Segmented Traveling Wave Optical Modulators
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Solution Overview
Problem
Conventional traveling wave Mach Zehnder optical modulators are limited by frequency-dependent transmissivity and low-pass frequency response of the RF path, leading to increased propagation loss and modulation speed limitations, which can result in distorted optical signals and require impractical voltage supplies for pre-amplification.
Innovation Solution
The RF path is segmented, with an amplifier positioned between segments to amplify attenuated RF signals, reducing the required driving voltage and counteracting frequency-dependent transmissivity, thereby enhancing modulation speed without the need for high voltage supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the RF path length is extended to achieve higher modulation speeds, then the modulation speed is improved, but the propagation loss increases due to frequency-dependent transmissivity
Solution Approach 1:
The RF path is divided into multiple segments with amplifiers positioned between them. Each segment has a controlled length that balances modulation speed achievement with acceptable propagation loss, allowing the overall system to achieve high speeds without excessive total loss.
Solution Approach 2:
Amplifiers are introduced as intermediary components between RF path segments. These amplifiers actively compensate for the frequency-dependent transmissivity and propagation loss that would otherwise limit the extension of the RF path length needed for high-speed modulation.
2Reliability
If pre-amplification is applied to counteract frequency-dependent transmissivity, then the modulation performance is improved, but impractical voltage supplies are required
Solution Approach 1:
The amplification function is segmented and distributed along the RF path rather than requiring a single high-voltage pre-amplifier. Multiple lower-voltage amplifiers placed between RF segments achieve the necessary total amplification while using practical voltage supplies.
Solution Approach 2:
Amplification is applied at intermediate points along the RF path before signals undergo significant attenuation, rather than requiring high-voltage pre-amplification at the input. This preliminary action at distributed points achieves performance improvement with practical voltages.
3Speed
If the RF path is extended to accommodate higher frequency signals, then the modulation speed is improved, but the low-pass frequency response causes increased attenuation
Solution Approach 1:
The extended RF path is segmented into manageable sections, each optimized for the frequency range it handles. Amplifiers between segments compensate for the cumulative attenuation that would otherwise prevent high-frequency signal transmission over extended paths.
Solution Approach 2:
Amplifiers serve as intermediary components that actively counteract the low-pass frequency response effects. They restore signal levels at intermediate points, enabling the extended RF path to maintain signal integrity at high frequencies despite inherent attenuation.
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 configuration achieves higher modulation speeds, exceeding 20GHz, with reduced propagation loss and extended RF path lengths without compromising modulation speed, while minimizing voltage requirements.
Implementation Method 1
Conventional traveling wave Mach Zehnder optical modulators are limited by frequency-dependent transmissivity and low-pass frequency response of the RF path
Implementation Method 2
travelling wave Mach Zehnder optical modulators include electronic drivers configured to modulate optical signals with radiofrequency (RF) signals
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A segmented traveling wave Mach Zehnder optical modulator is described. The segmented traveling wave Mach Zehnder optical modulator may comprise two or more radio frequency (RF) segments, and each RF segment may be configured to support a modulating RF signal. The modulating RF signals may be configured to modulate an optical signal propagating along an optical path of the segmented traveling wave Mach Zehnder optical modulator. The RF modulating signal in the second RF segment may be generated by amplifying the modulating RF signal of the first RF segment, using an RF amplifier. The RF amplifier may be configured to amplify a band-pass spectral portion of the modulating RF signal.