Silicon Photonics Waveguide Photo Detector with Split Signal Distribution
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Solution Overview
Problem
High bandwidth Photo Detectors (PD) designed for large input optical power face challenges in achieving optimal responsivity, bandwidth, and sensitivity, leading to poor Signal to Noise Ratio (SNR) and Bit Error Rate (BER) due to saturation and space charge non-linear responses.
Innovation Solution
A silicon photonics unit is designed with an input waveguide, a distribution unit that splits the input optical signal into two signals, and a photodetector with two optical input ports. This configuration allows for improved optical power absorption and reduced space charge distribution, enabling operation at higher optical powers with increased saturation current and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the PD's geometrical diameter and thickness are increased to receive larger optical power, then the saturation current increases, but the bandwidth decreases and dark current increases
Solution Approach 1:
The patent divides the single photodetector into multiple photodetectors (e.g., four photodetectors arranged in a 2x2 array). Each photodetector has smaller geometrical dimensions, maintaining high bandwidth and low dark current, while the collective array provides sufficient saturation current to handle large optical power inputs without saturation
Solution Approach 2:
The patent transitions from a single photodetector to a two-dimensional array of photodetectors. This spatial arrangement in multiple dimensions allows the system to achieve both high saturation current (through increased total detection area) and high bandwidth (through small individual detector dimensions) simultaneously
2Speed
If the PD's geometrical diameter and thickness are decreased to increase bandwidth, then the bandwidth increases, but the saturation current decreases and the device saturates at lower optical power
Solution Approach 1:
The patent segments the total detection function across multiple small photodetectors. Each photodetector maintains small dimensions for high bandwidth, while the parallel combination of multiple detectors provides the necessary total saturation current capacity
Solution Approach 2:
The patent combines the output signals from multiple photodetectors to achieve the required saturation current level. The individual high-bandwidth detectors are merged in parallel, preserving the bandwidth advantage while accumulating sufficient current handling capability
3Measurement precision
If the PD is designed for high sensitivity to detect low optical power, then the sensitivity increases, but the device becomes prone to saturation when receiving large optical power
Solution Approach 1:
The patent divides the optical signal detection across multiple photodetectors, each optimized for high sensitivity. The segmented architecture allows each detector to operate in its linear range even when the total optical power is high, preventing saturation while maintaining sensitivity
Solution Approach 2:
The patent changes the system parameter from single-detector area to multi-detector count. This parameter transformation allows the system to maintain high sensitivity (through optimized individual detector design) while expanding the total optical power handling range (through parallel detection channels)
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 proposed design enhances the detection of input optical signals by splitting the signal into two paths, which are fed to opposite sides of the photodetector, thereby improving responsivity, bandwidth, and sensitivity while maintaining high saturation current, thus addressing the limitations of existing PD designs.
Implementation Method 1
a photodetector (PD) that may include a PD's first optical input port, a PD's second input port, and an electrical PD output port; wherein the PD is configured to output, via the PD electrical output port, an output signal indicative of the first optical signal and the second optical signal
Data Source
AI summary
There may be provided a silicon photonics unit that may include an input waveguide that is configured to convey an input optical signal; a distribution unit (DU) that comprises a DU input port, a first DU output port, a second DU output port and a distribution core; wherein the distribution core is configured to receive the input optical signal, split the input optical signal to a first optical signal and a second optical signal, provide the first optical signal to the first DU output port and provide the second optical signal to the second DU output port; a photodetector (PD) that comprises a PD's first optical input port, a PD's second optical input port, and a PD's electrical output port; wherein the PD is configured to output, via the PD output port, a PD output signal indicative of the first optical signal and the second optical signal; a first optical path that comprises a first waveguide and is configured to convey the first optical signal to the PD's first optical input port; and a second optical path that comprises a second waveguide and is configured to convey the second optical signal to the PD's second optical input port.