Draft proposal for concepts for opto memristor and proposed microscope design for testing the said optical memristor materials.
The follow up to this is here:
http://www.slideshare.net/faissal.bd/nonthermal-optomagnetic-memristors-and-characterization-by-ultrafast-pump-and-probe-polarimetric-microscopy/v1
A solar cell (photovoltaic devices) is a pn junction device with no voltage directly applied across the junction (used with zero bias).
A photodiode is a pn junction diode operated with an applied reverse-biased voltage.
A solar cell (photovoltaic devices) is a pn junction device with no voltage directly applied across the junction (used with zero bias).
A photodiode is a pn junction diode operated with an applied reverse-biased voltage.
Introduction of all kinds of organic materials and their applications. More information about organic materials is on Alfa Chemistry.
http://www.alfa-chemistry.com/products/optoelectronic-materials-132.htm
Solar PV Power Plant on Water Floating Structure,Ground Latest Information Presentation by JMV LPS MNRE/SECI/NSM/NHPC/NTPC/REC Power Distribution/CEA,Solar EPC Companes,Electrical Contractor ,Solar Consultant ,Solar Power Developers
An introduction to solar PV basics, starting from solar cells to PV arrays, giving an overview of on grid and off grid PV system. The presentation also introduce the three PV cells technology which are most in use.
Nonthermal Opto-Magnetic Memristors and Characterization by Ultrafast Pump an...M. Faisal Halim
Proposal for concepts for opto memristor and proposed microscopy techniques for testing the said optical memristor materials.
Apparently, Slideshare cannot have the page numbers (from MS Word documents) starting from zero, and it cannot display Word's automatically generated table of contents. So, the table of contents shown here is a graphic with the numbers displaced by one -- if the page number is said to be '1' then the material is on a page which is numbered as '2.' Sorry for the inconvenience, but this is a little out of my hands.
This is a follow up to:
http://www.slideshare.net/faissal.bd/draft-proposal-for-concepts-for-opto-memristor-and-proposed-microscope-design-for-testing-the-said-optical-memristor-materials
Active vibration control of smart piezo cantilever beam using pid controllereSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Introduction of all kinds of organic materials and their applications. More information about organic materials is on Alfa Chemistry.
http://www.alfa-chemistry.com/products/optoelectronic-materials-132.htm
Solar PV Power Plant on Water Floating Structure,Ground Latest Information Presentation by JMV LPS MNRE/SECI/NSM/NHPC/NTPC/REC Power Distribution/CEA,Solar EPC Companes,Electrical Contractor ,Solar Consultant ,Solar Power Developers
An introduction to solar PV basics, starting from solar cells to PV arrays, giving an overview of on grid and off grid PV system. The presentation also introduce the three PV cells technology which are most in use.
Nonthermal Opto-Magnetic Memristors and Characterization by Ultrafast Pump an...M. Faisal Halim
Proposal for concepts for opto memristor and proposed microscopy techniques for testing the said optical memristor materials.
Apparently, Slideshare cannot have the page numbers (from MS Word documents) starting from zero, and it cannot display Word's automatically generated table of contents. So, the table of contents shown here is a graphic with the numbers displaced by one -- if the page number is said to be '1' then the material is on a page which is numbered as '2.' Sorry for the inconvenience, but this is a little out of my hands.
This is a follow up to:
http://www.slideshare.net/faissal.bd/draft-proposal-for-concepts-for-opto-memristor-and-proposed-microscope-design-for-testing-the-said-optical-memristor-materials
Active vibration control of smart piezo cantilever beam using pid controllereSAT Publishing House
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Active vibration control of smart piezo cantilever beam using pid controllereSAT Journals
Abstract In this paper the modelling and Design of a Beam on which two Piezoelectric Ceramic Lead Zirconate Titanate ( PZT) patches are bonded on the top and bottom surface as Sensor/Actuator collocated pair is presented. The work considers the Active Vibration Control (AVC) using Proportional Integral Derivative (PID) Controller. The beam is assumed as Euler-Bernoulli beam. The two PZT patches are also treated as Euler-Bernoulli beam elements. The contribution of mass and stiffness of two PZT patches in the design of entire structure are also considered. The beam is modelled using three Finite Elements. The patches can be bonded near the fixed end, at middle or near the free end of the beam as collocated pair. The design uses first two dominant vibratory modes. The effect of PZT sensor/actuator pair is investigated at different locations of beam in vibration control. It can be concluded from the work that best result is obtained when the PZT patches are bonded near the fixed end. Keywords: Smart Beam, Active Vibration control, Piezoelectric, PID Controller, Finite Element
SMART MATERIALS AND MEMS_17ME745_Full note.docxRoopaDNDandally
JSS ACADEMY OF TECHNICAL EDUCATION
JSS campus, Dr. Vishnuvaradhan road, Bangalore -60
DEPARTMENT OF MECHANICAL ENGINEERING
Sub: Smart Materials and MEMS
Question bank - Module – I
Text Book: “Smart structures – Analysis and Design” by A V Srinivasan. Cambridge University Press 2001.
