This document describes an experiment to build a pulsed fiber laser using erbium-doped fiber and the Kerr effect. The researchers were able to generate ≤400ps pulses within a 12 meter ring cavity at a peak spacing of about 60 ns. They believe this places the pulses in either the soliton or stretched pulse regime. The laser utilizes an artificial saturable absorber composed of polarizing elements to generate pulses in the 1550 nm spectrum through passive mode-locking via the Kerr effect and self-phase and self-amplitude modulation.
This document summarizes the use of graphene as a saturable absorber for mode-locked fiber lasers. It describes an experiment using a graphene saturable absorber in an erbium-doped fiber laser cavity. Soliton mode-locking was achieved with a threshold pump power of 60 mW. Optical spectra showed a 3dB bandwidth of 11.6 nm indicating soliton operation. Pulse characterization showed a repetition rate of 22.47 MHz with 62.2 pJ pulse energy and stable operation over 60 minutes. Radio frequency analysis verified stable mode-locking without Q-switching instabilities.
This document discusses frequency combs generated by stabilized femtosecond lasers. It begins by introducing frequency combs and their applications. It then describes how mode-locked lasers work and the two main techniques for mode-locking: active and passive. Passive mode-locking uses a saturable absorber to generate ultrashort pulses down to the femtosecond scale. The document explains that a frequency comb consists of equally spaced frequencies determined by the laser's repetition rate. It discusses how measuring both the repetition rate and carrier-envelope offset frequency allows full characterization of the comb frequencies.
This document discusses fiber optic communication and sensor systems. It begins with an introduction to fiber optics and covers topics like multichannel systems, optical switching and networks, all-optical time-division multiplexing technology, and optical fiber sensor technology. It then discusses key concepts in fiber optic communication like bandwidth, signal to noise ratio, transmission media alternatives to fiber optics, advantages of optical communication over satellite communication, wavelength-division multiplexing, numerical aperture, dispersion, and the tradeoff between high launching efficiency and reduced dispersion in optical fiber design.
Polarization mode dispersion (PMD) is a form of dispersion in optical fibers where the two polarization states of light travel at slightly different velocities, causing the optical signal to spread randomly. PMD occurs due to imperfections and asymmetries in the glass fiber core that introduce small refractive index variations between the two polarization states, known as birefringence. Low levels of PMD cause no distortion or bit errors in the digital signal, while high PMD can disperse the light wave enough to significantly distort the digital signal and cause multiple transmission errors. PMD is measured statistically along the fiber as the amount of dispersion between the two polarization states can vary randomly at different points.
The document compares three-level and four-level laser systems. Three-level lasers require pumping more than half the atoms to the upper level, resulting in high power needs and pulsed output. Four-level lasers move atoms to a long-lived metastable third level, allowing continuous operation with lower pumping rates. Examples given are ruby laser for three-level and He-Ne and Nd:YAG lasers for four-level. Four-level lasers provide advantages including lower lasing threshold, continuous output, and ability for continuous operation.
The document summarizes research on controlling the optical frequency variation of a 10GHz asynchronous harmonic mode-locked fiber soliton laser through continuous wave (CW) laser injection. Specifically:
1) The optical frequency variation of the mode-locked laser was measured to be around 5.47GHz without injection but was reduced to 0.95GHz, over a 5x reduction, with 10μW of CW injection while maintaining stable asynchronous mode-locking.
2) Higher CW injection levels above 10μW gradually degraded the signal-to-noise ratio of the mode-locked laser as the CW laser linewidth was wider than the individual optical frequency components.
3) The results demonstrate that CW injection can effectively suppress optical frequency
An Optical Time Domain Reflectometer (OTDR) injects optical pulses into fiber optic cables and measures the light that is scattered or reflected back to characterize the cable. It can measure the distance, loss, and other properties of fusion splices, connectors, bends, and other components in the cable. An OTDR is used to test the integrity of fiber optic cables and diagnose problems.
This document summarizes the use of graphene as a saturable absorber for mode-locked fiber lasers. It describes an experiment using a graphene saturable absorber in an erbium-doped fiber laser cavity. Soliton mode-locking was achieved with a threshold pump power of 60 mW. Optical spectra showed a 3dB bandwidth of 11.6 nm indicating soliton operation. Pulse characterization showed a repetition rate of 22.47 MHz with 62.2 pJ pulse energy and stable operation over 60 minutes. Radio frequency analysis verified stable mode-locking without Q-switching instabilities.
This document discusses frequency combs generated by stabilized femtosecond lasers. It begins by introducing frequency combs and their applications. It then describes how mode-locked lasers work and the two main techniques for mode-locking: active and passive. Passive mode-locking uses a saturable absorber to generate ultrashort pulses down to the femtosecond scale. The document explains that a frequency comb consists of equally spaced frequencies determined by the laser's repetition rate. It discusses how measuring both the repetition rate and carrier-envelope offset frequency allows full characterization of the comb frequencies.
This document discusses fiber optic communication and sensor systems. It begins with an introduction to fiber optics and covers topics like multichannel systems, optical switching and networks, all-optical time-division multiplexing technology, and optical fiber sensor technology. It then discusses key concepts in fiber optic communication like bandwidth, signal to noise ratio, transmission media alternatives to fiber optics, advantages of optical communication over satellite communication, wavelength-division multiplexing, numerical aperture, dispersion, and the tradeoff between high launching efficiency and reduced dispersion in optical fiber design.
