Dual-APD Photodetector Layout for Temperature-Stable Detection
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Solution Overview
Problem
The characteristics of avalanche photodiodes (APDs), such as multiplication ratio and photon detection probability, are temperature-dependent, posing a challenge for stable operation across a wide temperature range.
Innovation Solution
A photodetector configuration that includes a first avalanche photodiode sensitive to incident light and a second avalanche photodiode with reduced current fluctuation, where one terminal of each is electrically connected and connected to different power supplies, allowing for reduced temperature dependence of APD characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single avalanche photodiode is used for light detection, then the device structure is simple, but the temperature dependence of characteristics cannot be reduced
Solution Approach 1:
The photodetector is divided into two functionally independent avalanche photodiodes: a first APD for light detection and a second APD for temperature compensation. This segmentation allows each component to perform its specific function optimally while working together to reduce overall temperature dependence.
Solution Approach 2:
The second avalanche photodiode acts as an intermediary element that measures temperature-induced changes and provides compensation signals. This intermediary component enables the system to counteract temperature effects without directly modifying the primary light detection function.
2Reliability
If temperature compensation circuits are added to reduce temperature dependence, then the temperature stability is improved, but the device complexity increases
Solution Approach 1:
A second avalanche photodiode with the same structure and characteristics as the first APD is used to create a reference copy. This copy experiences the same temperature effects but not the light signal, allowing temperature compensation through comparison without requiring complex external compensation circuits.
3Measurement precision
If the multiplication ratio of APD is increased to enhance sensitivity, then the photon detection capability is improved, but the temperature dependence of characteristics is exacerbated
Solution Approach 1:
The second avalanche photodiode provides temperature feedback by detecting temperature-induced changes in its characteristics. This feedback information is used to compensate for temperature effects on the first APD, allowing the system to maintain stable operation even at high multiplication ratios where temperature dependence would normally be problematic.
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 effectively minimizes temperature dependence of APD characteristics, enhancing stability and performance across varying temperatures.
Implementation Method 1
The APD is a photodiode in which the light detection sensitivity is enhanced by multiplying the signal charge generated by the photoelectric conversion of the light incident on the photoelectric conversion layer by using the avalanche breakdown.
Implementation Method 2
multiplying the signal charge generated by the photoelectric conversion of the light incident on the photoelectric conversion layer
Data Source
AI summary
A photodetector includes a first APD that is sensitive to incident light and a second APD through which a constant current flows regardless of the incident light. One terminal of the first APD is electrically connected to one terminal of the second APD, another terminal of the first APD and another terminal of the second APD are connected to different power supplies, respectively, and the one terminal of the first APD and the one terminal of the second APD are both anodes or cathodes.