Floating-Gate Optical Waveguide for Nonvolatile Photonic Memory
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Solution Overview
Problem
Conventional photonic circuits are incapable of implementing nonvolatile memory, limiting their ability to store data persistently and efficiently.
Innovation Solution
Incorporating an optical waveguide as a floating gate that is electrically isolated by an insulator layer, allowing charge to be retained nonvolatively through quantum tunneling, and leveraging this property to modulate the refractive index and function as both electrical and optical nonvolatile memory or a programmable optical switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional photonic circuits are used, then optical signal transmission is achieved, but nonvolatile memory capability is lost
Solution Approach 1:
The patent merges the optical waveguide function with the floating gate memory function into a single integrated structure. The optical waveguide serves dual purposes: transmitting optical signals and storing electrical charge as a floating gate, thereby combining photonic circuit functionality with nonvolatile memory capability in one component.
Solution Approach 2:
The optical waveguide is designed to perform multiple functions simultaneously: it acts as both an optical transmission medium and an electrical charge storage element (floating gate). This multi-functionality enables the photonic circuit to inherently provide nonvolatile memory capability without adding separate memory components.
2Duration of action of stationary object
If quantum tunneling is used to charge the floating gate, then nonvolatile charge storage is achieved, but device complexity increases
Solution Approach 1:
The patent utilizes quantum tunneling effects by precisely controlling the thickness and material properties of the insulator layer. By adjusting the insulator layer parameters (thickness, composition) to specific ranges, the device enables charge storage through quantum tunneling while managing the complexity through parameter optimization rather than structural complexity.
3Reliability
If the floating gate is electrically isolated by insulator layers, then charge is retained nonvolatively, but manufacturing precision requirements increase
Solution Approach 1:
The patent achieves reliable charge retention by optimizing the insulator layer thickness to a specific range that enables quantum tunneling while remaining manufacturable. This parameter optimization balances the need for effective electrical isolation and charge retention with the practical constraints of manufacturing precision.
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
Enables the creation of nonvolatile memory cells and optical switches within photonic circuits that consume minimal power, maintaining their state without continuous electrical power, suitable for low-power applications and advanced computing tasks.
Implementation Method 1
the floating gate can be charged or discharged through the insulator layer via quantum tunneling (e.g., Fowler-Nordheim tunneling, hot carrier injection, direct bandgap tunnelling, or thermionic emission)
Implementation Method 2
presence or absence of electrical charge in an optical waveguide influences an index of refraction of that optical waveguide. As a result of this electro-optic effect, the refractive index of the optical waveguide/floating gate is different between a charged state or an uncharged state of the floating gate
Data Source
AI summary
A semiconductor device includes a floating gate that can be charged in a nonvolatile manner. The floating gate is also structured as an optical waveguide, and may be optically coupled to a photonic circuit, such as an interferometer.