Polarization mode dispersion (PMD) is a form of dispersion in optical fibers where the two polarization states of light travel at slightly different velocities, causing the optical signal to spread randomly. PMD occurs due to imperfections and asymmetries in the glass fiber core that introduce small refractive index variations between the two polarization states, known as birefringence. Low levels of PMD cause no distortion or bit errors in the digital signal, while high PMD can disperse the light wave enough to significantly distort the digital signal and cause multiple transmission errors. PMD is measured statistically along the fiber as the amount of dispersion between the two polarization states can vary randomly at different points.
The document compares three-level and four-level laser systems. Three-level lasers require pumping more than half the atoms to the upper level, resulting in high power needs and pulsed output. Four-level lasers move atoms to a long-lived metastable third level, allowing continuous operation with lower pumping rates. Examples given are ruby laser for three-level and He-Ne and Nd:YAG lasers for four-level. Four-level lasers provide advantages including lower lasing threshold, continuous output, and ability for continuous operation.
The document summarizes research on controlling the optical frequency variation of a 10GHz asynchronous harmonic mode-locked fiber soliton laser through continuous wave (CW) laser injection. Specifically:
1) The optical frequency variation of the mode-locked laser was measured to be around 5.47GHz without injection but was reduced to 0.95GHz, over a 5x reduction, with 10μW of CW injection while maintaining stable asynchronous mode-locking.
2) Higher CW injection levels above 10μW gradually degraded the signal-to-noise ratio of the mode-locked laser as the CW laser linewidth was wider than the individual optical frequency components.
3) The results demonstrate that CW injection can effectively suppress optical frequency
An Optical Time Domain Reflectometer (OTDR) injects optical pulses into fiber optic cables and measures the light that is scattered or reflected back to characterize the cable. It can measure the distance, loss, and other properties of fusion splices, connectors, bends, and other components in the cable. An OTDR is used to test the integrity of fiber optic cables and diagnose problems.
IRJET- Regeneration Analysis using Erbium Doped Fiber AmplifierIRJET Journal
This document summarizes a research paper that analyzes regeneration using erbium-doped fiber amplifiers. It begins with an abstract that outlines the goal of realizing an all-optical 3R regenerator for high-speed optical networks. It then discusses various components used in the system, including erbium-doped fiber amplifiers, semiconductor optical amplifiers, and fiber Bragg gratings. Simulation results are presented to evaluate the performance of the regenerator design for different parameters. The conclusions indicate that compensation techniques are needed to achieve high quality factors for transmission links operating at data rates of 40Gb/s and above.
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
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 :)
This report discusses the frequency response of a directly modulated laser. It describes how a carrier generator was used to create 298 channels with 25 MHz separations from 50 MHz as input to a laser diode. The laser's frequency response was then displayed using an RF spectrum analyzer. Nonlinearities in the laser were observed at higher amplitudes of the carrier generator input, changing the frequency response from a flat magnitude up to 2 GHz to one with kinks. Components of the simulation like the carrier generator, RFSA, laser and OSA are also outlined.
This document summarizes a student project on laser modulation response using Optiwave simulation software. The project involves:
1. Generating a pseudorandom bit sequence to drive a laser, producing an optical output.
2. Using a photodiode to convert the optical signal back to electrical, introducing harmonics.
3. Applying a Bessel filter to reduce harmonics and obtain the desired output signal quality in terms of eye height, Q-factor and bit error rate.
The document discusses laser modulation types, components used like the pseudorandom sequence generator, photodiode and Bessel filter, and observations on the laser's optical output response to modulation.
01 a review of the polarization nulling technique for monitoring optical-sign...waddah alkhulidy
This document reviews the polarization-nulling technique for monitoring optical-signal-to-noise ratio (OSNR) in dynamic wavelength-division multiplexing (WDM) networks. It describes how the technique utilizes different polarization properties of optical signals and noise to measure OSNR. However, its performance can be affected by factors like polarization-mode dispersion, nonlinear birefringence, and polarization-dependent loss in the transmission link. The document analyzes these effects and introduces techniques to overcome problems and accurately measure OSNR even with large differential group delays or nonlinear birefringence. It also evaluates the technique's performance in different fiber link experiments.
This document discusses different modes of laser operation, including continuous wave (CW), pulsed, Q-switching, and mode-locking modes. It describes free running laser pulse mode, where the pulse width is controlled by the pumping pulse. For Q-switching, a device is inserted to make the quality factor vary between minimum and maximum, producing very short, high power pulses. Mode-locking synchronizes multiple cavity modes, resulting in ultrashort intensity spikes spaced by the cavity roundtrip time.
An optical modulator is a device that modulates or varies the amplitude of an optical signal in a controlled manner. It generates desired intensity and color in light by changing optical parameters like transmission, refractive index, or reflection according to an input signal. Common types of optical modulators include electroabsorption modulators, electro-optic modulators, acousto-optic modulators, and Mach-Zehnder interferometric modulators. Optical modulators are important for applications like optical communication systems.
Wavelength converters are devices that convert data from one incoming wavelength to another wavelength. They enable optical channels to be relocated and are achieved using nonlinear optical effects. Wavelength converters are useful in WDM networks for three reasons: 1) data may enter the network at an unsuitable wavelength, 2) converters may improve wavelength utilization on network links, and 3) converters may be needed when networks managed by different entities do not coordinate wavelength allocation. Common types of wavelength converters include optoelectronic, optical gating using cross-gain modulation, and four-wave mixing approaches.
