Waveguide Photodetector With Tapered Absorption Layer for Bright Light
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing photoelectric detectors face challenges in maintaining bandwidth and responsivity performance under bright light conditions, as the increased light energy leads to a decrease in detector bandwidth and responsivity.
Innovation Solution
The photoelectric detector design includes a waveguide layer, an absorption layer located on or embedded within the waveguide layer, and a cladding material covering the waveguide and absorption layers. The absorption layer has a thinner end surface adjacent to the light incident surface, reducing light energy absorption and carrier concentration, which enhances the electric field strength and increases the bright light input threshold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the area of the PIN junction is reduced and the width of the intrinsic area is increased to reduce parasitic capacitance and increase bandwidth, then the bandwidth is improved, but the internal electric field is weakened and the transit time of photogenerated carriers is increased
Solution Approach 1:
The patent applies local quality by creating a non-uniform thickness profile in the absorption layer, where the thickness varies along the light propagation direction. The thinner end surface adjacent to the light incident surface reduces parasitic capacitance locally, while the thicker other portions maintain sufficient light absorption. This local variation in thickness allows the detector to achieve reduced parasitic capacitance without significantly compromising the internal electric field strength or increasing transit time.
2Loss of energy
If the width of the intrinsic area is increased to reduce parasitic capacitance, then the parasitic capacitance is reduced, but the internal electric field is weakened and the drift speed of photogenerated carriers is slowed down
Solution Approach 1:
The patent implements local quality by designing the absorption layer with different thicknesses at different locations. The thinner end surface reduces parasitic capacitance in the region where it most impacts performance, while the thicker other portions preserve the internal electric field strength where photogenerated carriers are primarily generated and collected. This spatially differentiated thickness profile allows simultaneous optimization of both parasitic capacitance reduction and electric field maintenance.
3Quantity of substance
If the incident light energy increases, then the number of photogenerated carriers increases, but the carriers accumulate in the PIN junction and weaken the drift electric field, further increasing the transit time
Solution Approach 1:
The patent applies local quality by creating a thickness gradient in the absorption layer that varies along the light propagation direction. The thinner end surface reduces the accumulation of photogenerated carriers in the high-light-intensity region, preventing excessive carrier buildup that would weaken the drift electric field. Meanwhile, the thicker other portions ensure sufficient absorption of incident light to generate adequate photogenerated carriers for detection, thus maintaining performance under varying light conditions.
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 design effectively reduces the impact of bright light on the detector's bandwidth and responsivity, thereby increasing the bright light input threshold and improving overall performance.
Implementation Method 1
Photoelectric detectors are devices that convert high-speed optical signals into electrical signals
Implementation Method 2
A waveguide layer is provided
Data Source
AI summary
The disclosure provides a photoelectric detector. The photoelectric detector includes a waveguide layer, an absorption layer, and a cladding material. The absorption layer is located on an upper surface of the waveguide layer or at least partially embedded in the waveguide layer. The cladding material covers top portions and side walls of the waveguide layer and the absorption layer. At least one end surface of the photoelectric detector is a light incident surface, and a thickness of an end surface of the absorption layer adjacent to the light incident surface is smaller than a thickness of other portions.