Silicon Nitride Waveguide Epitaxial Mold for Optical Coupling
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Solution Overview
Problem
Legacy optical couplers for silicon photonic chips face limitations in achieving efficient optical coupling due to restricted angles and curved reflective faces, leading to inconsistent signal reflection and higher optical loss.
Innovation Solution
The use of an epitaxially-grown silicon mold to form a silicon nitride waveguide with a reflective face angled greater than 50 degrees and a linear profile, enhancing reflection consistency and reducing optical loss by smoothing the reflective surface to less than 10 nanometers roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a legacy optical coupler uses a standard manufacturing process with grayscale lithographic etch in silicon oxide layer, then the manufacturing process is simple and achievable, but the reflective face angle is limited to approximately 45 degrees and the surface is curved, leading to inconsistent signal reflection
Solution Approach 1:
The patent changes the manufacturing parameter from grayscale lithographic etch to epitaxial growth process, enabling the formation of a (111) crystal plane with a steeper angle greater than 50 degrees. This parameter change in the manufacturing process allows achieving higher angular precision and a linear profile instead of a curved surface, directly resolving the contradiction between manufacturing precision and ease of manufacture.
2Reliability
If the reflective face has a curved profile from legacy manufacturing, then the manufacturing process is simpler, but the signal reflection is inconsistent and optical loss is higher
Solution Approach 1:
The patent changes the geometric parameter of the reflective face from a curved profile to a linear profile through epitaxial growth. This parameter change ensures consistent signal reflection by providing a uniform reflection angle across the entire reflective surface, thereby improving reliability and reducing optical energy loss that occurs with curved profiles.
3Productivity
If the reflective face roughness is not controlled, then the manufacturing process is faster and simpler, but the optical coupling efficiency is reduced due to higher optical loss
Solution Approach 1:
The epitaxial growth process inherently produces a smooth reflective face with less than 10 nanometers roughness without requiring additional smoothing steps. The crystal growth mechanism itself self-corrects surface irregularities, providing a naturally smooth surface that minimizes optical scattering and energy loss, thereby improving optical coupling efficiency while maintaining manufacturing simplicity.
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 approach enables more efficient optical coupling by improving the angle and smoothness of the reflective face, resulting in better directionality and reduced loss of optical signals, thus enhancing the overall performance of silicon photonic chips.
Implementation Method 1
the face and the surface of the silicon layer form an angle of greater than 50 degrees at the cavity... Through the use of an epitaxially-grown silicon mold
Implementation Method 2
When an optical signal travelling through the SiN waveguide encounters the cavity, the respective indices of refraction between the SiN waveguide and the cavity may cause the light to reflect
Data Source
AI summary
Embodiments may include or relate to an optical coupler. The optical coupler may include a silicon nitride (SiN) waveguide. The waveguide may be formed by placing SiN on an epitaxially grown silicon structure that is then removed subsequent to placement of the SiN. Other embodiments may be described and/or claimed.