Digital Optical Modulator for nQAM Generation
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Solution Overview
Problem
High power consumption and cost associated with high-speed analog-to-digital (ADC) and digital-to-analog (DAC) converters, as well as linear RF drivers, impede the implementation of coherent optical transceivers in high-speed systems like 40 Gb/s and 100 Gb/s.
Innovation Solution
A digital optical modulator system that generates n-quadrature amplitude modulation (nQAM) without the need for DACs or linear RF drivers, utilizing segmented phase modulators and digital drivers to reduce power dissipation and cost, while maintaining high bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-speed ADC and DAC converters are used in coherent optical transceivers, then signal quality and modulation capability are improved, but power consumption and cost increase significantly
Solution Approach 1:
The patent extracts and eliminates the DAC component from the traditional coherent optical transceiver architecture. By using a digital modulator that directly accepts digital signals from the DSP, the system removes the need for DAC conversion, thereby significantly reducing power consumption and cost while maintaining signal quality through direct digital-to-optical modulation.
Solution Approach 2:
The patent replaces the electrical analog modulation mechanism (requiring DAC and linear RF drivers) with a digital optical modulation mechanism. The digital modulator uses digital signals to directly control optical phase and amplitude, substituting the mechanical/electrical conversion chain with a purely digital control path that eliminates power-intensive components.
2Manufacturing precision
If DACs and linear RF drivers are implemented, then modulation accuracy is improved, but device cost increases
Solution Approach 1:
The patent removes DACs and linear RF drivers from the system architecture. The digital modulator is designed to accept digital output directly from the DSP and perform modulation without requiring these expensive analog conversion components, thereby reducing device cost while achieving modulation accuracy through digital control of the optical carrier.
Solution Approach 2:
The patent replaces expensive, complex analog components (DACs and linear RF drivers) with a more economical digital modulator design. The digital modulator uses standard digital logic and optical components that are cheaper and more easily manufactured, achieving the required modulation accuracy without the high cost of precision analog conversion equipment.
3Reliability
If traditional modulator architecture with DACs is used, then signal fidelity is maintained, but bandwidth is limited by converter speed
Solution Approach 1:
The patent replaces the analog signal path with a digital signal path throughout the modulation process. The digital modulator accepts digital signals from the DSP and directly modulates the optical carrier without analog conversion, eliminating the bandwidth limitations imposed by DAC sampling rates and analog filter characteristics, thereby achieving higher bandwidth while maintaining signal fidelity through digital precision.
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
Significantly reduces power consumption and cost, enabling high-density multi-channel integration and increasing bandwidth by eliminating the need for power-intensive components, thus facilitating the use of coherent technology in high-speed optical systems.
Implementation Method 1
a modulator coupled to the optical signal input and the digital driver... modulating the optical signal using a digital electrical signal from a digital electrical signal processor
Data Source
AI summary
An optical transceiver comprising an optical signal input, a first modulation section coupled to the optical signal input, a second modulation section coupled to the optical signal input and positioned in serial with the first modulation section, wherein the first modulation section comprises a first digital electrical signal input, a first digital driver coupled to the first digital electrical signal input, and a first modulator coupled to the first digital driver, and wherein the second modulation section comprises a second digital electrical signal input, a second digital driver coupled to the second digital electrical signal input, and a second modulator coupled to the second digital driver, and an optical signal output coupled to the first modulation section and the second modulation section.