Surface Plasmon Optical Modulator for Low Voltage Linearity
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Solution Overview
Problem
Existing ultra-fast light modulation devices face limitations in control voltage, linearity, dynamics, insertion losses, and noise factor, particularly in opto-microwave applications, with existing modulators exhibiting non-linear responses, stability issues, and bandwidth limitations.
Innovation Solution
An optical carrier modulator using surface plasmons with an integrated technology based on semiconductor materials, featuring a guiding structure and a Schottky contact that generates surface plasmon waves, allowing for asymmetric confinement and modulation of the optical wave with low control voltage and high linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If electro-optical niobate modulators are used for amplitude and phase modulation, then integration over a wide band of frequencies is achieved, but the interaction length becomes long and non-linear responses occur
Solution Approach 1:
The patent changes the fundamental modulation mechanism from electro-optical effect to surface plasmon resonance effect. By utilizing the resonant coupling between optical waves and surface plasmons at the metal-semiconductor interface, the modulation occurs over a much shorter interaction length while maintaining wide frequency band integration capability.
Solution Approach 2:
The patent replaces the electro-optical mechanism (which requires long interaction lengths) with a surface plasmon resonance mechanism. The surface plasmon waves are generated at the metal-semiconductor interface and provide strong light-matter interaction over a short distance, eliminating the need for long interaction lengths while achieving wideband modulation.
2Loss of energy
If polymer electro-optical modulators are used with low dielectric constant materials, then losses are reduced and wide frequency band operation is achieved, but material stability and polarization control become problematic
Solution Approach 1:
The patent employs a composite structure combining metal layers and semiconductor layers to generate surface plasmons. This composite material approach replaces the polymer electro-optical materials with a metal-semiconductor system that provides both low losses and high material stability, as metals and semiconductors are inherently more stable than polymers.
Solution Approach 2:
The patent substitutes the polymer-based electro-optical modulation mechanism with surface plasmon resonance in metal-semiconductor structures. This substitution eliminates the polarization and stability issues associated with polymer materials while maintaining low dielectric losses through the metallic and semiconducting components.
3Reliability
If acousto-optic modulators are used for robust amplitude and frequency modulation, then device robustness is improved, but the operating frequency band becomes limited
Solution Approach 1:
The patent changes the modulation mechanism from acousto-optic interaction to surface plasmon resonance. Surface plasmon resonance can be tuned across a wide frequency range by adjusting the metal and semiconductor layer parameters, enabling the device to operate over a broad frequency band while maintaining robustness through the solid-state metal-semiconductor structure.
4Device complexity
If electro-absorption modulators are used for amplitude modulation, then good integration is achieved, but spectral selectivity deteriorates and temperature dependence increases
Solution Approach 1:
The patent changes the modulation mechanism from electro-absorption to surface plasmon resonance. The surface plasmon resonance provides sharp spectral selectivity because the resonance condition is highly sensitive to the optical parameters, allowing precise wavelength selection. The metal-semiconductor structure maintains good integration capability while eliminating temperature dependence through the robust plasmonic mechanism.
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
The modulator achieves reduced bulk and improved transfer function, enabling efficient transmission of analog microwave signals with low insertion losses and high linearity, suitable for wideband applications in telecommunications and defense systems.
Implementation Method 1
a so-called upper metallic layer with Schottky contact intended to receive in particular an optical wave allowing the generation of a surface plasmon wave at the level of the metal/semiconductor interface
Implementation Method 2
The electrical control signal applied at this contact modifies the index of the semiconductor layers disturbing the propagation of the generated plasmon wave
Implementation Method 3
a set of semiconductor layers comprising a guiding structure for an incident optical wave introduced into said guiding structure, said guiding structure providing asymmetric confinement of said optical wave
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
The modulator has an assembly of semiconductor layers forming a multimode guiding structure for an incident optical wave (Oi) introduced into the guiding structure. The guiding structure ensures an asymmetrical confinement of the incident optical wave, and a Schottky contact (26) receives the optical wave allowing the generation of a plasmonic surface wave at the level of a metal/semiconductor interface. An optical index modulating module modulates an optical index at the level of the Schottky contact to create modulation of an optical wave (Om) reflected at the level of the interface.