Cheng, Warren_Final Poster
•
1 like•216 views
1. Tip-enhanced near-field Raman spectroscopy (TERS) was used to study deformations induced in single-walled carbon nanotubes (SWCNTs) by an atomic force microscopy (AFM) tip. 2. A ~430nm horizontal defect was introduced using an AFM tip, and far-field and near-field Raman spectroscopy and AFM imaging were used to characterize the manipulated SWCNT. 3. The near-field TERS image revealed the manipulation region was about 5nm wide, indicating a bundled structure of 4-5 SWCNTs. Raman peak shifts and intensity changes provided information about the deformation's effect on the SWCNT's structure and properties.
Report
Share
Report
Share
Download to read offline
Recommended
LA SPECTROSCOPIE INFRAROUGE
The document discusses infrared spectroscopy. It begins by defining infrared spectroscopy and explaining that it involves absorption of infrared radiation which causes transitions between vibration and rotation energy levels of molecules. It then describes the main types of spectrometers used: dispersive spectrometers and Fourier transform infrared (FT-IR) spectrometers. FT-IR spectrometers have advantages over dispersive spectrometers as they allow simultaneous measurement of all wavelengths using an interferometer. The document goes on to discuss techniques for examining samples by IR spectroscopy and interpretation of IR spectra.
Optical Communication unit 1 (part 1)
This document outlines the objectives and outcomes of the course EC8751-Optical Communication. The key objectives are to study optical fiber modes, materials, fabrication, transmission characteristics, optical sources and detectors, receiver systems, and measurements. The outcomes are to understand basic fiber elements, analyze dispersion and polarization techniques, design optical components, construct receiver systems, and design communication systems and networks. It provides textbook references and outlines topics like fiber structure, types, applications, generation of optical fiber communication systems, and fiber materials.
OPTICAL COMMUNICATION Unit 5
The document discusses digital transmission systems and coherent optical communications. It covers the following key points:
1) It describes the components and operation of optical receivers, including the challenges of detecting weak signals and making decisions on transmitted data. Error sources like intersymbol interference are also discussed.
2) Bit error rate and probability of error are defined, and formulas for calculating BER under Gaussian noise are provided.
3) Eye diagrams are introduced as a way to visualize signal quality over time. Factors like timing jitter and noise amplitude are described.
4) Coherent optical receivers are overviewed, including their advantages for high data rates and constellations. Challenges in carrier recovery using optical phase-locked
Photonics devices
Photonics devices use photons to transmit, control, manipulate and store data. They offer benefits like greater energy savings and communication distances due to their unique characteristics, such as being less sensitive to interference. Light-emitting diodes (LEDs) are semiconductor light sources used as indicator lamps and increasingly for lighting. They have advantages over other light sources like lower energy use, longer lifetimes, and smaller size. Photodiodes are PN junction diodes designed to detect photons and convert light into an electrical current. Laser diodes are semiconductor devices that produce coherent light when current passes through and are used to convert electrical signals into light signals.
Birefringence measurements
This document discusses techniques for measuring birefringence in optical fibers. Birefringence is the difference in refractive indices for different polarization states. The beat length is the distance over which a state of polarization repeats and can be used to characterize birefringence. Several methods are presented: Rayleigh scattering detects polarization-dependent scattering patterns; magneto-optic modulation applies a magnetic field to induce birefringence; prism coupling couples light out of the fiber at angles related to propagation constants; and wavelength scanning analyzes modulation patterns with wavelength to determine beat length and birefringence. Each technique is described along with relevant setup diagrams.
Lecture22 non linear fiber optics
This document provides an overview of non-linear fiber optics. It discusses how the refractive index of an optical fiber becomes dependent on optical intensity at higher powers, leading to non-linear propagation effects. Key topics covered include Kerr non-linearity, frequency mixing via the third-order susceptibility, derivation of the non-linear Schrodinger equation, and implications for wavelength division multiplexing transmission. The document explains that non-linear effects can be easily observed at low powers in fibers due to the high intensity confinement over long interaction lengths.
FTIR vs Dispersive IR
This document compares and contrasts the properties of dispersive infrared (IR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. It discusses seven key differences between the two techniques: 1) components and movement, 2) calibration, 3) stray light effects, 4) number of frequencies detected simultaneously, 5) scan speed, 6) effects of IR radiation from the sample, and 7) advantages of single beam versus double beam optics.
Neutron radiography
Neutron radiography uses neutron beams to produce images of the internal structure and composition of objects. Neutrons are produced, moderated to the desired energy level, collimated into a beam, and passed through an object. A conversion screen then converts the neutrons into other radiation that exposes film or is detected digitally to create an image based on the attenuation of neutrons within the object. Neutron radiography provides information complementary to X-rays as different elements absorb neutrons differently, allowing materials like organic compounds or water to be visualized within dense metallic structures.
Recommended
LA SPECTROSCOPIE INFRAROUGE
The document discusses infrared spectroscopy. It begins by defining infrared spectroscopy and explaining that it involves absorption of infrared radiation which causes transitions between vibration and rotation energy levels of molecules. It then describes the main types of spectrometers used: dispersive spectrometers and Fourier transform infrared (FT-IR) spectrometers. FT-IR spectrometers have advantages over dispersive spectrometers as they allow simultaneous measurement of all wavelengths using an interferometer. The document goes on to discuss techniques for examining samples by IR spectroscopy and interpretation of IR spectra.
Optical Communication unit 1 (part 1)
This document outlines the objectives and outcomes of the course EC8751-Optical Communication. The key objectives are to study optical fiber modes, materials, fabrication, transmission characteristics, optical sources and detectors, receiver systems, and measurements. The outcomes are to understand basic fiber elements, analyze dispersion and polarization techniques, design optical components, construct receiver systems, and design communication systems and networks. It provides textbook references and outlines topics like fiber structure, types, applications, generation of optical fiber communication systems, and fiber materials.
