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 21 for “"transverse mode"”.
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Transverse mode selection and brightness enhancement in laser resonators by means of volume Bragg gratings
The design of high power lasers requires large mode areas to overcome various intensity driven nonlinear effects. Increasing the aperture size within the laser can overcome these effects, but typically result in multi-transverse mode output and reduced beam quality, limiting the brightness of the …
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Equatorial F -Region Plasma Density Estimation With Incoherent Scatter Radar Using a Transverse -Mode Differential -Phase Method
The full correlation method is formulated and applied to the June 2002 data. Compared to the differential-phase method, this method is different in the sense that it utilizes the real and imaginary parts of the cross-correlation of orthogonal antenna outputs at the high altitudes where SNR is low …
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Reliability and Mode Behavior of AlGaAs-GaAs-InGaAs Quantum Well Heterostructure Lasers
… vertical cavity surface emitting lasers. Transverse mode behavior depends upon the length of the cavity and the tailoring of the ends due to the scattering method used at the Fabry-Perot interface. Data are presented on ten-stripe AlxGa1_xAs-GaAs-InYGa1_YAs quantum well heterostructure …
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Controlled Lasing in Gallium Nitride Nanowires
… lasers operate in naturally-occurring multi-mode and randomly polarized states. Lasing control in nanowire lasers is strongly desired for many practical applications. For instance, specifically polarized lasing is desired for atom trapping and biological detection, and single-mode lasing is …
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Novel approaches to power scaling of single-frequency photonic crystal fiber amplifiers
… power scaling is explored. Instabilities in the transverse mode is observed at increasing output powers. Mitigation of this effect is demonstrated experimentally. This empirical data is used as the basis for a theoretical treatment of the problem, which provides direction for future fiber …
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Donor-Induced Layer Disordering via Silicon Diffusion in Aluminum-Gallium Arsenide - Gallium-Arsenide Quantum-Well Heterostructures, and Disorder-Defined Index-Guided Stripe Geometry Laserdiodes
… (3-(mu)m stripe) and operate in the lowest-order transverse mode.
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High power pulsed ytterbium doped fibre lasers and their applications
… fiberized, polarisation maintaining, single transverse mode system. The full project included the development of the necessary diode & micro-optic systems, fibre beam delivery technology and with application focused evaluations in collaboration with our industrial partners. The main project …
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Femtosecond pulse generation in surface-emitting semiconductor lasers
… goal of stable ultrashort pulse generation in mode-locked optically pumped vertical external-cavity surface-emitting lasers (VECSELs). Continuous wave VECSELs were first designed as a type of semiconductor laser capable of producing high output power in near transform-limited beams. Optical …
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Baseline finite element modeling of government bridge
… paper discusses the creation of a finite element model of Government Bridge, located between Rock Island, Illinois and Davenport, Iowa, a historic structure dating back to the late nineteenth century, to help develop these indices and verify the efficacy of utilizing structural health monitoring …
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Piezoelectric micro-machined ultrasonic transducers for medical imaging
… with the development of an effective single cell model that is further scaled to optimize multi-cell elements in a 1D array. In the first half of this work, a transverse mode, lead zirconate titanate (PZT) pMUT plate cell is fabricated using common micro-fabrication techniques and a PZT sol-gel …
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Experimental characterization of Cr4+:YAG passively Q-switched Cr:Nd:GSGG lasers and comparison with a simple rate equation model
… comparison and anlysis of a laser rate equation model and the laboratory performance of passively Q-switched microlasers. The laser rate equation model describes the development of a top hat gain distribution taking into account the excited state absorption of the passive Q-switch. The lasers …
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High-power single-mode vertical-cavity surface-emitting lasers
… their features. Those that operate in the single-mode regime with sufficiently high power are of particular interest because of the need for an energy-efficient solution to the shrinking bit size in hard disk drives. This work addresses this problem by a careful study of the state-of-the-art …
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Determination of thermo-optic coefficient for B2O3 and GeO2 co-doped optical silica fiber
… a potential method to decrease the influence of transverse mode instability (TMI). Measurements of thermo-optic coefficients (TOC) in five different optical silica based fibers are presented here. One of them is doped with GeO2 in the core and the remaining four fibers are co-doped with B2O3 and …
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Spectral properties and modes of surface microcavities
… the experimental investigations into the transverse mode structure of nearly hemispherical microcavities. The nearly hemispherical microcavity structures are fabricated electrocemically through a template of self assembled latex spheres. Controlling the electrochemical parameters, such as …
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The scattering of thermal phonons by extended defects in dielectric crystals
… from the·grain boundaries. In light of available models of phonon scattering, this suggests that the grain boundaries are sessile. Measurements of phonon scattering at a 10 deg. grain boundary in silicon using direct generation and detection of ballistically propagating heat pulses were made over …
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Classical and quantum nonlinear optics in confined photonic structures
… lower energies as they propagate in the lowest transverse mode of the fibre. The number of solitons and the amount that they shift both increase with the launched power. All of the data is quantitatively consistent with solutions of the nonlinear Schrodinger equation, but only when the Raman …
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Single cancer cell detection with optofluidic intracavity spectroscopy
… and analyzed. To quantify the strength of transverse modes in their spectra, a single characteristic parameter was determined for each cell by forming a linear combination of the mean and standard deviation of the transmission spectra over one free spectral range excluding the residual …
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Exciton-polaritons in thermal equilibrium : from Bose-Einstein condensation to exciton-polaritonics
… polarizabilities in quantum wells to the transverse mode of the confined optical field in the cavity. The light-matter dual nature allows direct control of polaritons through either their excitonic or photonic components. By utilizing the fact that polariton-exciton and polariton-polariton …
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Modulation approaches of vertical-cavity surface-emitting lasers with mode control
… 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 current density of less than 6 kA/cm2 because the current …
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