Plasmonic Transducer Head for Sub-Diffraction Optical Storage

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Solution Overview

Problem

Current optical storage technologies, including 3D optical media, are limited by the diffraction limit of laser light, which restricts areal density and storage capacity, as they cannot focus below a certain spot size, limiting the number of layers that can be effectively stored and read.

Innovation Solution

A plasmonic transducer head is introduced, comprising a plasmon antenna and a near-field transducer that converts light pulses into plasmon pulses, allowing for focusing to a smaller spot size than the diffraction limit, enabling higher data density by exciting fluorescent signals in the storage medium, and a fluorescence detector to read these signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If conventional laser light is used for optical storage, then the system is simple and reliable, but the areal density is limited by the diffraction limit

Engineering Contradiction:

Improveareal densityVSAvoiddevice complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent introduces a near-field transducer (NFT) as an intermediary component that converts optical energy to plasmonic energy. This NFT acts as a mediator between the conventional laser source and the storage medium, enabling sub-diffraction focusing through surface plasmon polaritons while maintaining compatibility with existing laser technology

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the fundamental parameter of light focusing from diffraction-limited optical focusing to plasmonic near-field focusing. By utilizing surface plasmon polaritons and near-field effects, the system achieves spatial confinement below the diffraction limit, fundamentally altering the focusing mechanism to overcome the areal density barrier

Inventive Principle:

Principle #35Parameter changes

2Area of moving object

If the spot size is reduced below the diffraction limit, then the areal density increases, but conventional laser light cannot achieve this spot size

Engineering Contradiction:

Improvespot sizeVSAvoidreliability

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

The patent replaces the conventional optical focusing mechanism (governed by diffraction laws) with a plasmonic near-field mechanism. By using surface plasmon polaritons and evanescent fields, the system achieves sub-diffraction spot sizes without relying on traditional optical lens limitations, fundamentally substituting the focusing physics

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Quantity of substance

If the number of storage layers is increased, then the storage capacity increases, but reading and writing becomes more difficult

Engineering Contradiction:

Improvenumber of layersVSAvoiddifficulty of detecting and measuring

Core Design Contradiction:

Quantity of substanceVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies local quality by using near-field plasmonic excitation that is highly localized to the focal region. This localized excitation allows selective addressing of specific storage layers without interfering with adjacent layers, enabling precise read/write operations in multi-layer configurations through spatially confined energy deposition

Inventive Principle:

Principle #3Local quality

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 plasmonic transducer head achieves higher data density by focusing to smaller spot sizes, effectively increasing the number of layers that can be stored and read, overcoming the limitations imposed by the diffraction limit of laser light, thereby enhancing storage capacity.

Implementation Method 1

a near field transducer (NFT) to receive the focused light pulse and convert it to a plasmon pulse directed on a target area to be read from the optical storage medium

Methodology Applied

Scientific EffectPlasmon resonance: Surface Acoustic Wave

Implementation Method 2

The plasmon pulse excites the target area to emit a fluorescent signal

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Implementation Method 3

a plasmon antenna including a light source to generate a light pulse, a plasmon antenna optics set to receive and focus the light pulse

Methodology Applied

Scientific EffectLight focusing: Focusing

Implementation Method 4

a fluorescence detector configured to detect fluorescence of the target area caused by the plasmon pulse

Methodology Applied

Scientific EffectFluorescence detection: Fluorescence

Data Source

PatentUS11335373B1Plasmonic transducer head for writing data to and reading data from an optical recording medium ultilizing a fluorescent dye

Publication Date: 2022.05.17 SEAGATE TECH LLC

AI summary

3D optical data storage refers to forms of optical data storage in which information can be recorded and/or read with 3D resolution. 3D optical media are generally limited in areal density by the diffraction limit of laser light used to read and/or write data to and/or from the optical media. It is thus advantageous to find ways to store data on 3D optical media with a spot size below the diffraction limit of an associated laser reader to further increase areal density of the optical media. A hybrid approach that utilizes plasmon technology to access a surface layer of the 3D optical media with an extremely small spot size and photon technology to access interior layers of the 3D optical media with a larger spot size may substantially increase overall data density of the 3D optical media.