OPTICAL COMMUNICATION Unit 5
The document discusses digital transmission systems and coherent optical communications. It covers the following key points:
1) It describes the components and operation of optical receivers, including the challenges of detecting weak signals and making decisions on transmitted data. Error sources like intersymbol interference are also discussed.
2) Bit error rate and probability of error are defined, and formulas for calculating BER under Gaussian noise are provided.
3) Eye diagrams are introduced as a way to visualize signal quality over time. Factors like timing jitter and noise amplitude are described.
4) Coherent optical receivers are overviewed, including their advantages for high data rates and constellations. Challenges in carrier recovery using optical phase-locked
Photonics devices
Photonics devices use photons to transmit, control, manipulate and store data. They offer benefits like greater energy savings and communication distances due to their unique characteristics, such as being less sensitive to interference. Light-emitting diodes (LEDs) are semiconductor light sources used as indicator lamps and increasingly for lighting. They have advantages over other light sources like lower energy use, longer lifetimes, and smaller size. Photodiodes are PN junction diodes designed to detect photons and convert light into an electrical current. Laser diodes are semiconductor devices that produce coherent light when current passes through and are used to convert electrical signals into light signals.
Birefringence measurements
This document discusses techniques for measuring birefringence in optical fibers. Birefringence is the difference in refractive indices for different polarization states. The beat length is the distance over which a state of polarization repeats and can be used to characterize birefringence. Several methods are presented: Rayleigh scattering detects polarization-dependent scattering patterns; magneto-optic modulation applies a magnetic field to induce birefringence; prism coupling couples light out of the fiber at angles related to propagation constants; and wavelength scanning analyzes modulation patterns with wavelength to determine beat length and birefringence. Each technique is described along with relevant setup diagrams.
Lecture22 non linear fiber optics
This document provides an overview of non-linear fiber optics. It discusses how the refractive index of an optical fiber becomes dependent on optical intensity at higher powers, leading to non-linear propagation effects. Key topics covered include Kerr non-linearity, frequency mixing via the third-order susceptibility, derivation of the non-linear Schrodinger equation, and implications for wavelength division multiplexing transmission. The document explains that non-linear effects can be easily observed at low powers in fibers due to the high intensity confinement over long interaction lengths.
FTIR vs Dispersive IR
This document compares and contrasts the properties of dispersive infrared (IR) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. It discusses seven key differences between the two techniques: 1) components and movement, 2) calibration, 3) stray light effects, 4) number of frequencies detected simultaneously, 5) scan speed, 6) effects of IR radiation from the sample, and 7) advantages of single beam versus double beam optics.
Neutron radiography
Neutron radiography uses neutron beams to produce images of the internal structure and composition of objects. Neutrons are produced, moderated to the desired energy level, collimated into a beam, and passed through an object. A conversion screen then converts the neutrons into other radiation that exposes film or is detected digitally to create an image based on the attenuation of neutrons within the object. Neutron radiography provides information complementary to X-rays as different elements absorb neutrons differently, allowing materials like organic compounds or water to be visualized within dense metallic structures.
Laser
1) LASERs use the process of stimulated emission to generate coherent light amplification. Light amplification occurs as photons collide with excited atoms, causing them to emit additional photons.
2) Optical cavities formed by mirrors provide positive feedback by reflecting photons back and forth through the gain medium, allowing for laser oscillation to occur. Semiconductor injection LASERs use a PN junction to electrically pump the active region.
3) Advances have led to heterostructure, quantum well, and quantum dot LASER designs that provide improved carrier and optical confinement for lower threshold currents and increased output. Different LASER structures like gain-guided, index-guided, single mode, and distributed Bragg reflector designs further enhance
FIBER BRAGG GRATING AND ITS APPLICATIONS OPTICAL SWITCH OPTO-ELECTRONIC INTE...
Includes Fiber Bragg Grating, Optical Switch , Opto-electronic integrated circuit , Slab and Strip Waveguide
Birefringence and Bragg grating control in femtosecond laser written optical ...
Birefringence and Bragg grating control in femtosecond laser written optical ...Luís André Fernandes
This document summarizes research on controlling birefringence and Bragg gratings using femtosecond laser writing in optical circuits. It describes using this technique to fabricate integrated wave plates with polarization contrast up to 35 dB and polarization beam splitters with extinction ratios from 19-24 dB. The research demonstrates controlling birefringence from 10-6 to 10-4 by manipulating laser stress fields and polarization during writing. Future work aims to reduce device sizes and losses for applications in quantum photonics and sensing.FTIR
This document discusses Fourier transform infrared spectroscopy (FTIR). It begins by defining a spectrometer and describing how FTIR obtains infrared spectra using an interferometer and Fourier transform. It then explains the basic components and working of an FTIR, including advantages like higher sensitivity, accuracy and resolution compared to dispersion spectrometers. Specific advantages like Fellgett's multiplex advantage and improved signal-to-noise are covered. Finally, common applications of FTIR are listed.
OPTICAL COMMUNICATION Unit 4
The document discusses optical coupling between light sources and optical fibers. It defines coupling efficiency as the ratio of power coupled into the fiber to power emitted from the source. Radiance and radiation patterns of different light sources are described. Expressions are provided for calculating the power coupled from a source to a fiber based on the source and fiber parameters. Methods to improve coupling efficiency such as lensing are also discussed. The document also covers topics like fiber-to-fiber coupling loss, mechanical misalignment loss, and fiber end defects.
Microstrip antennas
This document provides an overview of microstrip antennas, including:
1) Microstrip antennas are low profile, lightweight, and inexpensive to manufacture. They have limitations such as low efficiency and narrow bandwidth.
2) Microstrip antennas generally consist of a metallic patch on a dielectric substrate with a ground plane. The substrate properties, such as thickness and dielectric constant, impact antenna performance.
3) Feeding techniques include microstrip lines, coaxial probes, aperture coupling, and proximity coupling. Surface waves can reduce efficiency and must be considered in substrate selection.
