Multi-Level Phase Shifting in Mach-Zehnder Modulator Arms
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Solution Overview
Problem
Existing optical modulators require external devices like digital-to-analog converters (DACs), attenuators, and digital signal processors (DSPs) for generating multi-level analog electrical driver signals, leading to high power consumption and a large footprint, which limits their efficiency and compactness in high-speed optical communication systems.
Innovation Solution
The use of two separate CMOS drivers with different voltage swings to drive a single Mach-Zehnder Interferometer (MZI) arm segment, generating multi-level phase shifts without a DAC, and employing a level shifter to produce high modulation voltages with low-input voltages, thereby increasing modulation depth and output data rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external devices like DACs, attenuators, and DSPs are used to generate multi-level analog electrical driver signals, then modulation precision and signal quality are improved, but power consumption and device footprint increase
Solution Approach 1:
The patent extracts and eliminates the need for external DACs, attenuators, and DSPs by implementing multi-level modulation functionality directly within the MZM device using multiple independent voltage-controlled phase shifters, each driven by separate digital signals. This integration removes unnecessary external components while maintaining modulation precision.
Solution Approach 2:
The MZM device is designed to perform multiple functions simultaneously: it acts as both the modulator and the multi-level signal generator by using multiple phase shifters that can be independently controlled by digital signals. This multi-functionality eliminates the need for separate external devices for signal generation and modulation.
2Measurement precision
If external devices like DACs, attenuators, and DSPs are used to generate multi-level analog electrical driver signals, then modulation precision and signal quality are improved, but power consumption increases
Solution Approach 1:
The patent removes power-hungry external devices (DACs, attenuators, DSPs) from the system architecture. By implementing multi-level modulation directly within the MZM using digital-controlled phase shifters, the system eliminates the need for these external components, thereby significantly reducing overall power consumption while maintaining modulation precision.
Solution Approach 2:
The MZM device serves itself by generating multi-level modulation signals internally through multiple voltage-controlled phase shifters that respond to separate digital signals. This self-service capability eliminates the need for external signal generation equipment, reducing power consumption while maintaining precise modulation control.
3Productivity
If multiple independent voltage-controlled phase shifters are used to generate multi-level phase shifts, then modulation depth and output data rate are improved, but device complexity increases
Solution Approach 1:
The patent divides the modulation function into multiple independent voltage-controlled phase shifters, each handling a specific portion of the multi-level signal generation. Each phase shifter is controlled by separate digital signals, allowing independent optimization and simplified control logic, which manages device complexity while enhancing output data rate.
Solution Approach 2:
The patent transitions from single-dimensional binary modulation to multi-dimensional multi-level phase modulation by introducing multiple phase shifters that operate in parallel. This dimensional expansion enables higher output data rates by encoding multiple bits per symbol while managing complexity through modular architecture.
4Device complexity
If multi-level phase shifting is implemented without external devices, then power consumption and footprint are reduced, but achieving high modulation depth becomes difficult
Solution Approach 1:
The patent segments the phase modulation function into multiple independent voltage-controlled phase shifters, each contributing to the overall multi-level phase shift. This segmentation allows each phase shifter to operate within optimal voltage ranges, achieving high cumulative modulation depth without requiring high voltages from a single device, thus maintaining compact footprint.
Solution Approach 2:
The patent combines the effects of multiple voltage-controlled phase shifters to achieve high overall modulation depth. By merging their individual phase shift contributions, the system attains deep modulation without requiring any single component to operate at high voltage, preserving device compactness while achieving the desired modulation depth.
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 reduces power consumption, footprint, and optical loss while enhancing performance by achieving higher modulation depth and output data rates without the need for external devices, making it suitable for advanced modulation formats like nQAM and DP-16QAM.
Implementation Method 1
a first CMOS driver and a second CMOS driver are coupled across a PN junction at a single MZI arm segment. The first CMOS driver generates a first binary voltage signal according to a first data stream. The second CMOS driver generates a second binary voltage signal according to a second data stream. The first and second CMOS drivers generate multi-level modulation voltages across the PN junction that induce multi-level phase shifts
Data Source
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AI summary
An apparatus comprising a first electrical driver configured to generate a first binary voltage signal according to first data, a second electrical driver configured to generate a second binary voltage signal according to second data, wherein the first data and the second data are different, and a first optical waveguide arm coupled to the first electrical driver and the second electrical driver, wherein the first optical waveguide arm is configured to shift a first phase of a first optical signal propagating along the first optical waveguide arm according to a first voltage difference between the first binary voltage signal and the second binary voltage signal to produce a first multi-level phase-shifted optical signal.