The document discusses nanosecond lasers, which produce optical pulses with durations measured in nanoseconds. It describes how nanosecond pulses are generated using techniques like Q-switching and gain switching that produce high intensity pulses. Nanosecond lasers have applications in fields like materials processing, distance measurement, remote sensing, and more due to their ability to deliver high pulse energies over short timescales.
This document discusses coherence and optical fibers. It defines temporal and spatial coherence, which refer to the ability of waves to interfere with themselves or other waves at different times or positions, respectively. Coherence is necessary for interference. Optical fibers transmit light via total internal reflection within a core surrounded by cladding. Fibers can be single-mode or multi-mode depending on the number of propagation modes supported. Numerical aperture specifies the range of angles at which light can enter and propagate within the fiber.
This document discusses different types of all-optical switches that use Bragg gratings and the Kerr effect. It describes a nonlinear directional coupler loaded with a Bragg reflector that can act as an all-optical switch, directing light to different ports based on the presence of a control light. It also discusses an optical fiber grating coupler all-optical switch and a periodically curved nonlinear waveguide all-optical switch, noting advantages like lower power requirements and sharper switching widths.
Q-switching is a technique used to produce high-power laser pulses. It involves preventing the laser from oscillating to allow the population inversion in the lasing medium to build up to a high level. Then, by suddenly allowing oscillation, all the stored energy is emitted in a single giant pulse with peak power much higher than during normal operation. The pulse duration is typically 10-7 to 10-8 seconds. Q-switching provides a means to drastically increase the laser power output through stimulated emission of a very large number of atoms in the active medium.
Fiber Bragg gratings are filters built into the core of optical fibers that reflect specific wavelengths of light and transmit others. They can be used as inline filters or wavelength-specific reflectors to improve optical signal quality. The document discusses several types of FBGs: uniform FBGs with consistent grating periods; chirped FBGs with varying periods that act as dispersion compensators; blazed FBGs with tilted grating planes that reflect light out of the fiber; phase-shifted FBGs with periodic index changes that create narrow transmission windows; and long-period FBGs that couple light into cladding modes, removing resonant wavelengths from the system. Each FBG type has distinct features and applications in optical communications, sensing, and laser
Effective Laser Decapsulation Employing the Digital ICO Laser and HAZ-Methodo...Laser-Lance Fordham
The document provides a tutorial on effectively using a Digital ICO laser for semiconductor decapsulation. It discusses how to optimize laser parameters like pulse energy, pulse density, pulse profile, speed, and fill-spacing to control the heat affected zone and achieve close decapsulation without damage. The laser's ability to customize pulse profiles allows balancing ablation rate and heat. Setting proper focus based on part thickness is also important to maintain uniform ablation depth. Examples show applying the techniques to challenging parts.
This document discusses different types of optical filters used in optical communication systems. It describes four common optical filters: grating filters, arrayed waveguide grating (AWG) filters, fiber Bragg grating filters, and Fabry-Perot filters. Grating filters use diffraction gratings to spatially separate wavelengths. AWG filters use arrays of waveguides as interferometers. Fiber Bragg gratings act as reflectors for specific wavelengths due to periodic refractive index variations. Fabry-Perot filters use an optical cavity between two mirrors to selectively transmit wavelengths through interference.
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.
The document describes experiments conducted using fiber optic equipment kits to study various fiber optic components. In experiment 1, a laser characterization kit is used to characterize lasers and measure properties of fused biconical taper couplers, isolators, circulators, and Bragg gratings. Measurements are taken of input and output power at various ports. In experiment 2, a fiber optic communication kit is used to characterize LED and laser diode sources, measure attenuation over different length fiber spools, and determine bandwidth. Experiment 3 uses a laser kit to measure output power from a laser source, construct a band limiting filter, and measure input/output power of feedback couplers and a variable attenuator.
This document describes a new method for controlling the bandwidth of high-energy, few-optical-cycle laser pulses tunable from the visible to near-infrared spectrum. The method uses femtosecond laser pulses that are positively chirped using a chirped-pulse amplifier and then sent through a hollow core fiber filled with neon gas. Self-phase modulation in the neon gas results in spectral broadening, followed by a pair of chirped mirrors that compensate for dispersion. This allows direct tuning of the output pulse bandwidth by varying the chirping of input pulses and neon gas pressure. Output pulse energies as high as 0.6 mJ were achieved, over two orders of magnitude higher than other existing techniques,
The researchers built a low rotation sensing interferometric fiber optic gyroscope (I-FOG) using an amplified open loop Sagnac interferometer. The device was able to detect rotations as low as 1 degree per minute. Sensitivity was achieved using a piezoelectric modulator paired with a lock-in amplifier to reduce noise and amplify the signal. While the device could detect rotations of 1 degree per minute, reliable measurements of the Earth's rotation of 0.25 degrees per minute were not possible due to limitations of the calibration equipment. Future work to improve sensitivity includes reducing noise and using more reliable components.
IRJET- Regeneration Analysis using Erbium Doped Fiber AmplifierIRJET Journal
This document summarizes a research paper that analyzes regeneration using erbium-doped fiber amplifiers. It begins with an abstract that outlines the goal of realizing an all-optical 3R regenerator for high-speed optical networks. It then discusses various components used in the system, including erbium-doped fiber amplifiers, semiconductor optical amplifiers, and fiber Bragg gratings. Simulation results are presented to evaluate the performance of the regenerator design for different parameters. The conclusions indicate that compensation techniques are needed to achieve high quality factors for transmission links operating at data rates of 40Gb/s and above.