Time lens
This document describes a silicon chip-based time lens that can capture and measure ultrafast optical signals in real time. It works by using a third-order nonlinear optical process called four-wave mixing to impart a quadratic phase shift to an optical signal, analogous to how a spatial lens works. This allows the temporal profile of an optical waveform to be mapped to the spectral domain, where it can be measured with high resolution using a spectrometer. The silicon time lens achieved a resolution of 220 femtoseconds over a recording length of over 100 picoseconds. Integrating such photonics components on a silicon chip paves the way for developing ultracompact, high-performance oscilloscopes and other devices for measuring transient optical and electronic signals
Optical fiber communication Part 1 Optical Fiber Fundamentals
Optical fiber systems grew from combination of semiconductor technology, which provided necessary light sources and photodetectors and optical waveguide technology. It has significant inherent advantages over conventional copper systems- low transmission loss, wide BW, light weight and size, immunity to interferences, signal security to name a few. One principle characteristic of optical fiber is its attenuation as a function of wavelength. Hence it is operated in two major low attenuation wavelength windows 800-900nm and 1100-1600nm . Light travels inside optical fiber waveguide on principle of total internal reflection. Fiber is available as single mode and multiple mode, step index and graded index depending on applications and expenditures. Principle of fiber can be understood by ray theory or mode theory. ...
Laser rate equations
Laser diode have to have a specific architecture in order to optimize the laser light leaving the waveguide. There are various factors that are to be precisely noted and put into certain equations in order to calculate the differential quantum efficiency and to improvise the design of the diode lasers. The slides explain about reservoir analogy, threshold and gain and photon density as well as carrier density rate equations. Glad if it helps :)
Substrate Integrated Waveguide Based Leaky-Wave Antenna
This document describes a novel leaky-wave antenna design based on a substrate integrated waveguide (SIW) with non-uniform slots. The key aspects are:
1) The antenna uses a SIW structure with slots of varying widths (non-uniform) to reduce side lobes and improve radiation efficiency compared to previous uniform slot designs.
2) Simulation results show the design has improved reflection coefficient (below -10 dB) and scans from broadside to near end-fire as frequency increases from 10.3 GHz to 12 GHz.
3) Radiation patterns at different frequencies within the band demonstrate the beam scanning ability of the design.
gain & directivity enhancement of patch antenna using metamaterial
This document discusses several papers on using metamaterials to enhance the gain and directivity of patch antennas. It first provides an overview of metamaterials and their properties. It then summarizes three research papers that designed different metamaterial structures to act as superstrates above microstrip patch antennas. All three papers were able to significantly increase the gain of the patch antennas using near-zero index metamaterial superstrates designed with unit cells like the Jerusalem Cross, Double S-shape, and mnz-metasurfaces. Simulation results from the papers showed enhanced realized gains between 2.3 to 7.65 dB compared to reference patch antennas without metamaterial loading.
Febry perot sensor
The document discusses the Fabry-Perot interferometer, an optical sensor used to measure small displacements. It consists of two parallel mirrors separated by a cavity, and works by detecting changes in the frequency of light transmitted through the cavity when the mirror spacing changes due to environmental factors like pressure, strain, or temperature. Measurements with an accuracy comparable to the wavelength of light are possible. Applications include pressure sensing, where pressure deflects a diaphragm and alters the cavity length. Advantages are small size, accuracy, and insensitivity to environmental effects. Disadvantages include high cost and unsuitability for high pressures.
Optical fiber laser
Optical fiber lasers operate based on stimulated emission of photons from excited atoms or molecules within an active medium, such as rare earth doped silica fibers. They were first developed in the 1960s and have several advantages over solid-state lasers including high beam quality, efficiency, and thermal management. Fiber lasers are fabricated by first making a preform via modified chemical vapor deposition to dope the silica with rare earth ions. The preform is then drawn into an optical fiber, which can be structured using fiber Bragg gratings to form the laser cavity. Applications include materials processing, telecommunications, medicine, and directed energy weapons.
Chapter 2c
Graded index (GRIN) optical fibers have a refractive index that decreases continuously from the core center to the cladding. This results in curved ray paths inside the core rather than straight lines, reducing intermodal dispersion. The optimal refractive index profile for minimizing dispersion is parabolic. Attenuation in optical fibers is due to various factors including material absorption, scattering, and bending losses. Rayleigh scattering increases at shorter wavelengths, while absorption peaks exist for hydroxyl and metal impurities.
Optical communication unit 1
The document provides an introduction to optical fibers and optical communication systems. It discusses the basic elements of an optical fiber transmission link including the transmitter, optical fiber, and receiver. It describes the major components of an optical fiber link including the core, cladding, and buffer. It also summarizes the different types of optical fibers including single-mode fibers, multimode step-index fibers, and multimode graded-index fibers. The refractive index profiles and light propagation in these fiber types are explained.
Laser Communications
Laser communication is well-suited for small spacecraft due to the small optics required. It uses modulation of a laser beam to transmit information, with technologies like laser diodes and sensitive detectors enabling communication over long distances using low power. Key components of a laser communication system include the laser source, modulation techniques, beam optics, photon sensors like CCDs or PMTs, and tracking systems to point the receiver at the transmitter.
optical fiber and laser
1. Lasers work by stimulating the emission of coherent light through the process of stimulated emission. A laser provides a coherent beam of light that is highly focused and monochromatic. ND:YAG lasers use neodymium-doped yttrium aluminium garnet as the lasing medium.
2. Optical fibers transmit light through the process of total internal reflection. They have advantages over electrical cables including higher bandwidth, immunity to interference, safety, and security. Multi-mode fibers have larger cores than single-mode fibers.
3. Numerical aperture characterizes the light-gathering ability of an optical fiber, describing the range of angles at which light can enter or exit.
