Differential Electro-Optic Modulator Waveguide Spacing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electro-optic differential modulators face challenges in achieving high modulation bandwidth and efficiency due to significant electrical series resistance and optical coupling between closely-spaced waveguides.
Innovation Solution
The implementation of a novel differential electro-optic modulator that reduces the physical distance between waveguides by removing the bias voltage connection between semiconductor junction diodes, while maintaining finite depletion regions, thereby reducing electrical resistance and enhancing modulation bandwidth and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the physical distance between waveguides is reduced to increase modulation bandwidth, then modulation bandwidth is improved, but optical coupling between waveguides increases causing detrimental effects
Solution Approach 1:
The patent introduces a semiconductor region as an intermediary material between the two optical waveguides. This semiconductor region with finite depletion regions acts as a mediator that allows close spacing for high bandwidth while managing the optical interaction between waveguides through its specific electrical and optical properties.
Solution Approach 2:
The patent changes the electrical parameters of the semiconductor region by maintaining finite depletion regions, which alters the optical properties of the intermediate material. This parameter change enables the semiconductor region to serve as an effective intermediary that reduces optical coupling while allowing close waveguide spacing.
2Loss of energy
If bias voltage connection is removed to reduce electrical series resistance, then electrical resistance is reduced improving modulation efficiency, but maintaining reverse-biased condition becomes more challenging
Solution Approach 1:
The semiconductor region with finite depletion regions serves itself to maintain the reverse-biased condition without requiring external bias voltage connections. The depletion regions inherently create the necessary electrical conditions to keep the waveguides reverse-biased, eliminating the need for additional biasing circuitry and reducing electrical series resistance.
3Area of stationary object
If waveguides are closely spaced to reduce device size, then device footprint is reduced, but optical coupling between waveguides increases
Solution Approach 1:
The semiconductor region acts as an intermediary that enables close spacing for compact device footprint while managing optical coupling. By positioning the semiconductor region with finite depletion regions between the waveguides, the design achieves small form factor without suffering from excessive optical coupling that would normally occur at such close distances.
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 approach results in significantly higher modulation bandwidth and efficiency by reducing electrical series resistance and mitigating detrimental optical coupling between waveguides, while ensuring that the semiconductor junction diodes remain reverse-biased.
Implementation Method 1
electro-optic modulators operate by modifying one or more properties of optical waveforms according to information, such as digital data, provided by electrical signals
Data Source
AI summary
An optical modulator includes a Mach-Zehnder interferometer including (i) a first optical waveguide including a first semiconductor junction diode, and (ii) a second optical waveguide including a second semiconductor junction diode. A semiconductor region connects the first and second semiconductor junction diodes such that a distance between the first and second optical waveguides is less than 2.0 μm for at least a portion of a longitudinal direction of the optical modulator. In another aspect, a method of modulating an optical signal includes splitting input light into first and second optical transmission paths; modulating a phase difference between light in the first optical transmission path and light in the second optical transmission path without applying a bias voltage through an impedance less than 100 ohm between the first and second optical transmission paths; and combining light that is output from the first and second optical transmission paths.