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
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 :)
This report discusses the frequency response of a directly modulated laser. It describes how a carrier generator was used to create 298 channels with 25 MHz separations from 50 MHz as input to a laser diode. The laser's frequency response was then displayed using an RF spectrum analyzer. Nonlinearities in the laser were observed at higher amplitudes of the carrier generator input, changing the frequency response from a flat magnitude up to 2 GHz to one with kinks. Components of the simulation like the carrier generator, RFSA, laser and OSA are also outlined.
This document summarizes a student project on laser modulation response using Optiwave simulation software. The project involves:
1. Generating a pseudorandom bit sequence to drive a laser, producing an optical output.
2. Using a photodiode to convert the optical signal back to electrical, introducing harmonics.
3. Applying a Bessel filter to reduce harmonics and obtain the desired output signal quality in terms of eye height, Q-factor and bit error rate.
The document discusses laser modulation types, components used like the pseudorandom sequence generator, photodiode and Bessel filter, and observations on the laser's optical output response to modulation.
01 a review of the polarization nulling technique for monitoring optical-sign...waddah alkhulidy
This document reviews the polarization-nulling technique for monitoring optical-signal-to-noise ratio (OSNR) in dynamic wavelength-division multiplexing (WDM) networks. It describes how the technique utilizes different polarization properties of optical signals and noise to measure OSNR. However, its performance can be affected by factors like polarization-mode dispersion, nonlinear birefringence, and polarization-dependent loss in the transmission link. The document analyzes these effects and introduces techniques to overcome problems and accurately measure OSNR even with large differential group delays or nonlinear birefringence. It also evaluates the technique's performance in different fiber link experiments.
This document discusses different modes of laser operation, including continuous wave (CW), pulsed, Q-switching, and mode-locking modes. It describes free running laser pulse mode, where the pulse width is controlled by the pumping pulse. For Q-switching, a device is inserted to make the quality factor vary between minimum and maximum, producing very short, high power pulses. Mode-locking synchronizes multiple cavity modes, resulting in ultrashort intensity spikes spaced by the cavity roundtrip time.
An optical modulator is a device that modulates or varies the amplitude of an optical signal in a controlled manner. It generates desired intensity and color in light by changing optical parameters like transmission, refractive index, or reflection according to an input signal. Common types of optical modulators include electroabsorption modulators, electro-optic modulators, acousto-optic modulators, and Mach-Zehnder interferometric modulators. Optical modulators are important for applications like optical communication systems.
Wavelength converters are devices that convert data from one incoming wavelength to another wavelength. They enable optical channels to be relocated and are achieved using nonlinear optical effects. Wavelength converters are useful in WDM networks for three reasons: 1) data may enter the network at an unsuitable wavelength, 2) converters may improve wavelength utilization on network links, and 3) converters may be needed when networks managed by different entities do not coordinate wavelength allocation. Common types of wavelength converters include optoelectronic, optical gating using cross-gain modulation, and four-wave mixing approaches.
The document discusses nanosecond lasers, which produce optical pulses with durations measured in nanoseconds. It describes how nanosecond pulses are generated using techniques like Q-switching and gain switching that produce high intensity pulses. Nanosecond lasers have applications in fields like materials processing, distance measurement, remote sensing, and more due to their ability to deliver high pulse energies over short timescales.
This document discusses coherence and optical fibers. It defines temporal and spatial coherence, which refer to the ability of waves to interfere with themselves or other waves at different times or positions, respectively. Coherence is necessary for interference. Optical fibers transmit light via total internal reflection within a core surrounded by cladding. Fibers can be single-mode or multi-mode depending on the number of propagation modes supported. Numerical aperture specifies the range of angles at which light can enter and propagate within the fiber.
This document discusses different types of all-optical switches that use Bragg gratings and the Kerr effect. It describes a nonlinear directional coupler loaded with a Bragg reflector that can act as an all-optical switch, directing light to different ports based on the presence of a control light. It also discusses an optical fiber grating coupler all-optical switch and a periodically curved nonlinear waveguide all-optical switch, noting advantages like lower power requirements and sharper switching widths.
Q-switching is a technique used to produce high-power laser pulses. It involves preventing the laser from oscillating to allow the population inversion in the lasing medium to build up to a high level. Then, by suddenly allowing oscillation, all the stored energy is emitted in a single giant pulse with peak power much higher than during normal operation. The pulse duration is typically 10-7 to 10-8 seconds. Q-switching provides a means to drastically increase the laser power output through stimulated emission of a very large number of atoms in the active medium.
Fiber Bragg gratings are filters built into the core of optical fibers that reflect specific wavelengths of light and transmit others. They can be used as inline filters or wavelength-specific reflectors to improve optical signal quality. The document discusses several types of FBGs: uniform FBGs with consistent grating periods; chirped FBGs with varying periods that act as dispersion compensators; blazed FBGs with tilted grating planes that reflect light out of the fiber; phase-shifted FBGs with periodic index changes that create narrow transmission windows; and long-period FBGs that couple light into cladding modes, removing resonant wavelengths from the system. Each FBG type has distinct features and applications in optical communications, sensing, and laser
Effective Laser Decapsulation Employing the Digital ICO Laser and HAZ-Methodo...Laser-Lance Fordham
The document provides a tutorial on effectively using a Digital ICO laser for semiconductor decapsulation. It discusses how to optimize laser parameters like pulse energy, pulse density, pulse profile, speed, and fill-spacing to control the heat affected zone and achieve close decapsulation without damage. The laser's ability to customize pulse profiles allows balancing ablation rate and heat. Setting proper focus based on part thickness is also important to maintain uniform ablation depth. Examples show applying the techniques to challenging parts.