ICACC Presentation
This document discusses using metamaterials to improve wireless power transfer. It describes how Nikola Tesla experimented with wireless power transmission in the late 1800s. Metamaterials are periodic structures that can achieve unusual electromagnetic properties not found in nature. When placed above a microstrip patch antenna array, metamaterials were shown to increase the antenna gain, radiation efficiency, and total efficiency compared to the antenna array alone. The improved antenna performance when coupled with metamaterials allows for increased wireless power transmission range for applications such as smart grids.
TIRF MICROSCOPE
Total internal reflection fluorescence microscopy (TIRFM) uses an evanescent wave created by total internal reflection at the interface between two media of different refractive indices to selectively excite fluorescent molecules within 100 nm of the interface. There are three main approaches to TIRFM: prism-based uses a prism to attain the critical angle for total internal reflection and provides the purest evanescent wave but limits sample access; objective-based directs light through a high-NA objective lens to change the angle of incidence and penetration depth but generates more stray light; lightguide-based provides independent excitation and emission paths for better signal-to-background ratio and is well-suited for multicolor experiments. TIRFM is used to
Physics nanophotonics
This document discusses nanophotonics and its applications. It begins by defining nanophotonics as the study of light behavior on the nanometer scale, including interactions between light and particles. It then discusses several nanophotonics technologies like near-field scanning optical microscopy and surface plasmon optics. The document also outlines several advantages of nanophotonics, such as enabling enormous data transmission rates and high optical memory storage density. It concludes by discussing some applications of nanophotonics like NEMS (nanoelectromechanical systems) devices that integrate electrical and mechanical functionality on the nanoscale.
Near field scanning optical microscopy
NSOM/SNOM is a scanning probe microscopy technique that can achieve higher resolution than far-field optical microscopy, around 50 nm. It works by exploiting evanescent waves from a sample that are detected using a probe placed within the near-field zone. PINEM is a related technique that uses ultrafast electron pulses synchronized with optical pulses to map photon-electron interactions and image plasmonic fields with high spatiotemporal resolution. Both techniques allow studying nanoscale optical and material properties with applications in nanotechnology, biophysics, and materials science.
Raman Analysis of Carbon Nanostructures draft3
This document summarizes a student's work analyzing carbon nanostructures using Raman spectroscopy. The student developed MATLAB tools to process Raman spectral data and fit peaks. They aimed to collect Raman images of single-walled carbon nanotubes on silicon wafers. Additionally, the student sought to develop atomic force microscopy and tip-enhanced Raman spectroscopy techniques to simultaneously obtain Raman and surface topology data with nanoscale resolution. Future work would involve continuing to improve analysis tools and applying various microscopy methods to research on carbon nanotechnology and standardization.
More Related Content
What's hot
Laser
1) LASERs use the process of stimulated emission to generate coherent light amplification. Light amplification occurs as photons collide with excited atoms, causing them to emit additional photons.
2) Optical cavities formed by mirrors provide positive feedback by reflecting photons back and forth through the gain medium, allowing for laser oscillation to occur. Semiconductor injection LASERs use a PN junction to electrically pump the active region.
3) Advances have led to heterostructure, quantum well, and quantum dot LASER designs that provide improved carrier and optical confinement for lower threshold currents and increased output. Different LASER structures like gain-guided, index-guided, single mode, and distributed Bragg reflector designs further enhance
FIBER BRAGG GRATING AND ITS APPLICATIONS OPTICAL SWITCH OPTO-ELECTRONIC INTE...
Includes Fiber Bragg Grating, Optical Switch , Opto-electronic integrated circuit , Slab and Strip Waveguide
Birefringence and Bragg grating control in femtosecond laser written optical ...
Birefringence and Bragg grating control in femtosecond laser written optical ...Luís André Fernandes
This document summarizes research on controlling birefringence and Bragg gratings using femtosecond laser writing in optical circuits. It describes using this technique to fabricate integrated wave plates with polarization contrast up to 35 dB and polarization beam splitters with extinction ratios from 19-24 dB. The research demonstrates controlling birefringence from 10-6 to 10-4 by manipulating laser stress fields and polarization during writing. Future work aims to reduce device sizes and losses for applications in quantum photonics and sensing.FTIR
This document discusses Fourier transform infrared spectroscopy (FTIR). It begins by defining a spectrometer and describing how FTIR obtains infrared spectra using an interferometer and Fourier transform. It then explains the basic components and working of an FTIR, including advantages like higher sensitivity, accuracy and resolution compared to dispersion spectrometers. Specific advantages like Fellgett's multiplex advantage and improved signal-to-noise are covered. Finally, common applications of FTIR are listed.
OPTICAL COMMUNICATION Unit 4
The document discusses optical coupling between light sources and optical fibers. It defines coupling efficiency as the ratio of power coupled into the fiber to power emitted from the source. Radiance and radiation patterns of different light sources are described. Expressions are provided for calculating the power coupled from a source to a fiber based on the source and fiber parameters. Methods to improve coupling efficiency such as lensing are also discussed. The document also covers topics like fiber-to-fiber coupling loss, mechanical misalignment loss, and fiber end defects.
Microstrip antennas
This document provides an overview of microstrip antennas, including:
1) Microstrip antennas are low profile, lightweight, and inexpensive to manufacture. They have limitations such as low efficiency and narrow bandwidth.
2) Microstrip antennas generally consist of a metallic patch on a dielectric substrate with a ground plane. The substrate properties, such as thickness and dielectric constant, impact antenna performance.
3) Feeding techniques include microstrip lines, coaxial probes, aperture coupling, and proximity coupling. Surface waves can reduce efficiency and must be considered in substrate selection.
