mode field diameter of the light wave as it propagates through the SSC. The waveguide width is gradually increased from the narrow waveguide width (1 μm or less) to a wider width that matches the optical fiber core diameter, transforming the mode field diameter accordingly to minimize connection loss.
3Area of stationary object
If a folded optical waveguide is formed to dispose input and output ports at the same end of the substrate, then the package size is reduced, but the propagation loss in U-turn waveguides increases
Solution Approach 1:
The patent changes the waveguide width parameter in the U-turn portion of the folded optical waveguide to a narrower width (1 μm or less). This parameter change reduces propagation loss in the U-turn waveguide by minimizing mode field distortion and scattering, while the folded configuration maintains the compact package size with input and output ports at the same end.
4Area of stationary object
If the optical waveguide width is narrowed to 1 μm or less, then the optical waveguide can be folded to reduce substrate size, but the numerical aperture increases making mirror reflection impractical
Solution Approach 1:
The patent extracts and removes the mirror component from the optical waveguide device. Instead of using a mirror to reflect light in the U-turn portion, the patent uses a narrow optical waveguide (1 μm or less) that guides light through total internal reflection, eliminating the need for a mirror and avoiding the problems associated with high numerical aperture and large mirror size requirements.
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 allows for straightforward identification of optical losses within the optical waveguide device, simplifies the inspection process, and reduces the complexity of light wave propagation, thereby enhancing the ability to minimize substrate size and propagation losses.
Implementation Method 1
a grating 6 formed in a part of the optical waveguide 2 or a grating 6 connected to a monitoring optical waveguide 5 that merges with or branches from a part of the optical waveguide 2, in which inputting a light wave into the optical waveguide or outputting at least a part of the light wave propagating through the optical waveguide is performed through the grating
Data Source
AI summary
An optical waveguide device that enables a location in which an optical loss such as a propagation loss or a coupling loss occurs to be easily specified is provided. An optical waveguide device includes a substrate 1 on which an optical waveguide 2 is formed, and a grating 6 formed in a part of the optical waveguide 2 or a grating 6 connected to a monitoring optical waveguide 5 that merges with or branches from a part of the optical waveguide 2, in which inputting a light wave into the optical waveguide or outputting at least a part of the light wave propagating through the optical waveguide is performed through the grating 6.