Silicon Optical 90-Degree Hybrid Layout for Low Loss and Phase Error
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Solution Overview
Problem
Optical 90-degree hybrid circuits formed with silicon waveguides experience significant phase errors and optical losses due to processing errors and high refractive index contrast, making them less efficient compared to quartz-based circuits.
Innovation Solution
The design incorporates a non-crossing configuration for arm waveguides with bent waveguides, including arc or clothoid shapes, and offset curvatures to equalize optical path lengths and reduce phase errors, along with non-overlapping optical splitters and couplers to minimize re-coupling and radiation mode degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If silicon waveguides are used to reduce circuit size, then circuit integration is improved, but phase errors and optical losses increase due to high refractive index contrast and processing errors
Solution Approach 1:
The patent employs bent waveguides with arc-shaped or clothoid curve geometries instead of straight waveguides. This curvature design allows for compact circuit layout while carefully controlling the optical path lengths to maintain phase accuracy despite the high refractive index contrast in silicon waveguides
Solution Approach 2:
The patent optimizes key parameters including waveguide width, thickness, bend radius, and offset distances to precisely control optical path lengths. By adjusting these parameters, the design compensates for processing errors and minimizes phase errors while maintaining the compact silicon waveguide structure
2Measurement precision
If arm waveguides are made longer to achieve proper optical path length equality, then phase accuracy is improved, but optical loss increases
Solution Approach 1:
The patent uses bent waveguides with arc-shaped or clothoid curve geometries to achieve the required optical path lengths in a more compact configuration. This reduces the total waveguide length compared to straight waveguide designs while maintaining phase accuracy through careful geometric design
Solution Approach 2:
The patent transitions from straight one-dimensional waveguide paths to two-dimensional curved paths with controlled offsets. This dimensional change allows for precise optical path length control while minimizing the total propagation distance and associated losses
3Device complexity
If optical splitters and couplers are positioned closer to reduce device complexity, then manufacturing is improved, but re-coupling and radiation mode degradation occur
Solution Approach 1:
The patent applies different design considerations to different regions of the device. Optical splitters and couplers are positioned with specific spacing and offset distances from each other and from bent waveguide sections. This localized spatial arrangement prevents harmful re-coupling and radiation mode effects while maintaining overall device compactness
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 optical loss and phase errors, facilitating easier electronic and optical packaging while maintaining high-frequency performance in silicon waveguide-based optical 90-degree hybrid circuits.
Implementation Method 1
an optical 90-degree hybrid circuit formed of a silicon waveguide
Implementation Method 2
Two beams of light branched by the optical splitter 103 pass through arm waveguides 105 and 108 and are input into two optical couplers 109 and 110 which are first and second optical coupling unit. Two beams of light branched by the optical splitter 104 pass through arm waveguides 106 and 107 and are input into two optical couplers 109 and 110 which are the first and second optical coupling unit. The signal light and the local oscillation light input to the optical coupler 109 and the optical coupler 110 are multiplexed and interfered with each other
Data Source
AI summary
To provide an optical 90-degree hybrid formed of a silicon waveguide capable of suppressing an optical loss and a phase error, and facilitating electronic packaging and optical packaging. In the optical 90-degree hybrid circuit including two optical branching units facing each other and two optical coupling units facing away from each other, four arm waveguides are arranged including bent waveguides each of which guides an output light of the optical branching unit to the optical coupling unit, and is formed in a curved shape.