Time lens
This document describes a silicon chip-based time lens that can capture and measure ultrafast optical signals in real time. It works by using a third-order nonlinear optical process called four-wave mixing to impart a quadratic phase shift to an optical signal, analogous to how a spatial lens works. This allows the temporal profile of an optical waveform to be mapped to the spectral domain, where it can be measured with high resolution using a spectrometer. The silicon time lens achieved a resolution of 220 femtoseconds over a recording length of over 100 picoseconds. Integrating such photonics components on a silicon chip paves the way for developing ultracompact, high-performance oscilloscopes and other devices for measuring transient optical and electronic signals
Optical fiber communication Part 1 Optical Fiber Fundamentals
Optical fiber systems grew from combination of semiconductor technology, which provided necessary light sources and photodetectors and optical waveguide technology. It has significant inherent advantages over conventional copper systems- low transmission loss, wide BW, light weight and size, immunity to interferences, signal security to name a few. One principle characteristic of optical fiber is its attenuation as a function of wavelength. Hence it is operated in two major low attenuation wavelength windows 800-900nm and 1100-1600nm . Light travels inside optical fiber waveguide on principle of total internal reflection. Fiber is available as single mode and multiple mode, step index and graded index depending on applications and expenditures. Principle of fiber can be understood by ray theory or mode theory. ...
Laser rate equations
Laser diode have to have a specific architecture in order to optimize the laser light leaving the waveguide. There are various factors that are to be precisely noted and put into certain equations in order to calculate the differential quantum efficiency and to improvise the design of the diode lasers. The slides explain about reservoir analogy, threshold and gain and photon density as well as carrier density rate equations. Glad if it helps :)
Substrate Integrated Waveguide Based Leaky-Wave Antenna
This document describes a novel leaky-wave antenna design based on a substrate integrated waveguide (SIW) with non-uniform slots. The key aspects are:
1) The antenna uses a SIW structure with slots of varying widths (non-uniform) to reduce side lobes and improve radiation efficiency compared to previous uniform slot designs.
2) Simulation results show the design has improved reflection coefficient (below -10 dB) and scans from broadside to near end-fire as frequency increases from 10.3 GHz to 12 GHz.
3) Radiation patterns at different frequencies within the band demonstrate the beam scanning ability of the design.
gain & directivity enhancement of patch antenna using metamaterial
This document discusses several papers on using metamaterials to enhance the gain and directivity of patch antennas. It first provides an overview of metamaterials and their properties. It then summarizes three research papers that designed different metamaterial structures to act as superstrates above microstrip patch antennas. All three papers were able to significantly increase the gain of the patch antennas using near-zero index metamaterial superstrates designed with unit cells like the Jerusalem Cross, Double S-shape, and mnz-metasurfaces. Simulation results from the papers showed enhanced realized gains between 2.3 to 7.65 dB compared to reference patch antennas without metamaterial loading.
Febry perot sensor
The document discusses the Fabry-Perot interferometer, an optical sensor used to measure small displacements. It consists of two parallel mirrors separated by a cavity, and works by detecting changes in the frequency of light transmitted through the cavity when the mirror spacing changes due to environmental factors like pressure, strain, or temperature. Measurements with an accuracy comparable to the wavelength of light are possible. Applications include pressure sensing, where pressure deflects a diaphragm and alters the cavity length. Advantages are small size, accuracy, and insensitivity to environmental effects. Disadvantages include high cost and unsuitability for high pressures.
Optical fiber laser
Optical fiber lasers operate based on stimulated emission of photons from excited atoms or molecules within an active medium, such as rare earth doped silica fibers. They were first developed in the 1960s and have several advantages over solid-state lasers including high beam quality, efficiency, and thermal management. Fiber lasers are fabricated by first making a preform via modified chemical vapor deposition to dope the silica with rare earth ions. The preform is then drawn into an optical fiber, which can be structured using fiber Bragg gratings to form the laser cavity. Applications include materials processing, telecommunications, medicine, and directed energy weapons.
Chapter 2c
Graded index (GRIN) optical fibers have a refractive index that decreases continuously from the core center to the cladding. This results in curved ray paths inside the core rather than straight lines, reducing intermodal dispersion. The optimal refractive index profile for minimizing dispersion is parabolic. Attenuation in optical fibers is due to various factors including material absorption, scattering, and bending losses. Rayleigh scattering increases at shorter wavelengths, while absorption peaks exist for hydroxyl and metal impurities.
Optical communication unit 1
The document provides an introduction to optical fibers and optical communication systems. It discusses the basic elements of an optical fiber transmission link including the transmitter, optical fiber, and receiver. It describes the major components of an optical fiber link including the core, cladding, and buffer. It also summarizes the different types of optical fibers including single-mode fibers, multimode step-index fibers, and multimode graded-index fibers. The refractive index profiles and light propagation in these fiber types are explained.
Laser Communications
Laser communication is well-suited for small spacecraft due to the small optics required. It uses modulation of a laser beam to transmit information, with technologies like laser diodes and sensitive detectors enabling communication over long distances using low power. Key components of a laser communication system include the laser source, modulation techniques, beam optics, photon sensors like CCDs or PMTs, and tracking systems to point the receiver at the transmitter.
optical fiber and laser
1. Lasers work by stimulating the emission of coherent light through the process of stimulated emission. A laser provides a coherent beam of light that is highly focused and monochromatic. ND:YAG lasers use neodymium-doped yttrium aluminium garnet as the lasing medium.
2. Optical fibers transmit light through the process of total internal reflection. They have advantages over electrical cables including higher bandwidth, immunity to interference, safety, and security. Multi-mode fibers have larger cores than single-mode fibers.
3. Numerical aperture characterizes the light-gathering ability of an optical fiber, describing the range of angles at which light can enter or exit.
ICACC Presentation
This document discusses using metamaterials to improve wireless power transfer. It describes how Nikola Tesla experimented with wireless power transmission in the late 1800s. Metamaterials are periodic structures that can achieve unusual electromagnetic properties not found in nature. When placed above a microstrip patch antenna array, metamaterials were shown to increase the antenna gain, radiation efficiency, and total efficiency compared to the antenna array alone. The improved antenna performance when coupled with metamaterials allows for increased wireless power transmission range for applications such as smart grids.