This document discusses different types of optical filters used in optical communication systems. It describes four common optical filters: grating filters, arrayed waveguide grating (AWG) filters, fiber Bragg grating filters, and Fabry-Perot filters. Grating filters use diffraction gratings to spatially separate wavelengths. AWG filters use arrays of waveguides as interferometers. Fiber Bragg gratings act as reflectors for specific wavelengths due to periodic refractive index variations. Fabry-Perot filters use an optical cavity between two mirrors to selectively transmit wavelengths through interference.
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.
The document describes experiments conducted using fiber optic equipment kits to study various fiber optic components. In experiment 1, a laser characterization kit is used to characterize lasers and measure properties of fused biconical taper couplers, isolators, circulators, and Bragg gratings. Measurements are taken of input and output power at various ports. In experiment 2, a fiber optic communication kit is used to characterize LED and laser diode sources, measure attenuation over different length fiber spools, and determine bandwidth. Experiment 3 uses a laser kit to measure output power from a laser source, construct a band limiting filter, and measure input/output power of feedback couplers and a variable attenuator.
This document describes a new method for controlling the bandwidth of high-energy, few-optical-cycle laser pulses tunable from the visible to near-infrared spectrum. The method uses femtosecond laser pulses that are positively chirped using a chirped-pulse amplifier and then sent through a hollow core fiber filled with neon gas. Self-phase modulation in the neon gas results in spectral broadening, followed by a pair of chirped mirrors that compensate for dispersion. This allows direct tuning of the output pulse bandwidth by varying the chirping of input pulses and neon gas pressure. Output pulse energies as high as 0.6 mJ were achieved, over two orders of magnitude higher than other existing techniques,
The researchers built a low rotation sensing interferometric fiber optic gyroscope (I-FOG) using an amplified open loop Sagnac interferometer. The device was able to detect rotations as low as 1 degree per minute. Sensitivity was achieved using a piezoelectric modulator paired with a lock-in amplifier to reduce noise and amplify the signal. While the device could detect rotations of 1 degree per minute, reliable measurements of the Earth's rotation of 0.25 degrees per minute were not possible due to limitations of the calibration equipment. Future work to improve sensitivity includes reducing noise and using more reliable components.
Fluorescence spectroscopy analyzes fluorescence from a sample using light, usually ultraviolet light, to excite electrons in molecules of certain compounds causing them to emit light of a lower energy. Molecules have various electronic and vibrational energy levels, and fluorescence spectroscopy examines electronic state transitions. A photon excites a molecule to a higher vibrational state, which then loses energy and drops to the lowest excited state, emitting a photon of different energy upon returning to the ground state.
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.
INFRARED SPECTROSCOPY to find the functional groupssusera34ec2
This document provides an overview of infrared spectroscopy. It discusses the principle, theory, instrumentation, sample preparation, qualitative and quantitative analysis, uses, applications, and limitations. Infrared spectroscopy analyzes the infrared region of the electromagnetic spectrum to identify functional groups and compounds. The main instruments are dispersive spectrometers and Fourier transform infrared spectrometers. Infrared spectroscopy is widely used in research and industry for structure elucidation, compound identification, and determining organic and inorganic materials.
IOSR Journal of Applied Physics (IOSR-JAP) is an open access international journal that provides rapid publication (within a month) of articles in all areas of physics and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in applied physics. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
This document discusses using trapped picosecond soliton pulses in microring resonators to generate entangled photon pairs for quantum keys. Simulations show soliton pulses with peak powers of 500-550 mW can be trapped within resonator frequencies of 3.52 GHz. This generates a 25 picosecond temporal soliton pulse that can be used to produce entangled photon pairs. The photons are then transmitted using a wireless router system to securely communicate information over an optical network. The microring resonators balance dispersion and nonlinearity to localize the soliton pulses for generating the entangled photons needed for quantum cryptography.
This document provides an overview of lasers and laser gain media. It discusses the basic laser (oscillator) concept and how optical feedback allows for stimulated emission and light amplification. A variety of laser gain media are described, including gases (HeNe, CO2, excimer), dyes, and solid-state materials (ruby, Nd:YAG, Yb:YAG). The energy levels and pumping mechanisms that produce population inversion in three-level and four-level laser systems are also summarized.
This document provides an overview of ultraviolet-visible spectroscopy. It defines UV-VIS spectroscopy and discusses the principle, instrumentation, and applications. Key points include:
1) UV-VIS spectroscopy measures the attenuation of light passing through a sample, allowing detection of electronic transitions in molecules from absorption measurements.
2) The absorption spectrum provides information on maximum wavelength of absorption and intensity. Instrumentation includes a light source, monochromator, sample holder, and detector.
3) Applications include qualitative and quantitative analysis of compounds, detection of functional groups and impurities, and determination of concentration. UV-VIS spectroscopy is useful for studying kinetics, tautomers, and inorganic compounds.
There are three main types of laser gain media: gases, liquids, and solids. Gases like CO2 have narrow wavelength gain, while liquids like dyes have broad gain. Solid state lasers like Nd:YAG can have either narrow or broad gain depending on the material. All gain media require pumping to receive energy, which can be optical pumping using lamps or flashlights, or electrical pumping using gas discharges. Q-switching is a technique to produce high power pulses using a Pockels cell to prevent lasing until a population inversion is fully inverted.
