Electro-optic Modulator with Tapered Electrode Spacing
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Solution Overview
Problem
Existing optical modulators face limitations in high-frequency performance due to propagation loss of RF electrodes, which restricts the modulation strength and efficiency, especially as higher frequency microwave signals are required for data transmission.
Innovation Solution
The optical modulator design features a waveguide with varying effective electro-optic modulation strength along its length, achieved by tapering the electrode spacing or widths, which allows for a monotonic decrease in effective modulation strength, optimizing high-frequency modulation efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electrode spacing is reduced to increase modulation strength, then modulation efficiency is improved, but propagation loss of RF electrodes increases
Solution Approach 1:
The patent applies local quality by making the electrode spacing non-uniform along the waveguide length. The spacing is smallest (providing highest modulation strength) at the input end where the RF signal is strongest, and gradually increases toward the output end. This local variation optimizes the balance between modulation strength and propagation loss at different positions along the device.
Solution Approach 2:
The patent implements a dynamic structure where the electrode spacing varies continuously along the waveguide length. This dynamic geometry allows the modulation strength to be optimized at each position according to the local RF signal strength, which decreases along the propagation direction due to attenuation.
2Productivity
If electrode spacing is reduced to improve modulation efficiency, then bandwidth is increased, but high-frequency performance deteriorates due to propagation loss
Solution Approach 1:
The patent applies local quality by making the electrode spacing non-uniform along the waveguide length. The spacing is smallest (providing highest modulation strength) at the input end where the RF signal is strongest, and gradually increases toward the output end. This local variation optimizes the balance between modulation strength and propagation loss at different positions along the device.
3Ease of manufacture
If modulator geometry is kept static to simplify manufacturing, then device complexity is reduced, but high-frequency performance cannot be optimized
Solution Approach 1:
The patent applies parameter changes by varying the geometric parameter (electrode spacing) continuously along the waveguide length. This creates a tapered structure where the spacing parameter changes from a minimum value at the input to a maximum value at the output, optimizing high-frequency performance while maintaining manufacturability through standard fabrication techniques.
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 enhances high-frequency modulation performance by concentrating high-frequency modulation at the region of maximum effective modulation strength before signal attenuation, thereby improving modulation efficiency and bandwidth while maintaining low optical losses.
Implementation Method 1
The electric field generated by the electrical signal in the electrodes (also termed 'electrode signal') changes the index of refraction of an electro-optic material that carries the optical signal
Data Source
AI summary
An electro-optic modulator including a waveguide and electrodes is described. The waveguide has a length proximate to at least a portion of the electrodes. Each electrode of the at least the portion of the electrodes is a traveling wave electrode and has an effective electro-optic modulation strength disposed along a length of the waveguide. The effective electro-optic modulation strength varies along the length of the waveguide.