Hybrid MOSCAP Phase Tuning With Integrated Silicon Waveguide Elements
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Solution Overview
Problem
Conventional silicon-based optical modulators exhibit weak and inefficient phase shift due to carrier accumulation or depletion, limiting their modulation efficiency in optical transmitters.
Innovation Solution
A hybrid metal-oxide-semiconductor (MOS) ring-resonator optical modulator with a thin interfacial oxide layer between dissimilar semiconductors, integrated with a resistor element, PIN junction diode, or PN junction diode, enhances phase shift efficiency by modifying the refractive index of the optical waveguide through charge accumulation and depletion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional silicon-based optical modulators use carrier accumulation or depletion for phase shift, then the device structure is simple, but the phase shift efficiency is weak and inefficient
Solution Approach 1:
The patent employs a hybrid metal-oxide-semiconductor structure combining silicon waveguide with aluminum oxide dielectric layer and metal electrode. This composite material system enables strong plasma dispersion effect and efficient charge accumulation, achieving enhanced phase shift efficiency while maintaining manufacturability through standard CMOS-compatible fabrication processes
Solution Approach 2:
The patent modifies key parameters including using thin aluminum oxide dielectric layer (5-20 nm), optimizing metal electrode configuration, and controlling charge carrier density in the semiconductor layer. These parameter changes enable strong phase shift effect by enhancing the plasma dispersion effect and improving charge accumulation efficiency at the metal-oxide-semiconductor interface
2Speed
If conventional optical modulators are used for high speed modulation, then the modulation bandwidth is limited, but increasing the device complexity can improve performance
Solution Approach 1:
The patent replaces traditional mechanical or complex electro-optic modulation mechanisms with a field-effect based modulation approach. By applying voltage to the metal electrode, electric field induces charge accumulation in the semiconductor layer, achieving high-speed phase modulation without moving parts or complex structures, enabling modulation speeds beyond 100 GHz
Solution Approach 2:
The patent implements dynamically controllable phase shift through voltage-tunable charge carrier density in the semiconductor layer. The modulation depth and bandwidth can be dynamically adjusted by changing the applied voltage, enabling adaptive optimization for different modulation speeds and formats without hardware changes
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 enhanced phase shift properties improve modulation efficiency, enabling wider wavelength shifts and higher speed modulation, suitable for Dense Wavelength Division Multiplexing (DWDM) systems and micro-ring lasers.
Implementation Method 1
A signal applied across the capacitor induces an accumulation of charge near the center of the capacitor. This accumulation of charge modifies a refractive index of the optical waveguide as well as its propagation loss. Modifying the refractive index causes a phase shift in a beam of light propagating through the waveguide
Data Source
AI summary
Implementations disclosed herein provide for improving phase tuning efficiency of optical devices, such as a hybrid metal-on-semiconductor capacitor (MOSCAP) III-V/Si micro-ring laser. The present disclosure integrates silicon devices into a waveguide structural of the optical devices disclosed herein, for example, a waveguide resistor heater, a waveguide PIN diode, and waveguide PN diode. In some examples, the optical devices is a MOSCAP formed by a dielectric layer between two semiconductor layers, which provides for small phase tuning via plasma dispersion and/or carrier dispersion effect will occur depending on bias polarity. The plasma dispersion and/or carrier dispersion effect is enhanced according to implementations disclosed herein by heat, carrier injection, and/or additional plasma dispersion based on the silicon devices disclosed integrated into the waveguide.