Optical Sensing Device With Frustroconical Light Guide
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Solution Overview
Problem
Semiconductor photodetectors, such as P-I-N diode photodetectors, require low capacitance, leading to small aperture sizes that complicate optical alignment and tolerances in optical communication systems, especially with optical fibers.
Innovation Solution
An optical sensing device with a support structure that provides mechanical stability to the optical element, which can be separate or integral, manufactured at the wafer-scale using semiconductor techniques, featuring a light guide system with a frustroconical shape to enhance light collection and minimize signal losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aperture size is reduced to achieve low capacitance, then the capacitance requirement is met, but the optical alignment difficulty increases
Solution Approach 1:
The patent introduces a light guide structure that extends the optical path in the vertical dimension (z-axis), allowing light to be collected from a larger effective area while maintaining a small photodetector aperture. The light guide has a height greater than the aperture diameter, creating a three-dimensional light collection volume that improves alignment tolerance without increasing capacitance.
Solution Approach 2:
The light guide acts as an intermediary element between the optical fiber and the photodetector. It receives light from the optical fiber over a larger area and guides it to the small photodetector aperture, mediating the size mismatch and improving optical coupling efficiency while maintaining low capacitance.
2Reliability
If the aperture size is reduced to achieve low capacitance, then the capacitance requirement is met, but the optical tolerance becomes more stringent
Solution Approach 1:
By extending the light guide height in the vertical dimension, the patent creates a larger optical acceptance cone that is less sensitive to lateral misalignments. This dimensional extension provides manufacturing tolerance buffer without requiring tighter precision on the photodetector aperture itself.
Solution Approach 2:
The optical system is segmented into distinct functional components: the light guide structure for light collection and guidance, and the small photodetector aperture for signal detection. This segmentation allows the light guide to be optimized for tolerance while the photodetector maintains low capacitance.
3Reliability
If a small aperture is used to achieve low capacitance, then the capacitance requirement is met, but the light collection efficiency decreases
Solution Approach 1:
The light guide exploits the vertical dimension by having a height greater than the aperture diameter, creating a three-dimensional light collection volume. This allows photons to be collected from a larger effective area and guided to the small aperture, improving light collection efficiency without increasing capacitance.
Solution Approach 2:
The light guide employs curved surfaces (spherical or cylindrical) to focus and guide light efficiently toward the photodetector aperture. These curved geometries improve light coupling and reduce signal loss by directing more photons onto the small detection area.
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
Improves the structural reliability and optical performance of the sensing device, allowing for efficient light collection and transmission while maintaining mechanical stability, thus addressing the challenges of small aperture sizes and optical alignment.
Implementation Method 1
an optical element having a light-receiving surface and configured to direct light to the photodetector
Data Source
AI summary
The present disclosure provides a communication system, a sensing device, and a semiconductor device, among other things. One example of the disclosed sensing device includes a semiconductor die having a photodetector, an optical element optically coupled to and disposed on the photodetector, at least one support structure substantially surrounding the optical element, and a top metal portion disposed on the semiconductor die adjacent to but distanced away from the optical element and the at least one support structure.