Mach-Zehnder Modulator Phase Control via Signal Polarity Inversion
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Solution Overview
Problem
Mach-Zehnder optical modulators face challenges in adjusting phase differences without increasing light propagation loss, which occurs when manufacturing variations in waveguide width and length cause deviations in phase difference, requiring longer electrodes or higher voltages.
Innovation Solution
An optical modulation apparatus with a Mach-Zehnder optical modulator, a phase adjustment circuit, a drive circuit, and a signal polarity reversal circuit that switches phase adjustment electrodes and reverses signal polarity to control phase differences between optical waveguides, thereby reducing the need for increased voltage or electrode length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the voltage applied to the electrodes is increased to adjust phase difference, then the phase adjustment capability is improved, but the propagation loss of light increases
Solution Approach 1:
Instead of applying high voltage to achieve phase adjustment, the invention applies low voltage and compensates by inverting the polarity of the modulation signal. This allows the system to achieve the same phase adjustment effect without the harmful side effect of increased propagation loss that occurs with high voltage application.
Solution Approach 2:
The invention changes the parameter of voltage from high to low, and compensates for the phase adjustment by changing the polarity parameter of the modulation signal. This parameter substitution allows phase adjustment to be achieved without increasing voltage, thereby avoiding increased propagation loss.
2Measurement precision
If the length of electrodes is increased to adjust phase difference, then the phase adjustment capability is improved, but the propagation loss of light increases
Solution Approach 1:
Rather than extending electrode length to increase phase adjustment capability, the invention uses polarity inversion of the modulation signal to achieve the same effect with shorter electrodes, thereby reducing propagation loss.
3Adaptability or versatility
If high voltage is applied to electrodes to compensate for manufacturing variations, then the phase adjustment range is improved, but the propagation loss increases
Solution Approach 1:
The invention achieves wide phase adjustment range not through high voltage but through polarity inversion of the modulation signal, maintaining adaptability while avoiding the propagation loss that would result from high voltage application.
Solution Approach 2:
The system compensates for manufacturing variations by changing the polarity parameter of the modulation signal rather than increasing voltage, achieving the required phase adjustment range without increasing propagation loss.
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 solution allows for precise phase adjustment while minimizing light propagation loss, ensuring accurate modulation and reducing the impact of manufacturing variations on phase difference.
Implementation Method 1
a voltage is applied to electrodes provided on the two optical waveguides, respectively, so that the phase adjustment is performed
Implementation Method 2
The Mach-Zehnder optical modulator is the optical modulator that turns on or off the light according to an interference condition at the time of multiplexing the lights
Data Source
AI summary
An optical modulation apparatus including: a Mach-Zehnder optical modulator having two optical waveguides, two output optical waveguides and a join-and-branch portion; a phase adjustment circuit configured to output a phase control signal to phase adjustment electrodes provided respectively on the two optical waveguides; a drive circuit configured to output a modulation signal to modulation electrodes provided respectively on the two optical waveguides as a differential signal, the modulation signal modulating lights propagated in the two optical waveguides; and a signal polarity reversal circuit configured to reverse a polarity of the differential signal to be output from the drive circuit.