Oblique Waveguide Facet Angle for Low Reflection Extraction
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Solution Overview
Problem
Existing waveguides for electro-optical components face challenges in achieving very low levels of reflection, particularly when the waveguide is not orthogonal to the facet, leading to light being reflected back into the waveguide instead of being extracted efficiently.
Innovation Solution
A waveguide design comprising a first part and a second part with a non-adiabatic longitudinal section and an obliquely cut surface, where the surface forms an angle between 5 and 80 degrees with the optical axis of the first part, ensuring that light exits at a sufficient angle to minimize reflection back into the waveguide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the waveguide is placed at a very high obliqueness angle to reduce reflection, then the reflection level is improved, but the chip width increases and manufacturing complexity increases
Solution Approach 1:
The patent optimizes the obliqueness angle parameter to a specific range (5-80 degrees) rather than using extremely high angles. This parameter optimization achieves low reflection levels while avoiding the negative consequences of excessive obliqueness such as increased chip width and manufacturing difficulty. The non-adiabatic longitudinal section is also positioned at specific distances from the exit surface to optimize the balance between reflection reduction and device compactness.
2Loss of energy
If the waveguide is terminated before the facet with a window region to spread light by diffraction, then reflection is reduced, but the device length increases
Solution Approach 1:
The waveguide is divided into distinct segments: a first part, a non-adiabatic longitudinal section, and a second part with an oblique exit surface. This segmentation allows each part to perform its specific function efficiently - guiding light, providing a transition section, and exiting light at an optimized angle - thereby reducing overall reflection without requiring excessive length.
Solution Approach 2:
The patent changes the geometric parameters of the waveguide sections, specifically the obliqueness angle of the exit surface (5-80 degrees) and the positioning of the non-adiabatic section, to achieve effective light extraction with minimized reflection while keeping the device compact.
3Device complexity
If the waveguide is abruptly interrupted to extract light, then the structure is simple, but reflection levels are high (approximately 30%)
Solution Approach 1:
The non-adiabatic longitudinal section is positioned before the oblique exit surface to pre-condition the light beam. This preliminary action prepares the light for the subsequent oblique exit by creating an appropriate beam profile and direction, thereby reducing reflection at the exit interface while maintaining structural simplicity.
Solution Approach 2:
The patent introduces a non-adiabatic longitudinal section with specific dimensional parameters (width and length ratios) to control the light beam characteristics before the oblique exit. This parameter optimization reduces the abruptness of the interruption, thereby reducing reflection while maintaining relative structural 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 design effectively reduces reflection back into the waveguide by refracting light at a large enough angle, ensuring that most of the light is extracted and not reflected back, thus achieving the required low levels of reflection.
Implementation Method 1
This design effectively reduces reflection back into the waveguide by refracting light at a large enough angle
Data Source
AI summary
A waveguide for the extraction of light at low levels of reflection arranged to guide light from an electro-optical component on a chip to a facet on the chip for extraction includes a first part and a second part. The first part (4) is extended, the second part (5) includes a surface (JK) through which the light exits from the waveguide (1). A non-adiabatic longitudinal section (GHLM) is located after the first part (4) but before the surface (JK) in the direction of propagation of the light, and the surface (JK) forms in the plane of the chip a first angle (V1) with the optical axis (A) of the first part (4) that lies between 5 and 80 degrees.