RF-over-Fiber Control Module for Stable Optical Signal
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Solution Overview
Problem
Existing RF-over-fiber systems require sophisticated control loops with two controlled variables to stabilize the phase and amplitude of modulated optical signals, increasing manufacturing costs.
Innovation Solution
A control module that generates a control signal for an electro-optic modulator by combining an RF signal source, an amplitude adjustment circuit, a DC signal source, and a control circuit, which adapts the voltage of the DC signal based on frequency parameters to achieve stable phase and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sophisticated control loop with two controlled variables is used to stabilize phase and amplitude, then stability of the modulated optical signal is improved, but device complexity and manufacturing costs increase
Solution Approach 1:
The patent extracts and eliminates one of the two controlled variables from the conventional control loop. By fixing the amplitude of the RF signal and only controlling the DC bias voltage, the system reduces the control loop from two controlled variables to one, thereby simplifying the device while maintaining signal stability through the remaining controlled parameter.
Solution Approach 2:
The patent changes the control parameter from amplitude modulation to DC bias voltage modulation. By controlling the DC bias voltage of the electro-optic modulator instead of controlling both RF amplitude and DC bias, the system achieves phase and amplitude stabilization with a simpler single-variable control loop, resolving the contradiction between stability and complexity.
2Reliability
If a sophisticated control loop with two controlled variables is used to stabilize phase and amplitude, then stability of the modulated optical signal is improved, but manufacturing costs increase
Solution Approach 1:
The patent removes one controlled variable (RF amplitude) from the manufacturing complexity, leaving only DC bias voltage control. This extraction reduces the number of components and control mechanisms needed, directly lowering manufacturing costs while preserving signal stability through the simplified control architecture.
Solution Approach 2:
By changing the control strategy to rely on DC bias voltage adjustment rather than dual-variable control, the patent reduces manufacturing complexity. The simpler control loop requires fewer precision components and less complex calibration processes, thereby reducing manufacturing costs while maintaining the required signal stability.
3Adaptability or versatility
If the electro-optic modulator is operated in a non-linear region to multiply frequency, then frequency multiplication is achieved, but control complexity increases
Solution Approach 1:
The patent extracts the frequency multiplication function from the control complexity by operating the electro-optic modulator in its non-linear region. By fixing the RF amplitude and controlling only the DC bias voltage, the system achieves frequency multiplication through the modulator's inherent non-linear characteristics rather than through complex active control, thereby reducing control loop complexity while maintaining versatility.
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 significantly reduces the complexity and manufacturing costs of the control module while ensuring stable phase and amplitude of the modulated optical signal, allowing for efficient RF-over-fiber transmission.
Implementation Method 1
an optical signal is generated and modulated with an RF signal by an electro-optic modulator, thereby obtaining a modulated optical signal
Implementation Method 2
a superposition circuit configured to superimpose the adjusted RF signal and the DC signal, thereby obtaining the control signal for the electro-optic modulator
Data Source
AI summary
A control apparatus for generating a control signal for an electro-optic modulator is described. The control apparatus includes an RF signal source being configured to generate a radio frequency (RF) signal. The control apparatus further includes an amplitude adjustment circuit being configured to adjust an amplitude of the RF signal, thereby obtaining an adjusted RF signal. The control apparatus further includes a DC signal source being configured to generate a direct current (DC) signal. The control apparatus further includes a superposition circuit being configured to superimpose the adjusted RF signal and the DC signal, thereby obtaining the control signal for the electro-optic modulator. The control apparatus further includes a control circuit, wherein the control circuit is configured to receive at least one frequency parameter associated with the electro-optic modulator. The at least one frequency parameter includes a frequency multiplication factor and/or a target modulation frequency. The control circuit is configured to control the DC signal source to adapt a voltage of the DC signal based on the at least one frequency parameter received. Further, an optical signal generator apparatus and an RF-over-fiber system are described.