Multistate Photonic Memory With Low-Loss Phase-Change Materials
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Solution Overview
Problem
Existing photonic memory technologies face high insertion losses, high switching energy, and limited cycle durability, which restrict the number of neurons and updates in photonic networks, and lack efficient strategies for storing more information.
Innovation Solution
A low loss multistate photonic memory device using stoichiometrically engineered phase change materials (Ge2Sb4Se4Te1 or Ge2Sb2Se5) with electro-thermal interaction for data storage and photon-based reading, eliminating the need for DAC and phase tuners.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional phase change materials (GST) are used for photonic memory, then data storage capability is achieved, but insertion losses are high
Solution Approach 1:
The patent changes the material composition parameters by using stoichiometrically engineered phase change materials (Ge2Sb4Se4Te1 or Ge2Sb2Se5) instead of conventional GST, which fundamentally alters the optical properties to achieve lower insertion losses while maintaining data retention capability
Solution Approach 2:
The patent employs composite phase change materials with specific multi-element compositions (Ge-Sb-Se-Te) that combine the beneficial properties of different elements to reduce optical losses while preserving the phase change functionality needed for reliable data storage
2Use of energy by moving object
If conventional photonic memory devices are used, then data storage is achieved, but switching energy is high
Solution Approach 1:
The patent modifies the material composition parameters of the phase change material to achieve lower melting and phase transition temperatures, which directly reduces the switching energy required while enabling faster update cycles and higher productivity
3Duration of action of stationary object
If conventional photonic memory is used, then basic storage function is provided, but number of cycles is limited
Solution Approach 1:
The patent changes the material parameters by incorporating specific elements (Se and Te) in controlled stoichiometric ratios, which enhances the structural stability and fatigue resistance of the phase change material, enabling it to withstand a higher number of write/erase cycles and supporting deeper neural network operations
4Area of stationary object
If conventional photonic memory architecture is used, then storage is achieved, but surface area efficiency is poor
Solution Approach 1:
The patent extracts and eliminates unnecessary components (DAC and phase tuners) from the photonic memory architecture, simplifying the device structure and improving surface area utilization by removing elements that do not directly contribute to the core storage function
Solution Approach 2:
The patent designs the photonic memory device to perform multiple functions (storage, reading, and potential computing operations) using the same physical structure, eliminating the need for separate dedicated components and thereby improving surface area efficiency
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 device achieves reduced loss and enhanced durability, allowing for efficient multistate data storage and computation near the memory, overcoming limitations of previous technologies.
Implementation Method 1
When heated with an intense pulse of laser light or electrothermally, GST film changes its atomic structure between an ordered crystalline lattice and an 'amorphous' state
Implementation Method 2
These two structures reflect and absorb light in different ways
Implementation Method 3
uses an electro-thermal interaction or an enhanced light matter interaction for storing data
Data Source
AI summary
Multistate non-volatile photonic memory devices are disclosed. The photonic devices comprise phase change materials with broadband transparencies used to store discretized information with negligible losses in the 0 state. The photonic memories comprise multiple configurations for reading and writing multi-bit words. The reading mechanisms comprises schemes based on light-absorption (FIG. 1), shift in resonances of a cavity (ring resonator, photonic crystal; FIG. 2) or interferometric schemes (FIG. 3). The photonic memory devices employ multiple techniques for writing electrically (FIG. 4 and related performance) and/or all-optically (FIGS. 7-10). The optical writing can be performed with pulsed laser light coming either from free space or on-chip using dedicated writing lines and opportune drops.