Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"phase modulator"”.
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Terfenol based optical phase modulator and magnetometer
Two new fiber optic magnetostrictive phase modulators and magnetometers using the highly magnetostrictive rare-earth iron compound Tb<sub>x</sub>Dy<sub>l-x</sub>Fe₂ are investigated. They demonstrated to have a high sensitivity, dynamic range, minimum field detectability, and a better structural …
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Graphene Modulators for Silicon Photonic Optical Links
… encoded in light, relying on electro-optic modulators to convert the electrical data signal into the optical domain, and photodetectors to convert the optical signal back into the electrical domain. Power consumption can be reduced by using efficient and compact modulators and photodetectors …
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Phase manipulation for efficient radio frequency transmission
… design are considered. First, a wide-band phase modulator is introduced that uses a single current-steering digital to analog converter (DAC) structure and discrete clock prerotation. This topology takes advantage of specifications particular to outphasing architectures to reduce matching …
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Amplitude and phase modulation techniques for an asymmetric multi-level outphasing transmitter
… the power supply switching network and the phase modulator. Both are ubiquitous building blocks in modern RF transceivers, and both are especially critical in Asymmetric Multilevel Outphasing (AMO) systems. A design of the power supply network and control scheme is proposed for an …
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Analysis and IC Implement of Digitally Controlled Multi-Port DC -Dc Converters
… a multi-port single controller and (2) a digital phase modulator. These control techniques cannot be implemented in an analog controller. This shows that certain digital control techniques are suitable for specific functions that are not achievable or too expensive in analog. The proposed digital …
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High-order compensation of self-phase modulation in laser communication systems
Self-phase modulation (SPM) creates a power and fiber-length dependent spectral broadening that reduces signal-to-noise ratio in free-space laser communication systems which use a fiber to connect their transmitter's high-power optical amplifier to its telescope optics. The effects of SPM can be …
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Ultralow-noise modelocked lasers
… of a timing jitter eater, consisting of a phase modulator and dispersive fiber, show that.
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Nanophotonic visible light phased arrays
Previously demonstrated integrated optical phased arrays have primarily been implemented in silicon-based platforms and have therefore been limited to operation at infrared wavelengths, where silicon provides low-loss transmission. Developing integrated optical phased arrays for visible wavelengths …
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Phase stabilization of laser beams in a cold atom accelerometer
… limited by the stability of the relative laser phase of the two interrogation laser beams, which is adversely affected by vibrations and temperature fluctuations of the interrogation beam optics. Without an independent measurement, the cold atom interferometer cannot distinguish platform …
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Germanium-rich silicon-germanium materials for field-effect modular application
… consumption, key requirements for integrated modulator applications. This thesis presents a study of the Franz-Keldysh effect in germanium (Ge) layers epitaxially grown on Si substrates, by using free-space spectral responsivity measurement. Generalized Franz-Keldysh formalism and separately …
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RF hardware design of a stepped frequency continuous wave ground penetrating radar
… coupling signal was implemented, using a bi-phase modulator to generate the cancelling signal in antiphase to the coupling signal. A 20 dB reduction in coupling was shown. The system was used to measure cable lengths to within the inherent accuracy of the system. A metal plate target was …
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Polarization-independent Liquid Crystal Devices
… (LC) devices can be operated as amplitude modulators and phase modulators. LC amplitude modulation is commonly used in liquid crystal display (LCD) while phase-only modulation is useful for laser beam steering, tunable grating, prism, lens, and other photonic devices. Most LC devices are …
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Generation and storage of ultrashort pulses using optical fiber devices
… Gbit/sec packet of ONES and ZEROS loaded into a phase modulated optical fiber ring buffer were experimentally investigated. A new mode of operation was explored where the cavity length of the buffer was slightly detuned from the modulation frequency that was driving the phase modulator. An …
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Modeling and control of three-phase PWM converters
… and average models are developed for major three-phase PWM converters. The models are correct for the case when the voltage sources or capacitors with nonzero parasitic resistances are placed across the converter dc port or ac terminals. The effects of the parasitic resistances are described by …
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Nonlinear Photonics in Waveguides for Telecommunications
… Second, a silica/electro-optic (EO) polymer phase modulator with an embedded bowtie antenna is proposed for use as a microwave radiation receiver. The detection of high-frequency electromagnetic fields has been heavily studied for wireless data transfer. Recently there has been growing …
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High Birefringence And Low Viscosity Liquid Crystals
… we have developed a polarization independent phase modulator by using a negative dielectric anisotropic LC gel. With ~20 % of polymer mixed in the LC host, the LC forms polymer network which, in turn, exerts a strong anchoring force to the neighboring LC molecules. As a result, the operating …
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Studies Of Liquid Crystal Response Time
… the grayscale switching behaviors of the LC phase modulators. In conclusion, this dissertation has solved some important issues related to LC optical response time and supplied valuable tools for scientists and engineers to numerically analyze the LC dynamics.