Optical Waveguide Inclined Surface Reduces Coupling Loss
Solution Overview
Problem
Conventional Planar Lightwave Circuits (PLCs) experience optical coupling loss due to light reflection at the bond interface between the light emitting elements and the substrate, leading to energy inefficiency and potential damage to the light emitting diodes.
Innovation Solution
The optical device features an optical waveguide with inclined surfaces at its light incident and exit surfaces, angled relative to the substrate, which reduces light reflection attenuation and coupling loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the end portion of the optical waveguide is flush with the end portion of the substrate, then the manufacturing is simple, but light reflection occurs at the bond interface causing optical coupling loss
Solution Approach 1:
The patent introduces an inclined surface at the light incident surface of the optical waveguide, transitioning from a flush (2D plane) configuration to an angled (3D dimensional) configuration. This dimensional change redirects reflected light away from the bond interface, reducing optical coupling loss while maintaining manufacturing feasibility through standard polishing or etching processes.
Solution Approach 2:
The patent converts the harmful effect of light reflection at the bond interface into a beneficial outcome by using the inclined surface to deliberately reflect light in a controlled manner. The inclination angle is designed to redirect reflected light away from the light emitting element, transforming what would be damaging reflected light into a harmless or even useful directional reflection that reduces coupling loss.
2Device complexity
If the end portion of the optical waveguide is flush with the end portion of the substrate, then the structure is simple, but multiple reflections may damage the light emitting element
Solution Approach 1:
By introducing the inclined surface, the patent adds a dimensional feature to the otherwise simple flush structure. This additional dimension provides a geometric solution to prevent multiple reflections from returning to the light emitting element, enhancing reliability without requiring complex protective mechanisms or additional components.
3Loss of energy
If an inclined surface is introduced at the light incident surface, then optical coupling loss is reduced, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the geometric parameter of the light incident surface from a flat (0-degree inclination) to an inclined surface with a specific angle. This parameter change optimizes optical performance by reducing coupling loss, while the manufacturing complexity increase is mitigated by using standard fabrication techniques such as angled polishing, etching, or coating processes that can be integrated into existing production lines.
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 design effectively minimizes light reflection and coupling loss, enhancing energy efficiency and reducing the risk of damage to light emitting diodes by optimizing the interface geometry.
Implementation Method 1
a portion of the light is likely to be reflected at a bond interface, and multiple reflections and returned light may damage the LD, resulting an optical coupling loss
Data Source
AI summary
An optical device includes: a substrate having a pair of main surfaces opposite each other in a first direction and an end surface adjacent to the main surface, and an optical waveguide formed on the substrate and having a light incident surface or a light exit surface in a direction of a plane where the end surface is located, where at least a central portion of the light incident surface and/or light exit surface of the optical waveguide includes an inclined surface having a preset angle with respect to the end surface of the substrate.