Multi-segment Electro-optic Devices with RF Delay Lines
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Solution Overview
Problem
Electro-optic modulators in communication systems face limitations in speed and power efficiency due to electrical transmission line RF loss, velocity mismatch, and increasing optical loss, especially as data transmission rates increase, leading to diminishing returns in modulator performance with longer lengths.
Innovation Solution
A multi-segment electro-optic device with a multi-layer interconnect substrate and photonic integrated circuit, where electrical RF drive signals are synchronized with optical signals using varying length metallic RF transmission lines to achieve higher phase shifts and maintain bandwidth, reducing RF loss and velocity mismatch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the length of the electro-optic modulator is increased to achieve higher phase shifts, then the phase shift capability is improved, but the electrical transmission line RF loss and optical loss increase leading to diminishing returns
Solution Approach 1:
The electro-optic modulator is divided into multiple shorter segments that are optically connected in series. Each segment receives a synchronized electrical drive signal through RF transmission lines with carefully controlled lengths. This segmentation allows the total phase shift to be the sum of individual segment phase shifts while each segment operates at optimal length to minimize RF and optical losses.
2Use of energy by moving object
If multiple modulating segments are incorporated to achieve higher phase shifts, then the phase shift capability is improved, but the bandwidth may be limited to that of a single segment
Solution Approach 1:
The electrical drive signals for multiple segments are pre-synchronized using RF transmission lines with specifically designed lengths before reaching the modulator segments. This preliminary synchronization ensures that all segments receive their drive signals at the correct timing relationships, enabling the combined output to maintain the full bandwidth of individual segments while achieving higher total phase shifts.
3Use of energy by moving object
If the length of RF transmission lines is increased to connect multiple segments, then the phase shift capability is improved, but the velocity mismatch between electrical and optical waves increases
Solution Approach 1:
Each RF transmission line connecting to a specific modulator segment is designed with a unique length tailored to that segment's position and optical path length. This local customization of transmission line characteristics ensures that electrical signals arrive at each segment with the precise timing needed to match the optical wave propagation, thereby minimizing velocity mismatch effects while maintaining high phase shift capability across all segments.
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 higher phase shifts and bandwidth while minimizing RF loss and maintaining high performance, achieving compact and efficient operation by synchronizing electrical and optical signals across multiple segments, thus overcoming speed limitations and power inefficiencies.
Implementation Method 1
metallic RF transmission lines being electrically connected to receive one of the electrical drive signals from a corresponding one of the electrical outputs of the electronic driver
Implementation Method 2
electro-optical modulation waveguide segments, each of the segments having a control metallic RF transmission line electrically connected to receive one of the electrical RF drive signals
Data Source
AI summary
An electro-optic device, such as an optical modulator, comprises: a driver for generating a plurality of identical time-synchronized copies of an input electrical signal, and a photonic integrated circuit, including an optical waveguide structure and a plurality of phase-modulating electro-optical modulator segments. Each one of the modulator segments configured to receive a respective one of the plurality of the copies of the input electrical signal. Instead of incorporating a required phase delay between the copies of the input electrical signal into the driver structure, a multi-layer interconnect substrate is provided that includes a plurality of insulating layers alternating with a plurality of conductive layers. The plurality of conductive layers are configured to include a plurality of delay lines, each one of the plurality of delay lines electrically coupled in between the driver and the photonic integrated circuit configured to transmit a respective one of the plurality of copies of the first input electrical signal.