The document provides an overview of UV-visible spectroscopy. It discusses how UV-visible spectroscopy works by measuring absorption or emission of electromagnetic radiation by molecules. It describes the instrumentation used in UV-visible spectroscopy including light sources, sample handling using cuvettes, and detectors. It also covers concepts like chromophores, transitions between molecular orbitals, and selection rules. Applications discussed include analysis of functional groups, determination of structure and configuration of compounds.
This document summarizes the characterization and optimization of a thermal lensing compensated Ti:Sapphire femtosecond laser system operating at 1-kHz repetition rate using frequency resolved optical gating (FROG). The laser system is optimized to produce 4.0 mJ pulses at 30 fs duration. Thermal lensing in the amplifier crystals is compensated using convex mirrors and Peltier cooling. Single-shot SHG-FROG is used to characterize the pulses in both the frequency and time domains. Optimization of the grating compressor is performed to minimize pulse duration, achieving 30 fs pulses at zero grating detuning.
This document provides an overview of ultraviolet-visible (UV-Vis) spectroscopy. It defines UV-Vis spectroscopy as the measurement of light absorption by a sample after it passes through or is reflected from the sample. The document outlines key components of UV-Vis spectroscopy including the absorption spectrum, types of electronic transitions that can occur, Beer's and Lambert's laws describing the relationship between absorbance and concentration, instrumentation components, and applications such as qualitative and quantitative analysis. Effects of chromophores, solvents, and auxochromes on absorption spectra are also discussed.
It is an analytical technique uselful for detection of functional groups present in particular molecules and compounds.
It is highly applicable in pharmaceutical and chemical engineering.
This document summarizes research on using microring resonators (MRRs) to trap optical solitons and generate entangled photon pairs for quantum key distribution. Simulations show ultra-short soliton pulses can be trapped within MRRs at specific frequencies and time durations. Polarization-entangled photon pairs are generated from the solitons and different pairs are encoded in different time slots. The entangled photons can be transmitted securely over a wireless network using a router system. The research demonstrates how MRRs can localize spatial and temporal solitons to generate quantum keys for optical communication security.
Infrared spectroscopy measures the bond vibrations in molecules to determine their functional groups. There are two main types of instruments - dispersive and Fourier transform infrared spectroscopy. Dispersive instruments use gratings to separate infrared frequencies, while FT-IR uses interferometers and Fourier transforms. Samples can be analyzed as solids, liquids in cells, or gases in gas cells. The infrared region is divided into functional group and fingerprint regions that are used for structure elucidation and identification of compounds, drugs, polymers, and more. Molecular vibrations occur as stretching and bending modes. Factors like hydrogen bonding, conjugation, and inductivity affect vibrational frequencies.
Pulse Shaping Of Tea Co2 Laser Using A Simple Plasma ShutterNoah Hurst
The document describes a simple plasma shutter for shaping the pulse of a TEA CO2 laser. The laser pulse normally consists of a sharp initial spike followed by a long nitrogen tail containing most of the energy. The plasma shutter uses a pinhole and focusing lens to generate plasma from the laser beam, truncating the pulse after the initial spike. This increases the average power by eliminating the low-power nitrogen tail. Experimental results showed the shutter could produce stable pulses as short as 30 ns by varying the pinhole position. A 60 ns clipped pulse matched the properties of the initial spike from the original pulse. The simple and inexpensive design effectively shaped the laser pulse without sacrificing energy or stability.
Infrared spectroscopy is a technique that uses infrared light to analyze chemical bonding and structure. It works by measuring the frequencies at which molecules vibrate and absorb infrared radiation. Modern infrared instruments use a Fourier transform method with an interferometer to produce an infrared spectrum that acts as a molecular "fingerprint". Infrared spectroscopy is useful for identifying unknown materials, determining molecular structure of organic and inorganic compounds, and studying molecular interactions.
All-Optical OFDM Generation for IEEE802.11a Based on Soliton Carriers Using M...University of Malaya (UM)
The optical carrier generation is the basic building block to implement all-optical
orthogonal frequency-division multiplexing (OFDM) transmission. One method to optically
generate single and multicarriers is to use the microring resonator (MRR). The MRRs can be
used as filter devices, where generation of high-frequency (GHz) soliton signals as single
and multicarriers can be performed using suitable system parameters. Here, the optical
soliton in a nonlinear fiber MRR system is analyzed, using a modified add/drop system
known as a Panda ring resonator connected to an add/drop system. In order to set up a
transmission system, i.e., IEEE802.11a, first, 64 uniform optical carriers were generated and
separated by a splitter and modulated; afterward, the spectra of the modulated optical
subcarriers are overlapped, which results one optical OFDM channel band. The quadrature
amplitude modulation (QAM) and 16-QAM are used for modulating the subcarriers. The
generated OFDM signal is multiplexed with a single-carrier soliton and transmitted through
the single-mode fiber (SMF). After photodetection, the radio frequency (RF) signal was
propagated. On the receiver side, the RF signal was optically modulated and processed.
The results show the generation of 64 multicarriers evenly spaced in the range from 54.09 to
55.01 GHz, where demodulation of these signals is performed, and the performance of the
system is analyzed.