1. What are smart materials? Explain its application in various fields.
2. Explain the active and passive smart materials and also open loop and closed loop smart structure.
3. List the applications of smart structures and explain.
4. What are piezoelectric materials? Explain their properties
5. Explain the use of piezoelectric material in a Inchworm Linear motor.
6. Derive an equation for actuation of structural components by piezoelectric crystal under axial motion of rods considering various loading.
7. What are shape memory alloys? Applications of shape memory alloys.
8. Explain with neat sketches, one way and two wayshape memory effect.
9. Develop a mathematical model to find martensitic fraction in an SMA at critical temperatures by considering only the effect of temperature. (Explain experimental phenomenology of SMA)
10. Explain the effect of stress on the characteristic temperature by deriving an expression for upper and lower limits of stress for phase transformation. (super elasticity)
11. With a neat sketch explain stress-strain characteristics of SMA as a function of temperature.
12. Discuss the advantages of multiplexing embedded NiTiNOL actuators.
13. Explain with neat sketch vibration control using a NiTiNOL wire supporting a weight at the end of a cantilever beam.
14. Explain with neat sketch vibration control of a beam by SMA generated axial force.
15. Explain with neat sketch feasibility of controlling vibration in a beam structure.
JSS ACADEMY OF TECHNICAL EDUCATION
JSS campus, Dr. Vishnuvaradhan road, Bangalore -60
DEPARTMENT OF MECHANICAL ENGINEERING
Sub: Smart Materials and MEMS
Question bank - Module – 2
Ref: Smart structures - Analysis and design by A V Srinivasan
1. Discuss fluid composition and behavior of ER and MR fluids
2. What are MR Dampers? Explain the characteristics of controllable fluid dampers as applied to civil structures.
3. Explain the application of MR fluids in the clutches used to transfer torque between rotating mechanical components
4. Explain the Bingham plastic material model of ER and MR fluids.
5. Discuss application of ER and MR fluids in clutches and dampers
6. Differentiate between the properties of ER and MR fluids.
7. Explain the principle of working of MR fluids with a sketch
8. What are ER fluids? Discuss their merits and demerits. With a sketch explain working of MR damper.
9. Explain the concept of “Total Internal Refection”. How it is useful in fiber optics? Derive Numerical Aperture of optical fiber.
10. Explain how embedded fiber optic sensors can be used as chemical sensors in structures.
11. Explain the fiber optic principle. Discuss on technique of measuring strain using
Resonance frequency analysis of laser optical fiber based on microcantileverIJECEIAES
The normal frequency of smart beams was originated utilizing FEM [Ansys and Comsol] code for first five modes by varying the position of actuator from the fixed end of the structure, and it has a suitable arrangement with analytically found the standard frequency. This paper includes learning a resonance frequency analysis of laser optical fiber based on microcantilever of designing magnetic actuator using Ansys and Comsol simulation. The design of optical fiber includes Nickel cantilever, two magnets and one coil that apply to force on the cantilever. After the current flows in the coil domain, the shape of microcantilever will be deformed. It will move to z- direction that depends on the force direction. Two methods including, Comsol Multiphysics, Ansys and analytical equations have been utilized to calculate the resonance frequency, current and force values. The simulation results include calculating the current (magnetic current density) and effects of the magnetic field of the coil on the cantilever (force calculation). Utilizing this method is to limit faults(errors) of optical fiber laser between transmitter and receiver system (detection system) for any time of cutting coil when the signal of a laser passes through the coil. In conculsions, resonant frequency (f_n) tuning using cantilivier presented in the resrach have larger variable range by using simulations. However,the adjusting of the system and changing the deminsions.Resolutions to this problematic contain tuning the modes of resonant frequency to produce by cantilivier with 2-magnets and coil when the signal pass from laser source. Based on these simulations and characterization results, the proposed assembly can be a good applicant for evolving a low price, high material platform for many biological, laser optical fiber, communication, machine learning, biosensors and biomedical applications.
