Thermo-Optic Phase Shifter Bias Circuit for Resistance Drift
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Solution Overview
Problem
Photonic integrated circuits face challenges in maintaining stable electrical bias to thermo-optic phase shifters (TOPS) due to resistance changes caused by aging and temperature fluctuations, affecting the reliability and accuracy of optical phase tuning.
Innovation Solution
Incorporating a resistor with a resistance (Rs) that matches the resistance of the thermo-optic phase shifter (RTOPS) in a voltage divider configuration, stabilizing the power bias by selecting Rs such that the ratio |Rs-RTOPS| is less than or equal to about 0.2, thereby maintaining stable electrical power application despite resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed voltage source is applied to the TOPS, then the electrical power should be stable, but the resistance changes due to aging and temperature cause power instability
Solution Approach 1:
The patent implements a feedback mechanism by measuring the actual voltage across the TOPS and using this information to adjust the control voltage. The system continuously monitors the voltage division ratio and compensates for resistance changes by adjusting the control voltage accordingly, ensuring stable electrical power delivery despite TOPS resistance drift due to aging or temperature variations.
Solution Approach 2:
The patent introduces a series resistor as an intermediary element in the voltage division circuit. This resistor creates a voltage division relationship that can be measured and used to infer TOPS resistance changes. By measuring the voltage across the series resistor and using it as feedback, the system indirectly detects TOPS resistance variations and compensates for them, stabilizing the electrical power applied to the TOPS.
2Measurement precision
If the resistance of TOPS changes due to aging or temperature, then the optical phase tuning accuracy deteriorates, but increasing stabilization complexity increases device complexity
Solution Approach 1:
The patent makes the existing control voltage source perform multiple functions: it not only provides the control voltage for optical phase tuning but also serves as part of the sensing circuit for detecting TOPS resistance changes. The same voltage source and circuit elements are used for both actuation and sensing, eliminating the need for separate stabilization circuitry and maintaining optical phase tuning accuracy without significantly increasing device complexity.
Solution Approach 2:
The system uses its own operational parameters (the control voltage and resulting current) to detect and compensate for resistance changes. By monitoring the voltage division in its existing circuit during normal operation, the system self-diagnoses resistance drift and self-corrects by adjusting its control voltage, maintaining optical phase tuning accuracy without requiring external calibration equipment or complex additional stabilization mechanisms.
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 solution ensures that the electrical power applied to the TOPS remains stable, with changes less than 0.3% even when the resistance changes by up to 10%, thus enhancing the reliability and accuracy of optical phase tuning.
Implementation Method 1
the resistive heater is configured to generate heat when electrical power is applied thereto, wherein a heating temperature of the resistive heater increases with application of increasing electrical power
Implementation Method 2
a thermo-optic phase shifter (TOPS) configured to change a first phase of light entering the optical input to a second phase for light exiting the optical output, the TOPS in thermal communication with the waveguide
Data Source
AI summary
In part, the disclosure relates to opto-electrical system. The system may include a waveguide defining an optical input and an optical output; a thermo-optic phase shifter (TOPS) that includes a first electrical contact and a second electrical contact, and a resistive heater in electrical communication with the first electrical contact and the second electrical contact, the TOPS configured to change a first phase of light entering the optical input to a second phase for light exiting the optical output, the TOPS having a resistance RTOPS, the TOPS in thermal communication with the waveguide; a voltage source in electrical communication with the first electrical contact; and a resistor that includes a first end and a second end, the resistor having a resistance RS, wherein the first end is grounded, wherein the second end is in electrical communication with the second electrical contact.