Optical Comb Encoder for High-Speed CAM Search Without O-E Conversion

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Solution Overview

Problem

Existing electrical Content-Addressable Memories (CAMs) and Ternary CAMs (TCAMs) consume large amounts of power and are inefficient, leading to bottlenecks in high-speed communication systems, as they require costly optical-to-electrical conversions to search encoded optical signals, reducing network efficiency and throughput.

Innovation Solution

An optical encoder using a multi-wavelength comb source and tunable wavelength filters, such as microring resonators, encodes search words in the spectral domain, allowing for low-energy, high-speed searches in optical TCAMs by modifying the spectrum of multi-wavelength optical signals to represent bit values and wildcard criteria, thereby eliminating the need for electrical conversions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If optical-to-electrical conversions are used to search encoded optical signals in existing CAMs and TCAMs, then the search function can be performed, but power consumption increases and processing speed decreases

Engineering Contradiction:

Improvesearch speedVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the electrical search mechanism with an optical search mechanism. Instead of converting optical signals to electrical signals for processing and then back to optical, the system performs search operations entirely in the optical domain using photonic components such as microring resonators and optical encoders, eliminating the need for optical-to-electrical conversions and reducing both power consumption and processing delays

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transitions from electrical domain processing to optical domain processing by encoding search words in the spectral domain of optical signals. Different bit values are represented by different wavelength combinations, enabling parallel optical processing that simultaneously evaluates multiple search criteria without the sequential constraints of electrical processing

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Productivity

If optical-to-electrical conversions are implemented for searching optical signals, then data can be processed, but network efficiency and throughput are reduced

Engineering Contradiction:

Improvenetwork throughputVSAvoidconversion complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent eliminates optical-to-electrical conversion stages by implementing the entire search functionality in the optical domain. Photonic components directly process optical signals containing encoded data and search criteria, removing conversion complexity and enabling higher network throughput by keeping signals in the optical domain throughout the search process

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 optical encoder significantly speeds up search processes in optical TCAMs by encoding search words in the spectral domain, reducing power consumption and increasing efficiency, enabling parallel searches across a large array of bits with minimal latency.

Implementation Method 1

an optical comb source to generate a multi-wavelength optical comb

Methodology Applied

Scientific EffectOptical comb generation: Laser

Implementation Method 2

a number of optical filters sequentially coupled to the optical comb source, with a respective optical filter being tunable to pass or block a particular wavelength

Methodology Applied

Scientific EffectOptical filtering: Filter (optical)

Implementation Method 3

respective optical filter being tunable to pass or block a particular wavelength

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS11469764B2Optical comb source for content-addressable memory encoders

Publication Date: 2022.10.11 HEWLETT PACKARD ENTERPRISE DEV LP

AI summary

One embodiment provides an optical encoder. The optical encoder includes an optical comb source to generate a multi-wavelength optical signal; a number of optical filters sequentially coupled to the optical comb source, with a respective optical filter being tunable to pass or block a particular wavelength of the multi-wavelength optical signal based on a corresponding bit value of a multi-bit search word; and a common output for the optical filters to output the filtered multi-wavelength optical signal, which encodes the multi-bit search word and can be used as an optical search signal for searching an optical content-addressable memory (CAM).