THERMOGRAPHY AND EDDY CURRENT TESTING (ET)laxtwinsme
Thermography- Principles, Contact and non contact inspection methods, Techniques for applying liquid crystals, Advantages and limitation - infrared radiation and infrared detectors, Instrumentations and methods, applications. Eddy Current Testing-Generation of eddy currents, Properties of eddy currents, Eddy current sensing elements, Probes, Instrumentation, Types of arrangement, Applications, advantages, Limitations, Interpretation/Evaluation
Magneto Optic Current Transformer Technology (MOCT)IOSRJEEE
An accurate electric current transducer is a key component of any power system instrumentation. To measure currents power stations and substations conventionally employ inductive type current transformers .For high voltage applications, porcelain insulators and oil-impregnated materials have to be used to produce insulation between the primary bus and the secondary windings. The insulation structure has to be designed carefully to avoid electric field stresses, which could eventually cause insulation breakdown. The electric current path of the primary bus has to be designed properly to minimize the mechanical forces on the primary conductors for through faults. The reliability of conventional high-voltage current transformers have been questioned because of their violent destructive failures which caused fires and impact damage to adjacent apparatus in the switchyards, electric damage to relays, and power service disruptions. In addition to the concerns, with the computer control techniques and digital protection devices being introduced into power systems, the conventional current transformers have caused further difficulties, as they introduce electromagnetic interference through the ground loop into the digital systems. Magneto-optical current transformer(MOCT)technology provides a solution for many of the above mentioned problems. The MOCT measures the electric current by means of Faraday Effect that is the orientation of polarized light rotates under the influence of the magnetic fields and the rotation angle is proportional to the strength of the magnetic field component in the direction of optical path. MOCT is a passive optical current transducer which uses light to accurately measure current on high voltage systems and determines the rotation angle & converts it into a signal of few volts proportional to the current
In this presentation, basics of solar cells, what is piezoelectricity and its application, followed by basics of thermoelectricity and its application would be discussed.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Design and development of a linear variable differential optical sensor for s...eSAT Journals
Abstract In this present paper, we have illustrated the development of a novel linear displacement sensor utilizing the intensity of light. This sensor is based on temporal changes in the intensity of diffuse light beam for the movement of a solid metallic obstacle between the source and detector instead of traditional reflector. An obstacle is moved over open surface of a hollow shaped channel, where light beams impinged vertically into the channel. Two photo detectors has been used to sense the variation of diffuse light intensity at the covered & uncovered area of channel surface due to the movement of obstacle over its open surface. This movement of an obstacle represents the actual target displacement by differentiating the output transformation of two photo detectors; this phenomenon is reported as linear variable differential optical sensor (LVDOS). The measured displacement recorded interns of voltage by the signal processing circuit (SPC). Experimental results are shown a satisfactory performance of the sensor for small range displacement measurement. Index terms: Linear Variable Displacement Sensor, Intensity of diffuse light beam, solid metallic obstacle, Photo detector
In our conventional electronic devices we use semi conducting materials for logical operation and magnetic materials for storage, but spintronics uses magnetic materials for both purposes. These spintronic devices are more versatile and faster than the present one. One such device is Spin Valve Transistors (SVT).
Spin valve transistor is different from conventional transistor. In this for conduction we use spin polarization of electrons. Only electrons with correct spin polarization can travel successfully through the device. These transistors are used in data storage, signal processing, automation and robotics with less power consumption and results in less heat. This also finds its application in Quantum computing, in which we use Qubits instead of bits.
Solar eclipse 2017 - aaa -- ny sci -- the diamondM. Faisal Halim
This was a primer for the August 2017 Solar Eclipse, given by me to the New York Hall of Science, on behalf of the Amateur Astronomers Association of New York
All optical image processing using third harmonic generation for image correl...M. Faisal Halim
Term Paper: All optical image processing using third harmonic generation for image correlation
Optical Information Processing Course
Monday, 20th December, 2010
Spaser Amplifier for Small Signal Detection for Raman Scattering Measurements...M. Faisal Halim
Originally part of a presentation:
Detection of a single BSA molecule by amplifying its Raman signal.
