Optical Modulator QAM-N Direct Drive Architecture
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Solution Overview
Problem
Conventional optical QAM schemes face significant optical loss and practicality issues due to the use of nested Mach-Zehnder in-phase modulators and ring resonator modulations, which are not suitable for commercial products due to high sensitivity to environmental conditions and fabrication tolerances.
Innovation Solution
An optoelectronic device comprising an input waveguide, two intermediate waveguides with modulating components connected in series to phase shifting components, and an output waveguide, which enables QAM-N modulation without the need for digital-to-analogue converters, reducing power consumption and requiring simpler driver signals, and includes a DC phase shifting intermediate waveguide to re-centre the constellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nested Mach-Zehnder in-phase modulators are used to achieve optical QAM schemes, then QAM modulation capability is improved, but optical loss increases significantly due to multiple 3-dB couplers and insertion loss
Solution Approach 1:
The patent extracts and eliminates the nested Mach-Zehnder interferometer structure and its associated 3-dB couplers from the system. Instead, it uses a simplified single-MZM configuration with direct drive electronics that can generate QAM-N modulation without requiring multiple coupling stages, thereby removing the source of cumulative optical loss.
Solution Approach 2:
The patent changes the modulation approach from using multiple 3-dB couplers in series to using a single modulator with directly driven QAM-N capable electronics. This parameter change in the modulation architecture reduces the number of coupling interfaces and eliminates cumulative insertion loss while maintaining QAM capability.
2Adaptability or versatility
If ring resonator modulations are used to implement QAM-16 modulation scheme, then modulation capability is improved, but device complexity and power consumption increase due to high sensitivity to environmental conditions requiring power intensive stabilization circuits
Solution Approach 1:
The patent removes the ring resonator structure and its associated environmental sensitivities from the system. By using a standard single-MZM configuration with direct drive electronics, it eliminates the need for complex stabilization circuits that would be required to compensate for environmental variations in ring resonator systems.
Solution Approach 2:
The patent replaces the complex, environment-sensitive ring resonator system with a simpler, more robust single-MZM approach. The new system uses straightforward electronic drivers that can be easily implemented without requiring expensive and complex stabilization mechanisms, making the solution more practical for commercial applications.
3Adaptability or versatility
If multiple 3-dB couplers are used in cascade to achieve QAM modulation, then modulation capability is improved, but total optical loss increases due to accumulation of insertion loss from each coupler
Solution Approach 1:
The patent extracts and removes the cascade of 3-dB couplers from the optical path. By using a single modulator with direct drive electronics capable of QAM-N modulation, it eliminates the need for multiple coupling stages, thereby removing the source of cumulative optical loss while preserving full QAM capability.
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 enables efficient QAM-N modulation with lower power consumption and simpler driver signals, overcoming the limitations of conventional devices by maintaining high integration density and reducing the need for stabilization circuits, thus providing a more practical and efficient modulation scheme.
Implementation Method 1
each intermediate waveguide includes a modulating component connected in series with a phase shifting component
Implementation Method 2
each intermediate waveguide includes a modulating component connected in series with a phase shifting component
Implementation Method 3
two intermediate waveguides, each coupled to the input waveguide via an input coupler; and an output waveguide, coupled to each of the intermediate waveguides via an output coupler
Data Source
AI summary
An optical device. In some embodiments, the device comprises: an input waveguide, configured to receive light; a first electro-absorption modulator, coupled to receive light from the input waveguide, and operable to produce a first output or a second output, wherein the second output has a lower amplitude than the first output; a second electro-absorption modulator, coupled to receive light from the input waveguide, and operable to produce a third output or a fourth output, wherein the fourth output has a lower amplitude than the third output; and an output waveguide, coupled to receive light from the first electro-absorption modulator and the second electro-absorption modulator, and output a combined signal comprising an output of the first electro-absorption modulator and an output of the second electro-absorption modulator.