Folded Optical Modulator With Serpentine Waveguide for High Bandwidth
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Solution Overview
Problem
Existing guided-wave optical modulators face limitations in modulation bandwidth due to increasing losses in the electrical transmission line at high frequencies, which restricts their performance without significantly increasing optical insertion loss.
Innovation Solution
The modulator is designed with a serpentine path that folds the optical waveguide into multiple electrooptical modulation segments, separated by bends, and uses interleaved electrode pairs to reduce the length of the electrical transmission line relative to the optical waveguide, allowing higher modulation frequencies with reduced signal loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrical transmission line length is increased to match the optical waveguide length, then modulation efficiency is improved, but signal loss increases at high frequencies
Solution Approach 1:
The optical waveguide is divided into multiple discrete electrooptical modulation segments separated by bends in the serpentine path. Each segment can be independently modulated by electrode pairs, allowing the system to achieve high modulation efficiency with shorter electrical transmission line sections, thereby reducing signal loss at high frequencies while maintaining effective modulation across the entire optical path.
2Productivity
If the optical waveguide length is increased to improve modulation bandwidth, then modulation bandwidth is improved, but optical insertion loss increases
Solution Approach 1:
The optical waveguide transitions from a straight configuration to a serpentine path that folds back on itself, effectively utilizing two-dimensional space to achieve a longer optical path length within a compact footprint. This dimensional transformation allows the waveguide to provide extended modulation bandwidth through increased interaction length with the electrodes while maintaining low optical insertion loss by optimizing the serpentine geometry to minimize bending losses and maintain mode confinement.
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 design achieves increased modulation bandwidth up to 100 GHz with maintained high modulation efficiency and low optical losses, enhancing the performance of optical modulators in communication systems.
Implementation Method 1
An electrical traveling microwave signal is coupled to the electrodes to modulate, through the electro-optical effect, the relative optical phase between the guided waves propagating through the respective branches
Implementation Method 2
In a guided-wave optical modulator which is configured as a Mach-Zehnder interferometer, a waveguide is split into two branches
Implementation Method 3
As the two branches of the waveguide are re-joined and the optical waves from the branches interfere with each other, the modulation of the relative optical phase is converted into a modulation of the amplitude of the combined optical wave
Data Source
AI summary
An optical device includes a substrate, at least first and second metal traces disposed on the substrate to define an electrical transmission line, and an optical waveguide, which is disposed on the substrate along a serpentine path passing between the metal traces, and which includes at least first and second electrooptical modulation segments, which are arranged in series along the optical waveguide between the first and second metal traces and are separated by bends in the serpentine path. The device further includes a plurality of electrode pairs, each electrode pair including first and second electrodes connected respectively to the first and second metal traces and disposed in mutual proximity on opposing sides of one of the electrooptical modulation segments, including at least first electrode pairs disposed on opposing sides of the first electrooptical modulation segment and second electrode pairs disposed on opposing sides of the second electrooptical modulation segment.