Optical Waveguide Slit Formation via Dry Etching
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Solution Overview
Problem
High relative refractive-index difference in optical waveguides leads to increased optical loss and difficulty in forming slits due to varying etching rates of core and cladding materials, especially when using dry etching, which results in uneven slit depths and damage to surrounding waveguides.
Innovation Solution
A manufacturing method involving layering cladding and core materials on a substrate, forming the core into a waveguide shape, creating a gap for the slit, and using dry etching to form the slit while ensuring the same etching material is used for both cladding layers, thereby maintaining consistent depth and avoiding damage to adjacent waveguides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the relative refractive-index difference is increased to enable high-density integration, then the allowable minimum bend radius decreases and integration density increases, but the optical loss at the slit increases exponentially
Solution Approach 1:
The patent changes the material parameters of the cladding layer by doping silica glass with zirconia to achieve a refractive index of 1.455-1.465 at 1550 nm wavelength. This parameter change enables the cladding to have sufficient refractive index to support high relative refractive-index difference waveguides while reducing optical loss at slits through optimized material composition
2Ease of manufacture
If dry etching is used to form slits in high relative refractive-index difference waveguides, then slit formation is achieved, but the etching rates of core and cladding differ significantly causing uneven slit depths
Solution Approach 1:
The patent modifies the chemical composition parameters of the cladding layer by adding zirconia doping to silica glass, changing its etching rate characteristics. This parameter change reduces the etching rate difference between core and cladding materials during dry etching, enabling more uniform slit depth formation while maintaining the ability to form slits in high relative refractive-index difference waveguides
3Ease of manufacture
If a dicing saw is used to form slits, then slit formation is achieved, but unnecessary cuts are made in surrounding portions causing damage to other optical waveguides
Solution Approach 1:
The patent replaces the mechanical dicing saw system with a dry etching process. This substitution eliminates the physical contact and wide cutting path of the mechanical saw, allowing precise slit formation without damaging surrounding optical waveguides while maintaining ease of manufacture
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 method reduces optical loss and allows for precise slit formation without damaging surrounding optical waveguides, enabling stable light propagation and effective integration of wave plates in optical waveguide devices.
Implementation Method 1
when TE-polarized light (linearly polarized light having polarization direction parallel to a main surface of a substrate on which the cladding portion is formed) propagating through the optical waveguide is converted into TM-polarized light (linearly polarized light having a polarization direction perpendicular to TE-polarized light), a 1/2 wave plate is inserted into the slit
Data Source
AI summary
A manufacturing method of an optical waveguide device that allows light to propagate through a core formed within a cladding formed on a substrate, the core having a higher refractive index than the cladding, includes: layering a first cladding-material layer for the cladding and a core-material layer for the core sequentially on the substrate; forming the layered core-material layer into the core having a waveguide shape, and removing a first part of the core, the first part being positioned at a portion where a slit is to be formed, to thereby form a gap in the core; layering a second cladding-material layer for the cladding to cover the first cladding-material layer and the core; and removing, by dry-etching, a second part of the first and second cladding-material layers, the second part being positioned at the portion where the slit is to be formed, to thereby form the slit.