Optical Transmitter Dither Feedback for Temperature-Stable Gain
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Solution Overview
Problem
The gain adjustment of driver amplifiers in optical transmitters is challenging due to temperature fluctuations, leading to instability in optical output, as conventional electrical signal-based control methods fail to stabilize the optical output effectively.
Innovation Solution
An optical transmitter design that includes a driver amplifier, an adder for a dither signal, an optical modulator, a detector, and a controller to stabilize the optical output by controlling the gain of the driver amplifier based on detected fluctuations in the dither signal, using an optical stage instead of an electrical stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain adjustment of driver amplifier is controlled using electrical signal in electric stage, then the adjustment can be performed, but the optical output cannot be stabilized due to temperature fluctuation
Solution Approach 1:
The patent replaces the electrical-stage feedback system with an optical-stage feedback system. Specifically, it uses optical signal detection instead of electrical signal detection to monitor the driver amplifier output, and applies feedback control in the optical domain rather than the electrical domain. This substitution eliminates temperature-induced drift because optical detection is less sensitive to temperature variations than electrical detection, thereby stabilizing the optical output while maintaining precise gain adjustment capability.
2Productivity
If high multi-level and high symbol rate are used to increase transmission capacity, then the information length per symbol and number of symbols per unit time increase, but the degree of difficulty in optimization adjustment increases and the number of adjustment points increases
Solution Approach 1:
The patent implements an automatic feedback control system that continuously monitors the optical output signal quality and automatically adjusts the driver amplifier gain and optical modulator parameters. This feedback mechanism eliminates the need for manual optimization adjustment of multiple parameters, thereby reducing adjustment complexity while enabling high multi-level and high symbol rate operation to maximize transmission capacity.
Solution Approach 2:
The system performs self-adjustment through automatic feedback control, where the optical transmitter automatically optimizes its own parameters without external intervention. This self-service capability allows the system to adapt to changing conditions and maintain optimal performance for high-capacity transmission modes, reducing the burden of manual adjustment despite the increased number of adjustment points required for high multi-level and high symbol rate operation.
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 ensures stable and highly accurate signal quality by maintaining a constant output amplitude of the driver amplifier, despite temperature variations, thereby enhancing the optical transmission performance.
Implementation Method 1
a driver amplifier that amplifies a high-frequency signal
Implementation Method 2
an optical modulator that modulates an optical signal according to the high-frequency signal
Implementation Method 3
a detector that detects a fluctuation level of the dither signal from the modulated optical signal
Data Source
AI summary
An optical transmitter includes a driver amplifier, a superimpose, an optical modulator, a detector and a controller. The driver amplifier amplifies a high-frequency signal. The addition processor adds a dither signal to the high-frequency signal amplified by the driver amplifier. The optical modulator modulates an optical signal according to the high-frequency signal to which the dither signal is added. The detector detects a fluctuation level of the dither signal from the modulated optical signal. The controller controls a gain of the driver amplifier that amplifies the high-frequency signal so that an output amplitude of the driver amplifier is constant based on the detected fluctuation level of the dither signal.