This document provides an overview of UV spectroscopy. It discusses electronic transitions that occur in the UV region, including σ → σ*, n → σ*, n → π*, and π → π* transitions. Selection rules that determine observable transitions are also covered. The Beer-Lambert law relating absorbance to concentration is introduced. Instrumentation for UV spectroscopy including various light sources, monochromators, and detectors is described.
Similar to Mode-Locked Erbium Doped Pulse Fiber Laser Using the Kerr Effect (20)
2. The Kerr mode-locked pulsed fiber laser consists of multiple
components, as seen infigure 1, beginning with the 980 nm pump
laser. After the 980nm pump, one side of the wavelength division
multiplexer (WDM) has two inputs, one receives 980 nm allowing
it inthe ring as well as allowing 1550nm light to transmit through
the other, which closes the ring cavity. The other end is acommon
fiber that allows both wavelengths to pass through. The common
fiber from the WDMisconnected tothe Liekki Er-30-4/125 Erbium
doped active fiber, which acts as a gain medium. As the 1550 nm
beam travels through the gain medium, an additional WDM is
encountered, this time inreverse, to dump any remaining 980 nm
light and send solely 1550 nm beam into the optical isolator. The
beam that travels through the optical isolator becomes
unidirectional meaning the beam can only travel in one direction
within the cavity. An optical bench consisting of ahalf-wave plate,
polarizer and quarter-wave plate is located after the isolator
resulting in transmission of high intensity light while attenuating
low-intensity light. After the components within the optical bench,
pulses travel through a95/5 output coupler where 95% ofthe light
is sent back into the cavity through the 1550 nm fiber of the initial
WDM and 5% of the beam is output from the ring cavity. The 5%
signal output will then be sent to the photodetector forobservation
onthe oscilloscope and spectral analyzer.
PROCEDURE
Tobegin the project wehad to findthe components necessary
for the ring cavity, as described inthe set-up section. Once wehad
found the necessary components, we needed to connectorize and
accurately measure the length of each, so we could determine the
round trip distance of the ring cavity. The accurate length of the
cavity was essential todetermine theperiod ofthe pulses within the
cavity. Thenext step was to test our predictions of the period using
well-polished connections andaccurate lengths. Withallthe passive
components connected, the only component we varied in the
system was the erbium-doped fiber.
Initially, we placed a 0.5 meter and then a 1meter long Moritex
Er-112 fiber within ourring cavity to attempt to achieve the soliton
regime. Incorporating the 0.5 and 1-meter long erbium cable ledto
anunstable signal withself-pulsing results. The self-pulsing wesaw
with the Er-112 fiber hadto do with ahighconcentration of erbium
ions[5].This caused stimulated emissionofneighboring ionswithin
acluster, creating self-pulsing. Moreover, wereplaced the Moritex
Er-112 fiber with a 7.5 meter LIEKKI Er-30 (Absorption 30 +/- 3
dB) fiber containing lower concentration [6]. With the Er-30 fiber
placed within the ring cavity, we found very distinct pulses with
minimal noise. To confirm that we were inthe soliton regime, we
input additional various lengths ofSMF-28 fiber ranging from 2to 4
meters. The SMF-28 has an opposite dispersion of the erbium and
allows additional non-doped fiber to beincluded into our system to
manipulate the GVD.
We collected and compared data from two different sources.
The first was noting the voltage of the signal on the Tektronix
DPO7354 3.5 GHz oscilloscope, using a Thorlabs 1.2 GHz
photodetector. Using this technique, we were able to determine
peak power, period and pulse width. The other process of
measurement included using the Advantest Q8381A optical
spectrum analyzer, which was able to observe the power profile as
afunction of wavelength.
OPTICAL KERREFFECT
The optical Kerr effect pertains to a change in the index of
refraction when high intensity light is incident onthe material. This
is a result of the small order of the nonlinear index of refraction
(~10-20). Unless the intensity ishigh enough, the nonlinear change
in index is negligible. We see that the new index of refraction is
represented by
𝑛 = 𝑛0 + 𝑛2 𝐼. (1.3)
Where n0 isthe linear index, n2 isthe non-linear index and Iisthe
intensity. We see that if the intensity is low, the factor of the non-
linear index isnot going to change the linear index. This change in
index is what gives rise to the self-phase modulation inthe system
[4].
A. SELF-PHASE MODULATION
Self-phase modulation isaresult of the Kerr effect inthe fiber. In
oursystem, light travels around the cavityinanelliptically polarized
state. The major and minor axis of the ellipse have different
magnitudes, thus have a different effect on the non-linear index of
refraction. These different effects onthe index of refraction lead to
each axis of the ellipsetravelling atdifferent speeds within the fiber.
Subsequently, this causes the ellipticity of the light to rotate as it
propagates through the loopof thesystem. Thiscomponent aswell
as the self-amplitude modulation of the polarizing elements led to
Kerr modelocking.
B. SELF-AMPLITUDE MODULATION
As the elliptically polarized light is incident upon the λ/2 wave
plate, the axis of the ellipse begins to rotate. If the λ/2 wave plate is
oriented as suchthat the major axis ofthe ellipseisaligned with the
polarizer, the polarizer allows the higher intensity light to pass
through as well as blocking out orthogonal, lower intensity light.
This attenuation of lower modes iswhat leads to mode locking the
light within the cavity. The combination of the optical Kerr effect
that leads to the self-phase modulation and the self-amplitude
modulation are what lead to mode locking short, high amplitude
pulses.
COMPARISON OFREGIMES
Once pulses were observed on the oscilloscope, we referred to
the spectrum analyzer to check which regime our pulses were in.