Done with my friend: Pemba Lama
[I came up with the idea for amplifier (and detector scheme) so that is what I have posted]
For Course Project: Nano and Micro Photonics
Under Prof. Vinod Menon, Queens College and Graduate Center, CUNY
The project was devised so that students come up with original ideas, based on known physical principles, for the detection of a single molecule of BSA (a biological molecule). Unfortunately, this means we could not verify the validity of the work, and my work is no exception. It is my hope that I have not overlooked any relevant physical principles, and that this kind of amplifier is possible. If anyone finds my design promising then:
-I would certainly like to know the simulation and experimental results
-I would like credit in the resulting publication – Thanks.
The substrate work that I did prior to this (and the mis-conceived SPASER work that I previously came up with) is here:
http://www.slideshare.net/faissal.bd/spaser-amplifierforsmallsignaldetectionforramanscatteringmeasurementsofasinglemoleculeofbsa
The SPASER work there is fundamentally flawed, but perhaps the substrate work is not entirely useless.
My 9th Grade Brother asked me what I do in my lab, so I threw together this presentation. I am not sure how much a 9th Grader knows, but I intended this presentation to give him exposure, rather than to have him understand everything. Please feel free to critique my presentation, and certainly point out any pictures that I may have failed to give the original sources credit for.
Analysis Of Carbon Nanotubes And Quantum Dots In A Photovoltaic Device Slide ...M. Faisal Halim
Francis' presentation to Louis Stokes Association for Minority Participation. Since I co-authored this work I think I have the right to a copy. I was the graduate student Francis was working with.
Analysis Of Carbon Nanotubes And Quantum Dots In A Photovoltaic DeviceM. Faisal Halim
Analysis of Carbon Nanotubes and Quantum Dots in a Photovoltaic Device
A poster prepared by Francis and me; presented by Francis. I modified on of the photographs used, in this copy.
Earth Viewing Systems Satellite Sensor Project, for Professor DiNardo's Course.
The presentation was given on 14th May, 2009.
______________________________________
I realize that some of the graphics do not have their sources cited, but I did not make those slides, and the group members who made them did not remember their sources. So, please forgive this oversight, since I consider it important enough to students of the earth surveillance class at The City College of New York (and elsewhere) that old presentations be available to them.
If, however, you can give me the sources of the graphics that you see, then I will be grateful, and I will be happy to cite them.
Climate Impact of Software Testing at Nordic Testing DaysKari Kakkonen
My slides at Nordic Testing Days 6.6.2024
Climate impact / sustainability of software testing discussed on the talk. ICT and testing must carry their part of global responsibility to help with the climat warming. We can minimize the carbon footprint but we can also have a carbon handprint, a positive impact on the climate. Quality characteristics can be added with sustainability, and then measured continuously. Test environments can be used less, and in smaller scale and on demand. Test techniques can be used in optimizing or minimizing number of tests. Test automation can be used to speed up testing.
Generative AI Deep Dive: Advancing from Proof of Concept to ProductionAggregage
Join Maher Hanafi, VP of Engineering at Betterworks, in this new session where he'll share a practical framework to transform Gen AI prototypes into impactful products! He'll delve into the complexities of data collection and management, model selection and optimization, and ensuring security, scalability, and responsible use.
Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
At WSTS 2024, Alon Stern explored the topic of parametric holdover and explained how recent research findings can be implemented in real-world PNT networks to achieve 100 nanoseconds of accuracy for up to 100 days.
State of ICS and IoT Cyber Threat Landscape Report 2024 previewPrayukth K V
The IoT and OT threat landscape report has been prepared by the Threat Research Team at Sectrio using data from Sectrio, cyber threat intelligence farming facilities spread across over 85 cities around the world. In addition, Sectrio also runs AI-based advanced threat and payload engagement facilities that serve as sinks to attract and engage sophisticated threat actors, and newer malware including new variants and latent threats that are at an earlier stage of development.
The latest edition of the OT/ICS and IoT security Threat Landscape Report 2024 also covers:
State of global ICS asset and network exposure
Sectoral targets and attacks as well as the cost of ransom
Global APT activity, AI usage, actor and tactic profiles, and implications
Rise in volumes of AI-powered cyberattacks
Major cyber events in 2024
Malware and malicious payload trends
Cyberattack types and targets
Vulnerability exploit attempts on CVEs
Attacks on counties – USA
Expansion of bot farms – how, where, and why
In-depth analysis of the cyber threat landscape across North America, South America, Europe, APAC, and the Middle East
Why are attacks on smart factories rising?
