Capacitor Resonator Modulator Using Polycrystalline Semiconductor
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Solution Overview
Problem
Current capacitor resonator modulators, particularly PN-junction ring resonators, face challenges such as high power consumption, large insertion losses, and complex fabrication processes, including the need for precise ion implantation and reverse bias voltage application to achieve modulation bandwidths greater than 5 GHz.
Innovation Solution
A capacitor resonator modulator is developed using a ring-shaped insulating region sandwiched between outer and inner conductive regions, where at least one of the conductive regions is made of polycrystalline semiconductor material, eliminating the need for intermediate crystallization steps and reducing fabrication complexity and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If PN-junction ring resonators are used to achieve modulation bandwidths greater than 5 GHz, then reverse bias voltage must be applied to widen the depletion region, but this increases device complexity and power consumption
Solution Approach 1:
The patent changes the fundamental operating parameter from PN-junction depletion region control to capacitor-based electric field control. By using a capacitor structure with top and bottom electrodes separated by an insulator layer, the modulation mechanism shifts from requiring reverse bias voltage to simply applying voltage across the capacitor, achieving high bandwidth without complex bias circuits
Solution Approach 2:
The invention extracts and eliminates the complex reverse bias voltage application circuitry from the system. The capacitor-based modulator achieves high-speed modulation through direct voltage application across the capacitor structure, removing the need for assisted bandwidth improvement circuits and complex bias management
2Speed
If PN-junction ring resonators are used to achieve modulation bandwidths greater than 5 GHz, then reverse bias voltage must be applied to widen the depletion region, but this increases power consumption
Solution Approach 1:
The patent changes the fundamental operating parameter from PN-junction depletion region control to capacitor-based electric field control. By using a capacitor structure with top and bottom electrodes separated by an insulator layer, the modulation mechanism shifts from requiring reverse bias voltage to simply applying voltage across the capacitor, achieving high bandwidth without complex bias circuits
Solution Approach 2:
The capacitor-based modulator structure inherently provides low-power operation through its design. The insulator layer with high breakdown field strength allows efficient electric field control without requiring continuous power consumption for bias maintenance, and the structure naturally confines the electric field to the active region
3Manufacturing precision
If precise ion implantation is used to set the junction around optical mode centre region, then modulation efficiency is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the complex reverse bias voltage application circuitry from the system. The capacitor-based modulator achieves high-speed modulation through direct voltage application across the capacitor structure, removing the need for assisted bandwidth improvement circuits and complex bias management
Solution Approach 2:
The patent changes the fundamental operating parameter from PN-junction depletion region control to capacitor-based electric field control. By using a capacitor structure with top and bottom electrodes separated by an insulator layer, the modulation mechanism shifts from requiring reverse bias voltage to simply applying voltage across the capacitor, achieving high bandwidth without complex bias circuits
4Manufacturing precision
If excess doping concentrations are used in core waveguides to increase modulation efficiency, then modulation efficiency is improved, but insertion losses of laser light increase
Solution Approach 1:
The patent changes the fundamental operating parameter from PN-junction depletion region control to capacitor-based electric field control. By using a capacitor structure with top and bottom electrodes separated by an insulator layer, the modulation mechanism shifts from requiring reverse bias voltage to simply applying voltage across the capacitor, achieving high bandwidth without complex bias circuits
Solution Approach 2:
The invention extracts and eliminates the complex reverse bias voltage application circuitry from the system. The capacitor-based modulator achieves high-speed modulation through direct voltage application across the capacitor structure, removing the need for assisted bandwidth improvement circuits and complex bias management
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 use of polycrystalline semiconductor materials allows for efficient light modulation with reduced optical losses and lower production costs, enabling the creation of fully functional resonator modulators without the need for crystallization steps, thus improving modulator efficiency and scalability.
Implementation Method 1
changing an applied bias voltage across a PN-junction modulator changes the width of the depletion region, which in turn changes the refractive index of the waveguide material (e.g. integrated silicon) and subsequently the resonance wavelength through the plasma dispersion effect
Implementation Method 2
free charge carries (e.g. electrons and holes) move from the semiconductor material and towards the insulator layer. However, the free charge carriers cannot pass through the insulator layer embedded in the waveguide centre, so the carrier charges instead accumulate on two semiconductor/insulator interfaces, allowing efficient light modulation by carrier variations
Data Source
AI summary
A resonator modulator for modulating light in a photonic circuit, the modulator comprising: a capacitor formed of a ring-shaped insulating region sandwiched between an outer conductive region and an inner conductive region, wherein at least one of the outer conductive regions or the inner conductive regions is a polycrystalline semiconductor material.