Optical Waveguide Terminator with Taper and Bend
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Solution Overview
Problem
Existing optical waveguide terminators struggle to effectively suppress unnecessary optical reflection, leading to potential unintentional oscillations due to limitations in taper width and curvature radius, which result in increased device size and reflection ratios greater than desired.
Innovation Solution
The implementation of a terminator structure that combines a taper portion with a bending structure portion at the optical waveguide's end, where the taper portion gradually reduces in width and the bending structure portion has a constant width, effectively changing the light confinement condition to minimize reflection by discharging light into the clad layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a taper portion is formed to reduce the width of the optical waveguide, then light confinement condition is weakened and optical reflection is suppressed, but the minimum width is limited by semiconductor process restrictions preventing sufficient reflection suppression
Solution Approach 1:
The terminator is divided into two distinct portions: a taper portion that gradually reduces waveguide width to transition from strong to weak light confinement, and a bending structure portion that provides additional reflection suppression. This segmentation allows each portion to perform its specific function optimally while overcoming the limitations of a single-structure approach.
Solution Approach 2:
The invention introduces a bending structure portion that adds a spatial dimension change to the terminator. By bending the waveguide in addition to tapering it, the light is discharged in a different direction, enhancing reflection suppression without being constrained by the minimum width restrictions of the semiconductor process.
2Object-generated harmful factors
If a spiral shape is formed at the forward end portion with appropriate curvature radius to generate bending loss, then optical reflection is suppressed, but the occupying space becomes large increasing device size
Solution Approach 1:
The bending structure portion uses a curved geometry to suppress optical reflection through bending loss. The curvature is optimized to achieve effective reflection suppression while maintaining a compact size, avoiding the need for large-radius spiral structures that would increase device footprint.
3Object-generated harmful factors
If the forward end portion is inclined with respect to the remaining part of the optical waveguide, then some optical reflection is suppressed, but reflection ratio remains greater than desired for laser resonator applications
Solution Approach 1:
The terminator is segmented into a taper portion that provides initial reflection suppression through inclination, and a bending structure portion that provides additional reflection suppression. This segmentation enables the achievement of sufficiently low reflection ratios required for reliable laser resonator operation, overcoming the limitations of a simple inclined structure.
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 significantly reduces the reflection ratio to negligible levels, preventing unintentional oscillations and allowing for a more compact device design by ensuring light is efficiently discharged without significant reflection.
Implementation Method 1
a weak condition of light confinement is generated, when the forward end portion is formed in the taper shape
Implementation Method 2
unnecessary optical reflection is suppressed in the optical waveguide
Data Source
AI summary
A first optical waveguide is formed on a semiconductor substrate in such a way that the first optical waveguide is surrounded by clad layers. An outside portion of the first optical waveguide is formed as a terminator, which includes a taper portion and a bending structure portion. The taper portion has a width, which is gradually reduced in a direction to a forward end of the first optical waveguide. The taper portion coverts a light confinement condition from a strong condition to a weak condition in the direction to the forward end of the first optical waveguide. The bending structure portion has an arc shape extending from an outside end of the taper portion on a plane parallel to a surface of the semiconductor substrate.