Cyber risk predictions
Axis of attacks – Europe
Systemic attacks in the Middle East
Download the full report from here:
https://sectrio.com/resources/ot-threat-landscape-reports/sectrio-releases-ot-ics-and-iot-security-threat-landscape-report-2024/
Alt. GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using ...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
The Art of the Pitch: WordPress Relationships and SalesLaura Byrne
Clients don’t know what they don’t know. What web solutions are right for them? How does WordPress come into the picture? How do you make sure you understand scope and timeline? What do you do if sometime changes?
All these questions and more will be explored as we talk about matching clients’ needs with what your agency offers without pulling teeth or pulling your hair out. Practical tips, and strategies for successful relationship building that leads to closing the deal.
UiPath Test Automation using UiPath Test Suite series, part 4DianaGray10
Welcome to UiPath Test Automation using UiPath Test Suite series part 4. In this session, we will cover Test Manager overview along with SAP heatmap.
The UiPath Test Manager overview with SAP heatmap webinar offers a concise yet comprehensive exploration of the role of a Test Manager within SAP environments, coupled with the utilization of heatmaps for effective testing strategies.
Participants will gain insights into the responsibilities, challenges, and best practices associated with test management in SAP projects. Additionally, the webinar delves into the significance of heatmaps as a visual aid for identifying testing priorities, areas of risk, and resource allocation within SAP landscapes. Through this session, attendees can expect to enhance their understanding of test management principles while learning practical approaches to optimize testing processes in SAP environments using heatmap visualization techniques
What will you get from this session?
1. Insights into SAP testing best practices
2. Heatmap utilization for testing
3. Optimization of testing processes
4. Demo
Topics covered:
Execution from the test manager
Orchestrator execution result
Defect reporting
SAP heatmap example with demo
Speaker:
Deepak Rai, Automation Practice Lead, Boundaryless Group and UiPath MVP
Securing your Kubernetes cluster_ a step-by-step guide to success !KatiaHIMEUR1
Today, after several years of existence, an extremely active community and an ultra-dynamic ecosystem, Kubernetes has established itself as the de facto standard in container orchestration. Thanks to a wide range of managed services, it has never been so easy to set up a ready-to-use Kubernetes cluster.
However, this ease of use means that the subject of security in Kubernetes is often left for later, or even neglected. This exposes companies to significant risks.
In this talk, I'll show you step-by-step how to secure your Kubernetes cluster for greater peace of mind and reliability.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...James Anderson
Effective Application Security in Software Delivery lifecycle using Deployment Firewall and DBOM
The modern software delivery process (or the CI/CD process) includes many tools, distributed teams, open-source code, and cloud platforms. Constant focus on speed to release software to market, along with the traditional slow and manual security checks has caused gaps in continuous security as an important piece in the software supply chain. Today organizations feel more susceptible to external and internal cyber threats due to the vast attack surface in their applications supply chain and the lack of end-to-end governance and risk management.
The software team must secure its software delivery process to avoid vulnerability and security breaches. This needs to be achieved with existing tool chains and without extensive rework of the delivery processes. This talk will present strategies and techniques for providing visibility into the true risk of the existing vulnerabilities, preventing the introduction of security issues in the software, resolving vulnerabilities in production environments quickly, and capturing the deployment bill of materials (DBOM).
Speakers:
Bob Boule
Robert Boule is a technology enthusiast with PASSION for technology and making things work along with a knack for helping others understand how things work. He comes with around 20 years of solution engineering experience in application security, software continuous delivery, and SaaS platforms. He is known for his dynamic presentations in CI/CD and application security integrated in software delivery lifecycle.
Gopinath Rebala
Gopinath Rebala is the CTO of OpsMx, where he has overall responsibility for the machine learning and data processing architectures for Secure Software Delivery. Gopi also has a strong connection with our customers, leading design and architecture for strategic implementations. Gopi is a frequent speaker and well-known leader in continuous delivery and integrating security into software delivery.
GDG Cloud Southlake #33: Boule & Rebala: Effective AppSec in SDLC using Deplo...
Draft proposal for concepts for opto memristor and proposed microscope design for testing the said optical memristor materials
1. Proposal:
Microscope Design for Ultrafast Pump and Probe Polarimetric
Characterization of Proposed Novel Materials and Structures Intended
For Use As Optical Memristors Working In Nonthermal Opto-Magnetic
Regime
Faisal Halim, City College of New York (CUNY)
Posted: Monday, 31st May, 2010
Course Professor: Gilchrist, Chemical Engineering, City College of New York (CUNY)
NOTE: This is a draft – I have not yet completed the microscopy aspect of the project,
and I may have to make a few refinements to the optomemristor concept. The
optomemristor concept is my own, and relies on prior work from [5,6,7].
