Optical Device Light Sensor Horizontal Electrical Field
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Solution Overview
Problem
Optical and optoelectronic light sensors used in communications applications face challenges with high optical loss and undesirable dark current when used with larger waveguides, particularly due to the limitations of silicon as a light-absorbing medium.
Innovation Solution
An optical device with a light sensor featuring a light-absorbing medium that receives light signals from a waveguide, where an electrical field is generated parallel to the base, reducing dark current and enabling efficient operation with larger waveguide dimensions by using doped regions or electrical conductors as field sources, and incorporating a taper to reduce the light-absorbing medium's width for increased speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If sub-micron waveguide dimensions are used, then light sensor speed is adequate, but optical loss becomes unacceptably high
Solution Approach 1:
The patent changes the waveguide dimension parameter from sub-micron to larger dimensions (several microns), which resolves the optical loss problem while the horizontal electrical field configuration maintains adequate sensor speed performance
2Loss of energy
If larger waveguide dimensions are used, then optical loss is reduced, but light sensor speed decreases and dark current increases
Solution Approach 1:
The patent applies a horizontal electrical field configuration (changing the field orientation parameter) which enables larger waveguide dimensions to be used while maintaining light sensor speed and reducing dark current
Solution Approach 2:
The patent creates a localized horizontal electrical field in the light-absorbing medium that optimizes carrier collection efficiency, allowing larger waveguide dimensions without sacrificing speed or increasing dark current
3Loss of energy
If larger waveguide dimensions are used, then optical loss is reduced, but dark current becomes unacceptably high
Solution Approach 1:
The patent changes the electrical field orientation parameter to horizontal, which suppresses dark current generation mechanisms that would otherwise occur with larger waveguide dimensions, allowing reduced optical loss without accepting high dark current
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 solution reduces dark current and optical loss, allowing the light sensor to maintain desirable speed and performance even with larger waveguide sizes commonly used in communications applications.
Implementation Method 1
a light-absorbing medium configured to receive a light signal from the waveguide
Implementation Method 2
When the light-absorbing material absorbs a light signal, an electrical current flows through the light-absorbing material
Implementation Method 3
an application of a reverse bias across the doped regions forms an electrical field in the light-absorbing medium included in the ridge
Data Source
AI summary
The device includes an optical waveguide on a base. The waveguide is configured to guide a light signal through a light-transmitting medium. A light sensor is also positioned on the base. The light sensor including a ridge extending from slab regions. The slab regions are positioned on opposing sides of the ridge. A light-absorbing medium is positioned to receive at least a portion of the light signal from the light-transmitting medium included in the waveguide. The light-absorbing medium is included in the ridge and also in the slab regions. The light-absorbing medium includes doped regions positioned such that an application of a reverse bias across the doped regions forms an electrical field in the light-absorbing medium included in the ridge.