Programmable Microring Resonators for Coupling Regime Control
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Solution Overview
Problem
Microring modulators in silicon photonic integrated circuits are sensitive to the distance between the modulator and the bus waveguide, leading to coupling issues that affect performance metrics such as extinction ratio and bit error rate, due to overcoupling or undercoupling.
Innovation Solution
A semiconductor junction in the microring modulator is forward biased to control the coupling regime by adjusting the charge density, reducing the quality factor, and shifting the microring modulator towards an undercoupled regime, allowing for tuning of the coupling rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between the microring modulator and the bus waveguide is reduced to increase coupling rate, then the coupling efficiency is improved, but the optical loss inside the microring increases due to overcoupling
Solution Approach 1:
The patent implements dynamic control of the coupling regime by applying different bias voltages to the microring modulator. This allows the system to transition between undercoupled, critically coupled, and overcoupled states, enabling real-time optimization of the balance between coupling efficiency and optical loss based on operational requirements.
Solution Approach 2:
The invention changes the electrical bias parameter of the microring modulator to control the carrier density in the waveguide, which in turn controls the coupling rate. By adjusting the bias voltage, the system can dynamically modify the coupling regime to achieve optimal performance for different operating conditions.
2Loss of energy
If the distance between the microring modulator and the bus waveguide is increased to reduce optical loss, then the optical loss is reduced, but the coupling rate decreases due to undercoupling
Solution Approach 1:
The system uses dynamic biasing to adjust the coupling regime, allowing it to compensate for the reduced coupling rate by increasing the coupling strength through electrical control when the physical distance is increased for lower optical loss.
Solution Approach 2:
By changing the electrical bias parameter, the system can compensate for the decreased coupling rate resulting from increased distance, maintaining optimal coupling efficiency without requiring physical repositioning of the components.
3Productivity
If process deviations occur in fabrication, then manufacturing variability increases, but the coupling rate and optical loss are adversely affected
Solution Approach 1:
The patent implements a feedback mechanism where the system measures the actual coupling regime and bias voltage to achieve the desired critical coupling condition. This closed-loop control compensates for manufacturing variations by adjusting the bias voltage to achieve the target performance metric regardless of fabrication tolerances.
Solution Approach 2:
The invention uses electrical bias adjustment to compensate for process deviations in the physical dimensions and material properties of the microring modulator. By changing the bias parameter, the system can achieve consistent coupling performance across devices with varying manufacturing tolerances.
4Productivity
If the coupling rate is increased to improve signal transmission, then the transmission efficiency is improved, but the extinction ratio deteriorates due to overcoupling
Solution Approach 1:
The system dynamically adjusts the bias voltage to control the coupling regime, enabling real-time optimization of the trade-off between signal transmission efficiency and extinction ratio based on the specific operational requirements and signal conditions.
Solution Approach 2:
By changing the electrical bias parameter, the system can precisely control the coupling rate to achieve the optimal balance between transmission efficiency and extinction ratio, allowing dynamic adaptation to different signal conditions and requirements.
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 approach improves manufacturing yield and performance by ensuring consistent coupling, compensates for dispersion and baseline wandering, and allows for dynamic trade-offs between optical bandwidth and modulation speed.
Implementation Method 1
A semiconductor junction in the microring modulator is forward biased to control the coupling regime by adjusting the charge density, reducing the quality factor
Data Source
AI summary
Techniques for programmable microring resonators are disclosed. In an illustrative embodiment, microring resonator is coupled to a waveguide. Due to process variations, the coupling rate between the microring resonator and the waveguide can vary. In order to tune the coupling regime between the microring resonator and the waveguide, a diode that forms part of the microring resonator can be forward biased, increasing the free carrier density and absorbing some of the light in the microring resonator. The forward biased diode can be used for various applications, such as to control the quality factor of the microring resonator, control a chirp on the light, and/or impart a blueshift to the microresonator.