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 20 of 31 for “"Direct Modulation"”.
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Direct modulation of multimode vertical cavity surface emitting lasers
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2001.
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Techniques for high-speed direct modulation of quantum dot lasers
As a major component of optical transmitters, directly-modulated semiconductor lasers are widely used in todays fiber optical link systems by taking its advantage of their low cost, compact size and low power consumption. In this work, techniques to improve the high frequency modulation …
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Adaptive Pre-Distort.ion for Laser Diodes with Direct Modulation Frequencies up to 1 GHz
… (CATV) systems where a single-channel optical modulation index of 4 % is required. By extending the study of the linearized laser, a self-adaptive technique was developed that can appropriately adjust the pre-distorter to laser changes caused by temperature variation and aging. This adaptive …
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Characterization of the Dynamics of Optically-Injected Nanostructure Lasers
The direct-modulation of semiconductor lasers is the simplest and most compact approach to pass data onto an optical fiber; however, their intrinsic limitations under direct-modulation such as wavelength chirp and inherent relaxation oscillation frequency constraints impede their high-speed and …
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Output Characteristics and High-Speed Modulation of Composite -Resonator Vertical -Cavity Lasers
… with the goal of understanding the high-speed direct modulation of these devices from theoretical and experimental perspectives. The epitaxial structure is considered and one dimensional simulations of the mode profile in the CRVCL are used to model several different designs, which are …
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Modeling of DFB surface emitting lasers and semiconductor laser arrays
… single-mode outputs even under high bit-rate direct modulation and form two-dimensional laser arrays. A simple and accurate analytical model using the coupled-mode theory is developed to describe these surface emitting lasers. Due to the simplicity of the model, the desired laser output …
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Electronically tuned 23 GHz Gunn oscillators for a microwave datalink
… 23 GHz is presented. With reference to advanced modulation methods which require constant modulation indices, a method of linearising the voltage/frequency characteristic of the varactor controlled Gunn oscillator is described, which allows direct modulation of the source at 23 GHz. Due to the …
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Direct tunneling modulation and signal mixing of semiconductor lasers
… has the potential to overcome the diode laser’s modulation speed limit by further reducing the carrier recombination lifetime. In addition, a recently discovered tunneling mechanism inside the transistor laser device structure paves the way for ultrahigh-speed direct modulation of laser optical …
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Modulation approaches of vertical-cavity surface-emitting lasers with mode control
… device lifetime, various approaches of digital modulation utilizing VCSELs with modified structures for mode control are presented. Direct modulation of VCSELs with separate optical and current apertures enables high modulation bandwidth of greater than 18 GHz operating single mode at low …
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Design and Control of Mechanoneural Interfaces for Neuroprosthetic Limbs
… mechanoneural interface that allows for the direct modulation of proprioceptive afferents. These advancements have the potential to significantly improve the quality of life for individuals with amputations and further the development of advanced surgical and neuroprosthetic technologies.
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External control of semiconductor nanostructure lasers
… the mode stability, spectral linewidth, and direct modulation capabilities. One possible method to overcome these limitations is through the use of external control techniques. The electrical and/or optical external perturbations can be implemented to improve the parameters associated with …
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Optogenetic regulation of protein activity in live cell
… optochemical experimental strategies that enable direct modulation of cargo trafficking in live cells.
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Enhanced Modulation Dynamic Performance of Optically-Injected Widely-Tunable Semiconductor Lasers
… theoretical and modelling study of dynamic modulation characteristics of semiconductor wide-wavelength tunable laser diodes (TLDs). The two major goals were to investigate how modulation properties of a TLD depend on the wavelength tuning, and how the modulation performance of a TLD can be …
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High-speed modulation of semiconductor lasers and properties of silver-coated quantum-dot lasers
… a desire for high-speed lasers that have a large direct modulation bandwidth and eliminate the need for external modulators. Nanoplasmonic lasers and their high-speed characteristics are thus an important topic of research. In this thesis, experimental techniques for characterizing the high-speed …
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Quantum dot gain-lever laser diode
… their potential for high differential gain and direct modulation with negligible chirp. Recently, substantial efforts have been made to improve the modulation characteristics of QD semiconductor lasers such as enhancing the modulation efficiency and improving the overall modulation bandwidth. …
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Solid-state nanopore sensors for nucleic acid analysis
… remarkable electrical and mechanical properties. Direct modulation of the nanopore conductance was observed through the application of potentials to the graphene gate. These exciting results suggest this technology could potentially be useful in slowing down or trapping a DNA molecule in the pore, …
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NEURAL MECHANISMS SUPPORTING COGNITIVE INFLUENCES ON SUPRASPINAL NOCICEPTIVE PROCESSING: INSIGHTS FROM BRAIN LESIONS
… level may allow cognitive information to directly influence cortical processing of nociceptive information. In contrast to studies that show attenuation or facilitation of incoming sensory information from the spinal cord, these supraspinal neural mechanisms may directly influence how …
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The Role of TBX3 In Early Breast Cancer Progression
… SLUG and TWIST1. Importantly, TBX3 is a direct regulator of SLUG, and SLUG expression is required for TBX3-induced migration and invasion. Assessing TBX3 expression in early stage breast cancers by immunohistochemistry (IHC) revealed high expression in low-grade lesions. Within a second …
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Role of the Endocannabinoid System in Cardiac Remodeling
… ventricular fibroblasts and the effects of their direct modulation on the fibrotic responses were also investigated. Rat model of pressure overload induced by abdominal aortic constriction was used for the in vivo study while the human ventricular fibroblast cell line was used for the in vitro …
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Engineering control of eukaryotic translation with application to the malaria parasite Plasmodium falciparum
… of gene expression, our system is unique in its direct modulation by an exogenous chemical. By genetically encoding TetR-binding RNA aptamers in the 5' untranslated region (5'UTR) of an mRNA, translation of a downstream coding sequence is repressed by TetR in vivo and induced upon adding a …
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