As I have no way to test my ideas they remain what I would describe as “crazy ideas,”
but if anyone find my work useful, then I would appreciate being cited. Thanks.
Abstract: In order to realize an optical memristor the Inverse-Faraday Effect has
been investigated (through literature search) as a means for dynamically altering the
magnetization vector of materials, thus altering their Magneto-Optic Kerr Rotation
response and their Faraday Effect response faster than any other measurable change in
response that can be engineered and measured, and microscopy methods have been
investigated (through literature search) that can be used to characterize these responses
from microscopic samples (since practical devices made from these materials will need to
2. have microscopic components) at the speeds at which the optical memristor devices are
intended to operate.
Aim: The purpose of this project was to devise methods to make an optical memristor,
which will be an optical equivalent of HP’s electrical memristor [1], originally proposed
by Leon Chua [2], and to devise methods to characterize the materials and devices, once
they have been fabricated, in the microscopic size and ultrafast time regimes in which
they are intended to be used.
Introduction: Light propagates faster than electrons and holes and so the optical
responses of materials occur at much shorter time scales than they occur for electrical
responses. As a result there has been a push in the industry, for many years, to make
optical equivalents of electrical devices. Out of the four fundamental passive electrical
components possible [2] the memristor is one that brings neural networking closer to
reality, thus enabling a whole host of applications, like simulating the complexity of a
small animal’s brain, as was done by Jo, et al. [3]. At this junction lies the optical
memristor: a (possible) enabling technology that will also have a speed advantage from
being all-optical.
For a device to be all optical, and thus have all the advantages of using light in place of
electrons or holes, the signals that it receives have to be optical, the signals that it sends
have to be optical, and the processing (which may be enhancement, attenuation, or
change of polarization of the incoming light, or the addition or subtraction of two or more
3. signals, etc.) has to occur due to the interaction of the electric or magnetic field of the
light wave(s) with the material that the device is made of. The result of the interaction
may be steered (or influenced) by the presence of a constant field (electric or magnetic)
that does not need to be manipulated by non-optical means (which would negate the
speed advantages of a fully optical device).
To realize a practical all-optical memristor, or optical memristor, one would need a
device such that:
• Exhibits the following behavior:
o It should be possible to modify one aspect of its optical response quickly and
dynamically (i.e., the same material/device will have one of its optical
properties changed as and when needed, under optical excitations, and at time
scales that will not create speed disadvantages). To make an analogy, think of
a memristor as a variable resistor where one is using current to very quickly
vary the resistance, rather than using a hand operated knob (which is relatively
slow). An optical memristor, following this line of reasoning, is then
something whose optical response can be changed (very quickly) using light.
So, for example, a high intensity light pulse can be used to set the optical
memristor’s “resistance” value, and a low intensity light pulse can then be
used to take the desired reading.
o The change should be thermally irreversible, and should occur only when
exposed to light of sufficient intensity (lower intensity light pulses can then be
4. used to take the reading that was intended). As a consequence of this the
device’s setting is non-volatile – it does not change if one turns the device off.
o The changes made to the device’s behavior should be reversible.
o The device’s setting should not be affected by taking a reading.
o The contrast between the two extremes of the device’s output should be
consistently unambiguous when measured.
o The optical response of the device should not vary very sharply at either
extreme of its parameters, but should rather have a smooth gradient so that its
intermediate responses are easily accessible/measurable. This will make it
possible to subdivide the range of parameters that the device can be operated
with into smaller steps. Ideally, the device’s response should be a straight line
through the origin (the gradient would have to be small enough so that the
output readings can be taken unambiguously), where the abscissa denotes the
state that the device has been set to and the ordinate denotes the resulting
response to a signal that comes in to get processed/modified.
o The device should be durable (i.e., it should have high fatigue resistance).
Organic photochromophores, for examples, have the desired reversibility, but
they break down after a few thousand transitions [4] – that is not desirable in a
device which might go through those transitions within a fraction of a second.
A practical optical memristor should not degrade with use from having its
setting rewritten.
• Fits the following requirements:
5. o The physical dimensions of the device should be small, so that a large number
of devices can be put on a small chip.
o The response time of the device should be small enough, as compared the
existing electrical memristor, to justify the expense of development and
implementation.