TIRF MICROSCOPE
Total internal reflection fluorescence microscopy (TIRFM) uses an evanescent wave created by total internal reflection at the interface between two media of different refractive indices to selectively excite fluorescent molecules within 100 nm of the interface. There are three main approaches to TIRFM: prism-based uses a prism to attain the critical angle for total internal reflection and provides the purest evanescent wave but limits sample access; objective-based directs light through a high-NA objective lens to change the angle of incidence and penetration depth but generates more stray light; lightguide-based provides independent excitation and emission paths for better signal-to-background ratio and is well-suited for multicolor experiments. TIRFM is used to
Physics nanophotonics
This document discusses nanophotonics and its applications. It begins by defining nanophotonics as the study of light behavior on the nanometer scale, including interactions between light and particles. It then discusses several nanophotonics technologies like near-field scanning optical microscopy and surface plasmon optics. The document also outlines several advantages of nanophotonics, such as enabling enormous data transmission rates and high optical memory storage density. It concludes by discussing some applications of nanophotonics like NEMS (nanoelectromechanical systems) devices that integrate electrical and mechanical functionality on the nanoscale.
What's hot (20)
FIBER BRAGG GRATING AND ITS APPLICATIONS OPTICAL SWITCH OPTO-ELECTRONIC INTE...
FIBER BRAGG GRATING AND ITS APPLICATIONS OPTICAL SWITCH OPTO-ELECTRONIC INTE...
Birefringence and Bragg grating control in femtosecond laser written optical ...
Birefringence and Bragg grating control in femtosecond laser written optical ...
Optical fiber communication Part 1 Optical Fiber Fundamentals
Optical fiber communication Part 1 Optical Fiber Fundamentals
Substrate Integrated Waveguide Based Leaky-Wave Antenna
Substrate Integrated Waveguide Based Leaky-Wave Antenna
gain & directivity enhancement of patch antenna using metamaterial
gain & directivity enhancement of patch antenna using metamaterial
Similar to Cheng, Warren_Final Poster
Near field scanning optical microscopy
NSOM/SNOM is a scanning probe microscopy technique that can achieve higher resolution than far-field optical microscopy, around 50 nm. It works by exploiting evanescent waves from a sample that are detected using a probe placed within the near-field zone. PINEM is a related technique that uses ultrafast electron pulses synchronized with optical pulses to map photon-electron interactions and image plasmonic fields with high spatiotemporal resolution. Both techniques allow studying nanoscale optical and material properties with applications in nanotechnology, biophysics, and materials science.
Raman Analysis of Carbon Nanostructures draft3
This document summarizes a student's work analyzing carbon nanostructures using Raman spectroscopy. The student developed MATLAB tools to process Raman spectral data and fit peaks. They aimed to collect Raman images of single-walled carbon nanotubes on silicon wafers. Additionally, the student sought to develop atomic force microscopy and tip-enhanced Raman spectroscopy techniques to simultaneously obtain Raman and surface topology data with nanoscale resolution. Future work would involve continuing to improve analysis tools and applying various microscopy methods to research on carbon nanotechnology and standardization.
Optical Antenna
Optical antennas are devices designed to efficiently convert between propagating optical radiation and localized energy. Like radio frequency antennas, optical antennas can increase the interaction area of local absorbers or emitters with free radiation. Key aspects of optical antennas include their operation based on plasmonics and impedance matching. They can be fabricated using electron beam lithography or focused ion beam milling at the nanoscale. Applications include imaging, photovoltaics, and coherent control. Optical antennas provide opportunities for new optoelectronic architectures and devices by controlling light-matter interactions at the nanoscale.
Dario Scotto - Detecting and Imaging Magneto-Optically Trapped Rubidium-85 Io...
The document describes a proposed design for trapping and imaging rubidium-85 ions using near-field scanning optical microscopy techniques. The design involves using three orthogonal laser beams to form an optical molasses trap for cooling rubidium ions. This trap will be assisted by an anti-Helmholtz coil pair to create a magneto-optical trap. Tapered optical fibers etched with hydrofluoric acid will be used as probes in near-field scanning optical microscopy to detect and image the trapped ions with high resolution. Fluorescence detection of the trapped ions will aim to optimize the signal-to-noise ratio using lock-in amplification.
Sachin new ftir
The document discusses Fourier transform infrared spectroscopy (FTIR). It begins by explaining the basic principles of FTIR including how a Fourier transform is used to convert infrared absorption data into a spectrum. It then describes key components of an FTIR instrument and how it works. The document outlines advantages such as high resolution and speed of analysis. Applications including structure determination and identification of organic compounds are also mentioned.
Theory of surface plasmon polaritons
- Surface plasmon polaritons are electromagnetic waves that propagate along the interface between a metal and a dielectric material. They arise from the coupling of incident light to oscillations of surface electrons known as surface plasmons.
- Surface plasmon polaritons can be excited through techniques like prism coupling using either the Otto or Kretschmann configurations, which use evanescent waves to overcome the momentum mismatch between incident light and surface plasmons.
- Applications of surface plasmon resonance include ultrasensitive biosensing, fluorescence imaging, catalysis, and phototherapy due to the ability of surface plasmons to concentrate electromagnetic fields at subwavelength scales.
Characterization of nanopartical
This document discusses various characterization techniques for nanoparticles. It describes microscopy methods like scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning tunneling microscopy (STM) that can be used to determine nanoparticle size, shape, composition and crystalline structure at high resolution. Spectroscopy methods like X-ray diffraction (XRD), small angle X-ray scattering (SAXS), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy, and Fourier transform infrared spectroscopy (FT-IR) are also outlined for analyzing nanoparticle properties. The key techniques of SEM, TEM, XRD and SAXS are then explained in more detail regarding their basic principles and what types of nanoparticle information can be obtained
ELECTRON MICROSCOPY (TEM & SEM)
The document discusses electron microscopes and their components and operation. Electron microscopes use a beam of electrons instead of light to examine objects at a very fine scale. There are two main types - scanning electron microscopes (SEM) and transmission electron microscopes (TEM). SEMs produce higher resolution images than optical microscopes and work by scanning a focused beam of electrons across a sample. TEMs require electron-transparent samples and work by transmitting electrons through a sample to form an image. Both types of electron microscopes have advanced scientific understanding by allowing observation of microscopic structures.
