Asymmetrical Spot-Size Converter for Reduced Coupling Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing spot-size converters, such as those described in Non-Patent Document 1, require advanced processing techniques and are prone to dimensional variations due to fine waveguide ends, which can lead to characteristic variations and manufacturing challenges.
Innovation Solution
A spot-size converter design featuring a support body with specific areas and mesa structures, including an embedding structure with refractive index layers, allows for optical transitions and mode field diameter changes in a lateral direction, enabling efficient light propagation and conversion without the need for fine photolithography or etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the waveguide end width is narrowed to achieve spot-size conversion, then the mode field diameter changes effectively, but the manufacturing precision deteriorates due to dimensional variations and requirement for advanced processing techniques
Solution Approach 1:
The waveguide structure is divided into multiple sections along the propagation direction: an input waveguide section, a spot-size conversion section with gradually varying width, and an output waveguide section. This segmentation allows each section to have optimized dimensions and characteristics, avoiding the need for extremely fine overall waveguide ends while achieving spot-size conversion through the intermediate section's gradual width variation.
Solution Approach 2:
Instead of achieving spot-size conversion solely through lateral width reduction at the waveguide end, the invention introduces longitudinal variation in the waveguide width along the propagation direction. The width changes gradually from the input to the output section, creating a tapered structure that enables mode field transformation without requiring extremely narrow final dimensions, thus improving manufacturability.
2Reliability
If the waveguide end width is narrowed to 160 nm to achieve spot-size conversion, then the mode field diameter changes effectively, but the reliability deteriorates due to characteristic variations from dimensional variations
Solution Approach 1:
The waveguide is segmented into multiple sections with different width characteristics. The input and output sections maintain larger, more stable dimensions, while only the intermediate conversion section exhibits gradual width variation. This segmentation isolates the critical dimensional variations to a non-critical region, improving overall device reliability and reducing sensitivity to manufacturing tolerances.
Solution Approach 2:
The waveguide width parameter is changed gradually along the propagation direction rather than maintaining a constant narrow width. This continuous parameter variation creates a smooth transition of the mode field, reducing abrupt changes and associated losses, while the larger average dimensions improve reliability by reducing sensitivity to dimensional variations.
3Ease of manufacture
If advanced processing techniques are used to manufacture fine waveguide ends, then the spot-size conversion is achieved, but the device complexity increases
Solution Approach 1:
The complex spot-size conversion function is achieved through a segmented waveguide structure with multiple sections having different width characteristics. This segmentation allows standard fabrication techniques to be used for each section, avoiding the need for single-step ultra-fine processing, while the overall structure remains relatively simple and易于制造.
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
The proposed design effectively converts spot size and reduces optical coupling loss, providing stable waveguiding and adjustable mode field diameters, while simplifying the manufacturing process by eliminating the need for precise fine etching techniques.
Implementation Method 1
an embedding structure that includes a first region and a second region in which a first side-surface and a second side-surface of the second part of the first mesa structure are respectively embedded
Implementation Method 2
The first part and the second part of the first mesa structure include a lower cladding region, a core region, and an upper cladding region
Data Source
AI summary
A spot-size converter includes: a support body that includes a main surface including a first to a fifth areas; a mesa structure that includes a first part on the first area and includes a second part on the second to the fourth areas; and an embedding structure that includes a first region and a second region in which a first and a second side-surfaces of the second part of the mesa structure are respectively embedded. The second part of the mesa structure includes a portion that has a width gradually decreasing in a direction from the third area toward the fifth area. The first region of the embedding structure extends along the first side-surface and terminates at one of the third and the fourth areas. The second region of the embedding structure extends along the second side-surface of the second part and is disposed on the fifth area.