• Does not depend too much on technology that has not yet been invented:
o The materials and procedures for fabricating the device should ideally rely on
mature technologies, so as to allow widespread use.
o The methods required for characterization of the materials and devices should
ideally not require too many innovations in characterization technology or
paradigm so as to reduce the risk of creating a characterization method that
may not work for the items being tested.
It should be noted that while the memristors created by HP had variable resistances
(though they did not exactly fit all of the mathematical criteria that Chua put forth [2])
one does not need to dogmatically stick to Chua’s definitions to make a practical device.
In fact, one can choose any particular parameter one wants to (i.e., any one that one can)
modify dynamically in order to make a passive device whose behavior can be modified to
suit a dynamically changing requirement. Such a device would not be an optical
memristor in the literal sense of the word, but it would certainly fit the bill in the
figurative sense. So, one can make an optical memristor with a dynamically variable
absorption coefficient, or a dynamically variable refractive index, or a dynamically
variable polarization, etc.
6. Optical Memristor: The most promising route towards the realization of optical
memristance (after discarding photochromic switching materials, for fatigue problems,
and after discarding optically induced hysteresis in liquid crystals, for their lack of
thermal stability) led towards optically induced changes in a material’s dipole moment
and optical hysteresis: since magnetic materials have hysteresis curves and since light is
an electromagnetic wave it should be possible to alter the magnetic state of a magnetic
material using photonic excitation, and since magnetic states (in tapes, discs, etc.) are
thermally stable the optically induced magnetization changes should also be thermally
stable. It was found that Hansteen [5] and Stanciu [6] had already thought of this idea and
successfully tested it, with Rasing, Kimel, Kirilyuk, Hunderi, et al [7-8], for the purpose
of improving magneto-optical disc drives, which currently use a laser to irreversibly erase
data (through demagnetization) and use an externally applied magnetic field to write new
data. The primary difference between the kind of materials that [5-8] used and what an
optical memristor would best use would be that an optical memristor’s memristive
material (“memresponsive” would perhaps be more appropriate) would need to have the
kind of shallow hysteresis curves (which do not change rapidly towards either extreme of
memristance) that HP’s memristors had (the looping is not very important):
7. Figure 1: Shallow hysteresis curve for memristor, that does not change abruptly at either extreme [1]
A material meant for recording binary information, on the other hand, requires a
hysteresis curve that is steep, and sharp at the edges [9]:
Figure 2: Steep hysteresis curve for recording binary bits – changes very abruptly [9]
Optical memristance will also need to be very fast (to compete with the electrical
memristor). Since it will have to be fast now, and it will need to be competitive in the
future it cannot use an externally applied magnetic field to generate a magnetization
vector within the optical memristor’s material (after it has been erased by an ultrafast
laser that heats the material to its Curie temperature [10]) because despite
8. demagnetization being an ultrafast process “writing” a new magnetization vector into a
material can be done faster than is possible by the application of a magnetic field to a hot
magnetic material (the re-write frequency is hampered by the cooling time, and this
method requires the material to dissipate heat quickly for the next re-write, thus
introducing thermal management problems [11]). A faster process would be a nonthermal
optical control of magnetism [7]:
Figure 3: Time Scales for Magnetic and Optical Processes [7]
Other advantages of nonthermal control are that deterministic magnetization cannot be
achieved if an applied magnetic field pulse (no matter how strong) is shorter than 2 ps
[12], and that spontaneous magnetization reversal does not occur under a nonthermal
regime, which happens with magnetization of a material after thermalization to the Curie
temperature, as was found during single-pulse magneto-optic microscopy experiments
[13].
9. Mechanism of Nonthermal Optical Control of Magnetism: The magneto-optical
Faraday Effect [14] says that the magnetization vector of a material will affect light
propagating through that material (for example, linearly polarized light passing through a
magnetized material will act as if it went through a polarizer). The (opto-magnetic)
Inverse-Faraday Effect, predicted by Pitaevskii [15], predicted that nonthermal optical
control of magnetism would be possible (i.e., light could change the magnetization of a
magnetic material that it was passing through, if it was intense enough), but there used to
be doubts about that since producing the effect experimentally was challenging [16-18].
