Optical Modulator Phase Shifter Electrode Length Ratio
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Solution Overview
Problem
Conventional optical modulators face challenges in achieving equal signal level intervals while minimizing modulation loss and power consumption, often resulting in power penalties and increased modulation loss due to non-linear phase shift curves.
Innovation Solution
The optical modulator employs an encoder to adjust phase shift amounts on each arm of a Mach-Zehnder interferometer, using a specific electrode length ratio for phase shifters to ensure equal signal level intervals, thereby optimizing the linear part of the phase shift curve and reducing the number of phase shifters required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical modulators use standard phase shifter configurations, then the device structure is simple, but signal level intervals are unequal and modulation loss increases
Solution Approach 1:
The patent applies local quality by assigning different electrode lengths to different phase shifters in the Mach-Zehnder interferometer arms. Specifically, the first phase shifter has a first electrode length and the second phase shifter has a second electrode length, creating localized differences in phase shift characteristics to achieve equal signal level intervals. This targeted approach resolves the contradiction by modifying only the critical phase shifter parameters rather than redesigning the entire device.
Solution Approach 2:
The patent changes the physical parameter of electrode length for the phase shifters to control the phase shift amounts. By setting specific electrode length ratios (first electrode length/second electrode length), the system achieves equal signal level intervals. This parameter change approach allows precise control over the phase shift curve linearity, transforming the device performance without fundamentally altering its structure.
2Manufacturing precision
If more phase shifters are added to achieve equal signal levels, then signal level interval equality improves, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and utilizes only the essential phase shift control functionality needed to achieve equal signal levels. Instead of adding multiple phase shifters, the invention optimizes the electrode lengths of the existing phase shifters to extract the maximum phase shift control capability from each component, achieving the desired signal level equality with minimal additional elements.
Solution Approach 2:
The phase shifters in the patent serve multiple functions: they control phase shift amounts for different signal levels, enable equal interval spacing of symbol points, and optimize the linear region of the phase shift curve. By designing the electrode lengths to satisfy specific ratios, a single phase shifter configuration achieves multiple performance goals simultaneously, reducing the need for additional phase shifters.
3Loss of energy
If phase shift amounts are optimized for linear region, then modulation loss decreases, but the range of adjustable phase shifts is limited
Solution Approach 1:
The patent creates a dynamic phase shift control system where the electrode lengths are designed to provide optimal phase shift amounts for different signal levels. The first and second phase shifters can be independently controlled to achieve the desired phase shift while maintaining operation within the linear region of the phase shift curve, enabling dynamic adaptation to different modulation requirements without sacrificing linearity.
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 effectively suppresses modulation loss and power consumption while maintaining equal signal level intervals, improving the efficiency and performance of the optical modulator.
Implementation Method 1
an optical modulator including a Mach-Zehnder (MZ) interferometer... a first phase shifter group that is arranged on the first upper arm for each bit digit of a bit string of the data signal output from the encoder, and adjusts a phase shift amount of the first optical signal that passes through the first arm according to a bit value for each bit digit
Data Source
AI summary
An optical modulator includes: an encoder that encodes an input data signal; a branch circuit that branches an optical signal into first and second optical signals; a first arm through which the first optical signal branched at the branch circuit passes; a first phase shifter group on the first upper arm that adjusts a phase shift amount of the first optical signal that passes through the first arm; a second arm through which the second optical signal branched at the branch circuit passes; a second phase shifter group on the second arm that adjusts a phase shift amount of the second optical signal that passes through the second arm such that a sign of the phase shift amount of the second optical signal becomes opposite to a sign of the phase shift amount of the first optical signal; and a multiplexing circuit that multiplexes the first optical signal.