Waveguide Array Modulator for High-Power Linear RF Photonics
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Solution Overview
Problem
Integrated optical modulators in RF Photonic systems face limitations in optical power handling capability and linearity, which restrict the achievement of high spurious-free dynamic range (SFDR) required for high-performance systems.
Innovation Solution
A waveguide array modulator (WAM) is employed, comprising a parallel array of optical modulators driven by a single RF signal, allowing for high power level modulation through combined output power or using an array photodetector, and incorporating modulators with varying dynamic ranges to achieve high linearity and SFDR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single integrated optical modulator is used, then the device complexity is low, but the optical power handling capability is limited
Solution Approach 1:
The patent divides a single modulator into multiple parallel modulator elements (e.g., 4x2:0 modulator elements). Each element handles a portion of the total optical power, allowing the system to scale power handling capability by increasing the number of elements without proportionally increasing device complexity.
2Ease of manufacture
If a single integrated optical modulator is used, then the manufacturing cost is low, but the linearity and SFDR performance are limited
Solution Approach 1:
The patent uses multiple parallel modulator elements that can be independently optimized for linearity. By distributing the modulation function across multiple elements and combining their outputs, the system achieves higher overall linearity and SFDR performance while maintaining compatibility with standard CMOS fabrication processes.
3Power
If multiple parallel modulator elements are used to increase power handling, then the optical power handling capability increases, but the device complexity increases
Solution Approach 1:
The patent combines multiple modulator elements in parallel with their inputs and outputs merged. This allows the system to achieve higher power handling capability while maintaining a relatively simple structure where all elements share common control signals and are integrated within a unified device footprint.
4Reliability
If multiple parallel modulator elements are used to improve linearity, then the SFDR performance improves, but the manufacturing complexity increases
Solution Approach 1:
The patent designs the modulator elements to be identical and interchangeable, allowing them to be fabricated using standard CMOS processes. This universal design enables multiple elements to be manufactured simultaneously in parallel, improving linearity and SFDR without significantly increasing manufacturing complexity or cost.
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 WAM system overcomes the limitations of individual optical modulators by generating high power modulated signals, achieving equivalent performance to Lithium Niobate external modulators with improved cost-effectiveness and scalability, and extends the dynamic range of RF Photonic systems.
Implementation Method 1
A single electrical input is used to drive an array of two or more waveguide based optical modulators, providing multiple modulated outputs
Data Source
AI summary
In the Waveguide Array Modulator (WAM) a single electrical signal drives an array of waveguide optical modulators, creating multiple modulated output signals that can be combined to provide a higher output power than from a single waveguide based modulator, enabling a higher dynamic range system. Alternatively, using a WAM in which different waveguide optical modulators are designed for different dynamic ranges, e.g. one highly efficient modulator for low level signals and one low efficiency but linear modulator for high level signals, the WAM based system can provide a higher dynamic range than from a single waveguide based modulator. Various WAM based systems for different applications are included.