Optical Waveguide Device with Segmented Low Refractive Index Layer
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Solution Overview
Problem
The existing optical waveguide devices face challenges in size reduction due to large bending radii and significant insertion loss when using micro-optical waveguides with mode field diameters smaller than those of optical fibers, leading to peeling or cracking of low refractive index layers when their width is narrowed.
Innovation Solution
The optical waveguide device features a protuberant portion on the substrate with a low refractive index layer covering the optical waveguide, increasing the contact area and adhesion, and forming recess portions to enhance anchoring effects, preventing peeling even at narrow widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the width of the low refractive index layer is narrowed to reduce device size, then the device size is reduced, but peeling of the low refractive index layer occurs
Solution Approach 1:
The invention divides the low refractive index layer into multiple sections along the light propagation direction, with different widths in different sections. The wider sections provide enhanced adhesion to prevent peeling, while the narrower sections reduce overall device size. This segmentation allows the structure to simultaneously achieve size reduction and maintain bonding strength.
Solution Approach 2:
The invention applies different width characteristics to different locations of the low refractive index layer. Specifically, the layer has a first width in a first section and a second width (different from the first width) in a second section. This local variation in geometry allows optimization of adhesion in critical areas while maintaining compact overall dimensions.
2Volume of moving object
If a micro-optical waveguide with small mode field diameter is used to achieve size reduction, then the bending radius is reduced, but significant insertion loss occurs when directly joining with optical fiber
Solution Approach 1:
The invention changes the geometric parameters of the low refractive index layer, specifically varying its width along the light propagation direction. This parameter variation creates a gradual transition in the optical mode field diameter, enabling efficient coupling between the micro-optical waveguide and the optical fiber while minimizing insertion loss.
Solution Approach 2:
The invention addresses the coupling problem by introducing a dimensional variation in the low refractive index layer width. This creates a transition region that bridges the mode field diameter mismatch between the micro-waveguide and optical fiber, effectively solving the insertion loss issue through geometric dimensioning in the transverse direction.
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 effectively suppresses peeling of the low refractive index layer, allowing for reduced size and improved mechanical strength, enabling efficient optical modulation and transmission while maintaining low insertion loss.
Implementation Method 1
A low refractive index layer 2 (a permanent resist, a Si2 layer, or the like) is disposed to cover the optical waveguide 10. The low refractive index layer 2 has a lower refractive index than the optical waveguide 10 and is formed of a transparent material. Thus, an effect of suppressing scattering of a light wave caused by degradation of a surface of the rib type waveguide is expected.
Implementation Method 2
LiNbO3 (hereinafter, referred to as LN) having an electro-optic effect has small distortion and a low optical loss in converting an electrical signal into an optical signal
Data Source
AI summary
An optical waveguide device includes an optical waveguide formed on a substrate, in which a protuberant portion is formed on a surface of the substrate, the optical waveguide is disposed on the protuberant portion and is formed to have a larger width than a width of a part of the protuberant portion, and a low refractive index layer is disposed to cover the optical waveguide and to be in contact with at least a part of the protuberant portion, and has a lower refractive index than the optical waveguide.