Germanium-on-Silicon Photodetector Array for High-Speed High-Power Handling
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Solution Overview
Problem
Conventional photodetectors face a trade-off between high-speed operation and high saturation power, with most Germanium photodetectors limited to approximately 5 mW saturation power and 10 GHz bandwidth, making it difficult to achieve both high-speed and high-power handling capabilities.
Innovation Solution
A traveling-wave photodetector array (TWPDA) is developed using a Germanium-on-Silicon substrate with multiple cascaded Germanium photodetectors and an impedance-matched traveling-wave electrode, incorporating optical waveguide delay lines for velocity matching and a double metal layer design for ease of fabrication and integration, enabling high-bandwidth and high-power handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a photodetector is designed with small dimensions to achieve high speed operation, then the bandwidth is improved, but the saturation power decreases due to space charge effect
Solution Approach 1:
The photodetector is divided into multiple smaller photodetector elements arranged in an array, where each element has small dimensions for high-speed operation. The electrode arrangement collects electrical signals from multiple elements, combining their outputs to achieve both high bandwidth and high saturation power handling capability.
2Power
If the photodetector dimensions are increased to improve saturation power, then the power handling capability is improved, but the bandwidth decreases due to increased capacitance and carrier transit time
Solution Approach 1:
Instead of using a single large photodetector, the invention segments the active area into multiple small photodetector elements. Each element maintains small dimensions for low capacitance and fast response, while the collective array provides large total area for high saturation power handling.
3Device complexity
If a single photodetector is used to simplify the structure, then the device complexity is reduced, but the power handling capability is limited
Solution Approach 1:
Multiple photodetector elements are merged into a single integrated array structure with a common electrode arrangement. The electrical signals from individual elements are conducted and combined by the electrode arrangement, achieving high power handling while maintaining relatively simple fabrication processes.
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 TWPDA achieves a large operation bandwidth and high power handling capability, suitable for microwave photonics and optical communication systems, with successful demonstration of 10 Gb/s pseudo-random binary sequence data detection.
Implementation Method 1
each germanium-based photodetector configured to receive an optical signal and to generate an electrical signal in response to the received optical signal
Data Source
AI summary
According to embodiments of the present invention, a photodetector arrangement is provided. The photodetector arrangement includes a plurality of germanium-based photodetectors, each germanium-based photodetector configured to receive an optical signal and to generate an electrical signal in response to the received optical signal, and an electrode arrangement arranged to conduct the electrical signals.