Raman spectroscopy for nanomaterials
1. Raman spectroscopy can be used to analyze nanomaterials but has low sensitivity for nanoparticles due to inefficient scattering. Surface enhanced Raman spectroscopy (SERS) overcomes this by using rough metal surfaces or nanoparticles to greatly enhance the Raman signal.
2. There are two main enhancement mechanisms in SERS - electromagnetic enhancement from localized surface plasmons and chemical enhancement from charge transfer. Optimizing substrates, laser wavelength, and adsorbate molecules is important for strong SERS signals.
3. Tip enhanced Raman spectroscopy (TERS) uses a metal tip to confine light and further increase the electric field, allowing nanoscale spatial resolution beyond the diffraction limit.
Photonic Materials
Photonic materials manipulate photons to achieve certain functions. Photonic crystals are a type of photonic material that displays unusual properties in interacting with light due to a periodic modulation of refractive index. They can trap light in cavities and waveguides by creating photonic band gaps that prevent light from propagating in certain directions. Potential applications of photonic crystals include photonic integrated circuits, lasers, sensors, and replacing conventional optical fibers.
Ir
- Infrared spectroscopy analyzes the absorption of infrared radiation by molecules to determine their structure.
- Infrared radiation is passed through a sample, and the wavelengths absorbed are measured to produce an infrared spectrum.
- The spectrum corresponds to the vibrational and rotational frequencies of functional groups in the molecule, allowing the structure to be deduced.
Dr. jaishree nmr instrumentation
Nuclear magnetic resonance (NMR) spectroscopy uses powerful magnets and radiofrequency energy to characterize organic molecules. NMR spectrometers consist of a magnet to align nuclear spins, a radiofrequency source to excite spins, and a detector to measure the energy absorbed. The main components are the magnet, probe, and electronics for excitation and detection. NMR provides information about carbon-hydrogen frameworks by measuring the energy required for nuclei to change spin orientation in the magnetic field.
Scanning electron microscope
This document provides an overview of the scanning electron microscope (SEM). It describes that the SEM uses a focused beam of electrons to scan the surface of a sample to produce images of its surface topography and composition. The key components of an SEM include an electron gun, magnetic lenses, scanning coils, electron detectors, and a cathode ray tube display. SEMs offer higher magnification, greater depth of field, better resolution, and compositional analysis compared to optical microscopes. Example applications of SEMs include examining the structures of large specimens and samples across various fields like biology, materials science, and engineering.
Fiber lasers and optoelectronic devices based on few layers of graphene - Luc...
This document summarizes work on fiber lasers and discusses potential optoelectronic devices using graphene. It first describes previous work actively mode-locking Erbium fiber lasers over meters and kilometers in length, including a 50km ultralong fiber laser. It then discusses future interests in using graphene for optical modulators, including prototypes of an electroabsorption modulator based on monolayer graphene and a double-layer graphene modulator. A theoretical Mach-Zehnder modulator using 8 graphene layers is also presented, showing the potential for high modulation efficiency and extinction ratio. The document concludes by stating research interests in developing graphene-based optoelectronic devices and generating pulses in Erbium fiber lasers at ultra
FTIR
FT-IR spectroscopy works by detecting the vibrations of chemical bonds when exposed to infrared radiation. The infrared region is divided into near, mid, and far infrared. FT-IR uses an interferometer which splits the infrared beam into two beams that travel different paths before recombining, allowing simultaneous measurement across the infrared spectrum. Components include an infrared source, beam splitter, stationary and moving mirrors, sample, and detector. FT-IR has advantages over dispersive IR including better sensitivity, resolution, and ability to measure the full spectrum quickly. Applications include analysis of materials, kinetics studies, and identification of compounds and chemical structures.
PhC_presentation
This document summarizes a lecture on photonic integrated circuits and photonic crystal multiplexer/demultiplexer devices. It introduces photonic crystals and defects that can localize light, such as point defects created by removing or altering a pillar, and line defects created by removing rows of pillars. These defects can act as resonant cavities or waveguides. The document then describes designing two wavelength multiplexer/demultiplexer devices using circular pillar photonic crystals with defects of different radii to filter wavelengths of 1310nm and 1550nm into separate output channels with low reflectivity and cross talk.
Femtosecond Machining
This presentation was made as a seminar requirement by Deepak Rajput at the University of Tennessee Space Institute, Tullahoma, Tennessee, USA in spring 2010.
Please visit http://drajput.com.
WORKING PRINCIPLE OF SEM.pptx
The document discusses the working principle of scanning electron microscopy (SEM). It describes how SEM uses a focused beam of electrons to scan the surface of a sample to produce images. SEM provides higher resolution than light microscopes due to the much shorter wavelength of electrons. The document outlines the various components of an SEM, including the electron gun, electromagnetic lenses, detectors for secondary electrons and backscattered electrons, and how these are used to control magnification and resolution. It also discusses some imaging parameters and artifacts that can influence SEM results.
Sem mahfooz
This document provides an overview of the working principle of a scanning electron microscope (SEM). It discusses key components of an SEM like the electron gun, condenser lenses, scan coils, objective lens, and detectors. It explains how SEM produces high-resolution images by scanning a focused beam of electrons across a sample. Secondary electrons and backscattered electrons are generated from sample-electron interactions and detected to form images. Factors affecting resolution, magnification and other imaging modes are also summarized. Advantages of SEM like high resolution and versatility are mentioned along with disadvantages like high cost, vacuum requirements and sample preparation needs.
