Abrupt Taper Waveguide for Light Sensor Sensitivity
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Solution Overview
Problem
Existing light sensors in optical devices face challenges in enhancing sensitivity and bandwidth due to the excitation of higher order modes, which leads to signal loss, and prior solutions involving long tapers do not effectively address these issues.
Innovation Solution
The implementation of an abrupt taper in the waveguide, where the width ratio between two locations is greater than 1.2:1 with a length less than 5 μm, 10 μm, or 50 μm, increases the sensitivity and bandwidth of the light sensor by preventing sufficient time for the light signal to move into the lower portion of the waveguide where sensitivity is reduced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a long taper is used in the waveguide to prevent higher order mode excitation, then signal loss is reduced, but the device length increases and sensitivity decreases
Solution Approach 1:
The patent changes the key parameter of the taper from a long, gradual transition to a short, abrupt transition with a width ratio greater than 1.2:1 and length less than 5-50 μm. This parameter change maintains effective single-mode operation while dramatically reducing the taper length, thereby resolving the contradiction between minimizing signal loss and reducing device length.
Solution Approach 2:
Instead of using a long taper to prevent higher order mode excitation, the patent inverts the approach by using a very short, abrupt taper that achieves the same effect through a rapid width transition. This inversion of the traditional gradual taper design resolves the contradiction by achieving mode control without the penalty of increased length.
2Measurement precision
If the waveguide width is reduced to improve light sensor sensitivity, then sensitivity increases, but higher order modes are more easily excited causing signal loss
Solution Approach 1:
The patent changes the taper geometry parameters (width ratio > 1.2:1, length < 5-50 μm) to create an abrupt transition that allows the waveguide to narrow quickly without exciting higher order modes. This enables the waveguide to achieve the narrow width needed for high sensor sensitivity while avoiding the signal loss that would normally result from higher order mode excitation.
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 abrupt taper design significantly enhances the sensitivity and bandwidth of the light sensor, reducing signal loss from higher order mode excitation, thereby improving the overall performance of the optical device.
Implementation Method 1
a light signal guided by the waveguide is received at the light sensor. The waveguide includes a taper configured such that a ratio of a width of the waveguide at a first location in the taper:the width of the waveguide at a second location in the taper is greater than 1.2:1 where a length of the taper between the first location and the second location is less than 5 μm, 10 μm, or 50 μm
Data Source
AI summary
The light sensor and waveguide are positioned on a base such that a light signal guided by the waveguide is received at the light sensor. The waveguide includes a taper configured such that a ratio of a width of the waveguide at a first location in the taper:the width of the waveguide at a second location in the taper is greater than 1.2:1 where a length of the taper between the first location and the second location is less than 60 μm.