Serpentine Folded Optical Modulator for High-Bandwidth Low-Loss Operation
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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 higher frequencies, which restricts high-speed optical communication performance.
Innovation Solution
The modulator is designed with a serpentine path that folds optical waveguides into multiple electrooptical modulation segments, separated by bends, and interleaved electrode pairs connected to metal traces, reducing the length of the electrical transmission line relative to the optical waveguide, thereby minimizing signal losses and allowing higher modulation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electrical transmission line length is increased to achieve longer optical waveguide interaction, then the modulation efficiency is improved, but the signal losses increase at higher frequencies
Solution Approach 1:
The optical waveguide is divided into multiple serpentine segments that fold back and forth between the same pair of metal traces. This segmentation allows the optical path length to be extended while the electrical transmission line length remains short, as each serpentine segment reuses the same electrode region. The optical wave travels through multiple folded segments (e.g., 5-10 segments) between the same metal traces, achieving long interaction length without proportionally increasing electrical line length and associated losses.
Solution Approach 2:
The serpentine optical waveguide path is nested within the region defined by the metal traces, folding multiple times within the same spatial envelope. This nesting allows the optical path to be compacted into a small area while maintaining long interaction length, effectively placing multiple optical path lengths within the same electrical modulation region.
2Speed
If the modulation bandwidth is increased for high-speed communication, then the data transmission rate is improved, but the electrical transmission line losses become prohibitive
Solution Approach 1:
The serpentine configuration segments the optical path into multiple interaction regions between the same metal traces. This allows the electrical transmission line to remain short (low loss) while the optical wave experiences multiple modulation events along its serpentine path, enabling high bandwidth operation without prohibitive electrical line losses.
3Productivity
If the optical waveguide length is extended to improve modulation efficiency, then the device area increases, but the electrical transmission line losses increase
Solution Approach 1:
The optical waveguide is configured in a serpentine (curved/folded) path instead of a straight line. This curvature allows the waveguide to fold back and forth within a compact area, achieving long optical path length (for high modulation efficiency) while confining the entire structure within a small device footprint. The serpentine path efficiently packs the optical length into minimal planar area.
Solution Approach 2:
The serpentine configuration transforms the optical path from a one-dimensional straight line into a two-dimensional folded pattern. This dimensional transformation allows the optical waveguide to achieve long interaction length by utilizing both horizontal and vertical space, effectively packing more optical path length into the same device area without requiring proportional increases in linear dimensions.
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 reduced optical losses and maintained modulation efficiency, enhancing high-frequency optical communication capabilities.
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
Data Source
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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.