There are two regimes that pulses can be within, soliton or
stretched-pulse. These are represented by the power of each pulse
as a function of wavelength. Solitons occur when apulse resulting
from the ratio of passive fiber to active fiber within the ring cavity
has azero ornegative dispersion. Unique characteristics of solitons
consist of self-stabilizing and maintaining their spectral and
temporal shape inthe cavity due to the cancellation of the GVDand
SPM [3]. Solitons are quantized and expect a step-like feature as a
function of pump power.
In comparison, stretched-pulses occur when the overall
dispersion is positive. As a result there is a large difference of the
SPM and GVD. This causes the pulses being periodically stretched
and recompressed ineach resonator round-trip [2].Stretched pulse
regime has a linear trend as a function of pump power, as seen in
figure 2.
3. Fig 2. Linearcharacteristic of the stretched pulse regime.
RESULTS
Before webegan taking measurements, weobserved the power
out ofthe pumpand compared itto the power leaving the output
coupler. Wefound that there was about 450 mWleaving the pump
and measured about 2.3 mWof 1550 nm light leaving our5%
signal. Inorder to get the total power within the ring, wemultiply
by 20to get about 46mW. Wecansee that there isadecent
amount of losswithin the ring cavity.
Fig 3. Pulses with a period of about 60 ns displayed on the
oscilloscope.
Wewere able to produce modelocked pulsing within our cavity,
with aperiod closeto the round trip time of the cavity. These values
align with the theory wehad predicted. In our 12m loop, assuming
5ns/m for the light inthe cavity wewere able to get pulsing with a
period of about 60 ns, which can be seen in figure 3. Another
parameter wewere interested inwas the widthof the pulses within
the cavity. We measured an average pulse width of ≤400 ps. The
reason wereport that as less than orequal to is wewere limited by
the rate of collection of the different devices. The photodetector ran
at a frequency of 1.2 GHz and the o-scope was limited to 3.5 GHz,
corresponding to tenths of nanoseconds.
Fig4.Imagestaken from the spectrometer displaying the spectra
of the stretched pulse(left) and solitonregime (right).
Another aspect of the pulses we were observing was the
difference between the stretched pulse and the soliton regime. We
believe that wewere able toobserve bothregimes. Thetrouble with
calculating these different regimes was wewere unable to comeup
with an exact value forthe GVD of the erbium doped fiber. Wehad
found some values within the literature, which were inconclusive.
We also contacted the manufacturer and they were unsure of the
value. First, we estimated a negative overall dispersion, i.e. the
stretched pulse regime. Through the addition of enough passive
fiber, the system crossed over to the soliton regime. In figure 3, the
differences inspectra are what we believe to be the two different
regimes.
We can see in the left image of figure 4, the stretched pulse
regime, where we have one peak with no side modes. In the right
figure weseethat wehave some,however inconsistent, sidemodes.
These differences are what we believe are the two different
regimes.
Conclusion
The purpose of our project was to produce mode locked pulses,
in a fiber ring utilizing the optical Kerr effect. We were able to
produce pulses that were on the order of the round trip time with
the width on the order of what we expected. The other aspect we
were observing iswhat dispersion regime wewere in, the stretched
pulse orthe solitonregime. Ourresults are inconclusive, however it
appears we were able to obtain the soliton as well as the stretched
pulse regime. We believe we obtained both, however due to an
unknown value of GVD dispersion from the Er-30, we cannot be
certain.
In the future, multiple aspects of the experiment could be
improved. If various components were fusionspliced, as opposed to
connectorized that would improve the efficiency of the loop.
Additionally, by thermally and mechanically stabilizing the
components ofthe system, this couldimprove the stability. Further
improvements that couldbeexplored isincreasing thepump power
to the system, by coupling two pumps together and using an
improved oscilloscope to have more accurate results onthe order
offemtoseconds. Wecouldalso explore thedifferent concentrations
of the Erbium doped fiber to see if an increase in power with a
higher concentration couldproduce higher power pulses. Although
we achieved results that created very distinct pulses, we believe
better results could be produced using the techniques mentioned.
Overall, we established many skills such as fiber polishing
throughout this project and successfully mode-locked an Erbium
doped pulsefiber laser using the Kerr effect.
References
[1] N., Usechak G. "Mode Locking of Fiber Lasers at High Repetition Rates."
(n.d.): n. pag. University of Rochester, 2006. Web. 30 Aug. 2016.
[2] R. Paschotta. "Passive Mode Locking." Encyclopedia of Laser Physics and
Technology. RP Photonics Consulting GmbH, 2012. Web. 29 Aug. 2016.
[3] B. Boggs. "Mode-locked Erbium-Ytterbium Doped Fiber Laser." Mode-
locked Erbium-Ytterbium Doped Fiber Laser. University of Oregon,
Department of Physics, Advanced Projects Lab's Wiki, 6Sept. 2015. Web. 28
Aug. 2016.
[4] R. Paschotta. "Kerr Effect." Encyclopedia of Laser Physics and Technology.
RP Photonics Consulting GmbH, 2012. Web. 28 Aug. 2016.
[5] Moritex. "Standard PureCore™ Erbium Doped Optical Fibers." (2010): n.
pag. Moritex PureCore™ Erbium Doped Specialty Optical Fibers. Moritex, 1
Sept. 2016. Web.
[6] NLight. LIEKKI ®(n.d.): n. pag. LIEKKI. NLight. Web. 1 Sept. 2016.