Microwave photonics main
This document provides a tutorial on microwave photonics techniques developed in recent years for photonic generation and processing of microwave signals. It reviews optical generation of microwave signals using techniques such as optical injection locking, optical phase-lock loops, external modulation, and dual-wavelength laser sources. It also discusses photonic processing of microwave signals, true-time delay beamforming, radio-over-fiber systems, and photonic analog-to-digital conversion. The document emphasizes recent microwave photonics systems architectures and challenges in practical system implementation.
Similar to Cheng, Warren_Final Poster (20)
Dario Scotto - Detecting and Imaging Magneto-Optically Trapped Rubidium-85 Io...
Dario Scotto - Detecting and Imaging Magneto-Optically Trapped Rubidium-85 Io...
Fiber lasers and optoelectronic devices based on few layers of graphene - Luc...
Fiber lasers and optoelectronic devices based on few layers of graphene - Luc...
Cheng, Warren_Final Poster
- 1. Fig. 1 – Raman Spectroscopy • TERS was not supported by results, but it still exists • Proved the necessity of TERS because: 1. ~5nm bundle was measured ~400nm using Far-field 2. D-band was indiscernible from noise after defect • RBM peak shift could indicate a shift in the orientation of the bundled CNTs or change in CNT band structure Spincoated and then baked CoMoCAT SWCNT onto glass slides Far-field (as in step 2) and near-field (using the setup of Fig. 4 with the tip constantly over the focal point) images of the manipulated SWCNT were taken • Work with a single CNT strand instead of bundle • Obtain data showcasing TERS enhancement • Develop new opto-electric devices using the SWCNT structural deformation relation to electronic structure • Far-field Raman Spectroscopy has low spatial resolution ~300nm – (due to diffraction limit of propagating light d = λ/2) Tip-Enhanced Raman Spectroscopy (TERS) can achieve a spatial resolution of less than 30nm • Raman Scattering is very weak compared to Rayleigh Sct. (~1 in 10 million photons in a scattering event are Raman!) • Manipulation of CNTs could cause loss in Raman intensity TERS increases the Raman Scattering response by a factor of 100 - 104 The Study of Tip-Induced Deformations in Single-Walled Carbon Nanotubes Using Tip-Enhanced Near-Field Raman Spectroscopy http://nanojapan.rice.edu This material is based upon work supported by the National Science Foundation under Grant No. OISE‐0530220. Warren Cheng1,2, Shota Kuwahara2, and Satoshi Kawata2 1.NanoJapan Program, Rice University and Columbia Laboratory for Unconventional Electronics, Department of Electrical Engineering, Columbia University, NYC, USA 2. Laboratory for Scientific Instrumentation and Engineering, Department of Applied Physics, Osaka University, Osaka, Japan CONCLUSION Raman Spectroscopy Elastic Rayleigh Scattering Monochromatic Excitation Source Before After Inelastic Raman Scattering Filter Diffraction Grating Detector Sample Molecules • Possess electronic and vibrational properties which are dependent on the CNTs’ chirality (detected with Raman spectroscopy) Significance Future Work 1 • Evanescent illumination decreases the spot size of the laser confining the illuminated region of the sample • High NA p-polarized component of the laser increases the electromagnetic field along the metallized tip • Propagating photons are captured and confined at the apex of the hovering conical silver coated silicon tip due to coupling with localized surface plasmon polaritons How does TERS work? G+ G- D RBM Fig. 2 - Active Phonon Modes in CNT Carbon Nanotubes (CNT) Acknowledgements I would like to sincerely thank Prof. J. Kono, Dr. C. Matherly, K. Packard, S. Phillips, and Prof. C. Stanton of NanoJapan 2010 for developing such an amazing program that enabled me to achieve this dream. Thanks to Prof. S. Kawata for giving me the opportunity to work at LaSIE, to Y. Okuno for his helpful lessons, to the members of LaSIE and to last but certainly not least Dr. S. Kuwahara for his endless patience and guidance for without whom I could not have accomplished such a project. Fig. 4 – TERS Schematic Fig. 3 – Deformations in CNT • Deformations alter the CNTs’ energy band structure thereby altering their characteristics • Shifts in the phonon modes result from these alterations 2 • Used an AFM-Raman System comprised of a SII AFM system and Nikon Optical Microscope • Far-field image of the SWCNT was taken by raster scanning the sample with the setup in Fig. 4 but with the tip and evanescent mask removed Using a silicon Dynamic Force Microscopy (DFM) tip, a ~430 nm horizontal defect was introducedFig. 5 – AFM Image of Tip-Induced Deformation in CNT BEFORE AFTER 3 Process Raman Spectrometer Beam Profile (High NA) Evanescent Mask Expander Objective Lens (60x, NA = 1.4) Beam Splitter Near Field Probe (Silver Coated AFM Tip) Sample Longpass Filter Raman Signal Confined Field Focus Spot (~300nm) Diode Pumped Laser 532nm,10mW Expanded Laser Beam Carbon Nanotube Mirror G+ G- D RBM Fig. 2 – Raman Spectrum of CNT 1. Mono. Source Excites Sample 2. Molecules Vibrate & Scatters Light 3. Rayleigh Removed 4. Raman Spectra Detected METHOD 4 Before AFMRaman Manipulation AfterManipulation Raman AFM Intensity Profile at Manipulation Point CNT manipulation could not be discerned from TERS Image Raman SpectrumNear-field TERS Image 1μm Manipulation region was about 5 nm wide - determined with DFM Indicates a bundled structure containing 4 or 5 SWCNT Raman Spectra At Manipulation Point ΔG+ = 1.7 cm-1 ΔG- = 1.3 cm-1 ΔD = N/A (Low SNR) ΔRBM = 8 cm-1 Peak Shift Far-field Bundle Width~400nm RBM G+ G- D Intensity Decreases Raman at brightest point Raman Image Centered at G+ 1584 cm-1 Raman Image Centered at G+ 1586 cm-1 Manipulated SWCNT Bundle AFM 1 2 3 Measurement Taken Within RESULTSBACKGROUND Z. Liu, et. al., Chem. Comm.2009, 6902 (2009).