With the advent of ultrafast laser pulses, however, one can generate extremely strong
fields, and this has now enabled the experimental observation of the Inverse Faraday
Effect [7-8]. The Inverse Faraday Effect is essentially a photon-direction and spin
preserving stimulated Raman Effect. Essentially, an electron in a non-degenerate state
absorbs a higher energy photon – hω1 – (which has less energy than the material’s band
gap, thus eliminating the possibility of electronic transitions and thus, large thermal
effects) from a spectrally broad ultrashort pulse and goes through a spin flip in the ground
state (which takes up energy hω1- hω2) before going up into a virtual state (so it is as if
the electron was excited by a photon of lesser energy than the energy of the photon that it
absorbed – hω2); then this electron undergoes stimulated emission upon being hit by
another photon of energy hω2 and returns to the ground state. So, the number of photons
is conserved, but one photon has given up part of its energy in flipping an electron’s spin.
The hω1- hω2 value depends on the material and its temperature conditions.
10. Figure 4: Ultrafast spin-flip via the process of the stimulated Raman scattering [7].
Mechanism for Maximizing Coherent Quantum Control of Spins: A system will be
set up to shape the beam that will be incident on the opto-memristor material so that the
beam will have two peaks in the Fourier domain: one at hω1 and one at hω2. This will
reduce the number of photons with unwanted energy values that compete for interactions
with electrons.
11. Figure 5: Pulse shaping for reduce competition from photons of unwanted energy [7]
Controlling Magnetization Vector Precession – the Double Pulse Method: A single
pulse of circularly polarized light, in the absence of an external magnetic field will start
the magnetization vector of the optomemristor material precessing, and it will keep
precessing (with a speed dependent on the material properties, excitation parameters, and
the beam propagation direction relative to the crystallographic axes) until the electrons go
back to the ground state.
12. Figure 6: Taken from [7]
If the electrons are hit with a second pulse while they are precessing then there will either
be constructive or destructive interference of the spin precessions (if there is constructive
interference then the precession still eventually dies, but the second pulse just adds its
own amplitude and lifetime to the existing precession).
14. Figure 8: Taken from [7]
Optomemristor materials can be chosen for their precession speed, their spin-orbit
coupling resonant frequency, or their bandgap. Considering that the Radboud University
Nijmegen group [7-8] were able to use materials with different properties for their pulsed
experiments it should be possible to fabricate optomemristors with various sets of
advantages.
15. Optomemristance Measurements: Optomemristance, as described above,
can be measured using the Faraday Effect [14], i.e., by measuring the rotation of linearly
polarized light that has just passed through the sample, or by measuring the MOKE
(Magneto-Optic Kerr Effect) [19], which is the rotation of the polarization of linearly
polarized light that has just been reflected from the sample.
Optomemristor Material Schemes: For devices that will utilize MOKE the material can
be a ferromagnetic or an antiferromagnetic, or a maybe a ferrimagnetic garnet, or
crystalline thin film.
Figure 9: Possible configuration for optomemristor device utilizing MOKE for probing
16. For devices that will incorporate the Faraday Effect for taking readings garnets or
crystalline films can be used, as well as films with quantum dots (metallic, as well as
semiconductors, such as CdSe [20]) held in position by a polymer matrix, perhaps with
carbon nanotubes in the matrix, so as to enhance the Faraday rotation, since the carbon
nanotubes will take on the surrounding magnetic field [21].
Figure 10: Possible configuration for optomemristor device utilizing Faraday Rotation for probing
Optomemristor Detection Schemes: The probe readings that will be taken from the
optomemristor/optomagnetic memristor proposed here will be in the form of MOKE
rotation (Fig. 11) Faraday Effect (Fig. 12) rotations. Therefore, the detector system will
involve an analyzer that will block out scattered and transmitted light that has not
undergone rotation, so that the rotated light (linearly polarized probe beam light whose
17. polarization got rotated upon interaction with the sample) can excite photomultiplier
tubes (PMTs) [22] or APDs.
Figure 11: Typical MOKE Setup [13]
Figure 12: Typical Setup for Measuring Faraday Rotation [7]
18. During development stages for a new process (i.e., when the method is still in its early
stages) it may be necessary to probe not just the overall polarization rotation result, but
also rotation resulting from various depths of the sample. While MOKE systems will not
allow probing very deep into the material they can still be probed layer by layer, so to
speak. Such a system will be extremely useful for the development of an optical
memristor, especially since such a device has never really been tried, and the uniformity
of performance of material at the different depths may be important for ensuring that no
part of an optomemristor material undergoes undue stress (which would degrade device
longevity). A confocal MOKE microscope that could be used for such a purpose can be
found in [23]:
Figure 13: Confocal MOKE Microscope [23]
Microscopy Requirements: Given that the each mem
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