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 24 for “"Picosecond pulses"”.
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Pulsed laser induced breakdown in solid state materials and air
… LIDT compared to scaling derived from sub-picosecond pulses. Linear polarization produces lower LIDT than circular polarization for MPA order of m=3 and 4 with femtosecond and picosecond pulses. Laser damage tests with two-color pulse pairs show that the damage threshold depends on the …
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Development of ultrashort pulse fiber lasers for optical communication utilizing semiconductor devices
… mode-locking is considered theoretically. Picosecond pulses are produced from an Er/Yb waveguide laser using a semiconductor saturable absorber mirror, and the influence of two-photon absorption on mode-locking is studied. A semiconductor mirror exhibiting only induced absorption is used to …
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Wideband high-power transmission line pulse transformers
… transformer capable of transmitting kilovolt 100-picosecond pulses from a parallel plate geometry into a coaxial geometry, modeled after a transverse electromagnetic (TEM) cell. The transformer operates on a wide frequency bandwidth (.5-2 GHz) with minimal reflection or radiative loss (>1.5 dB …
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A few-cycle Cr⁴⁺:YAG laser and optical studies of photonic crystals
… Cr4+:YAG laser was used to generate 20 fs pulses at 1450 nm with a bandwidth of 190 nm FWHM. Intracavity group velocity dispersion was compensated with double-chirped mirrors. Pulse spectrum was observable from 1140 to >1700 nm. Broadband saturable Bragg reflectors were designed and used to …
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COMPLETE TEMPORAL MEASUREMENT OF LOW-INTENSITY AND HIGH-FREQUENCY ULTRASHORT LASER PULSES
… complete temporal measurement of low-intensity picosecond pulses in the near-infrared (NIR) and intense ultrashort pulses in the ultraviolet (UV) and extreme ultraviolet (EUV). The former are projected to find great use in the field of optical telecommunications, while the latter are the result …
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Nonlinear applications of step-index and microstructured soft-glass fibres
… an all-optical regenerator of Return-to-Zero picosecond pulses is realized at repetition rates of 10 and 40 Gb/s. The same fibre is also employed in an all-fiberised pulse compression scheme, which relies on nonlinear pulse propagation in the normal dispersion regime and enables the …
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Didelės energijos keturių lėkių Nd:YAG stiprintuvas su SBS impulso spūda interferenciniam struktūravimui /
… [10], and water resistance improvement. Picosecond laser pulses are the most relevant for material surface structuring due to their simplicity and versatility: 100 ps order laser pulses have enough intensity to create multi-photon absorption, and they do not induce plasmoid interactions, …
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Femtosecond pulse generation in surface-emitting semiconductor lasers
… Stark effect allowing VECSELs to produce sub-picosecond pulses in transform-limited beams, at power levels up to 100 mW and at GHz repetition rates.<br/>The work presented in this thesis describes recent progress in reducing the durations of VECSEL pulses to below 100 fs. At these pulse …
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External Cavity Multiwavelength Semiconductor Mode-locked Laser Gain Dynamics
… semiconductor mode-locked lasers can produce pulses of a few picoseconds. The pulses from these lasers are inherently chirped with a predominant linear chirp component that can be compensated resulting in sub-picosecond pulses. External cavity semiconductor mode-locked lasers can be configured …
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The impact of WH/TS codes in implementing incoherent OCDMA system
… incoherent OCDMA codes which use multiwavelength picosecond pulses. The encoders/decoders are based on fibre Bragg gratings (FBG) technology and the investigations were carried out at OC-48 (2.5 Gb/s) data rate. The testbed was built to be a fully chromatic dispersion compensated with …
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Design of a 250 GHz gyrotron amplifier
… nuclear magnetic resonance spectroscopy with pulses as short as several hundred picoseconds. This design will be implemented at a later date for the construction of the highest frequency, kW power level amplifier based on vacuum electronics. To gain understanding of short pulse amplification …
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Semiconductor seeded fibre amplified sources of ultra short pulses
… VECSELs are a compact source of ultra-short pulses at GHz repetition rates, with pulse lengths as short as 190 fs being generated directly from the laser. The VECSEL is a power scalable device offering spectral versatility through band gap engineering of semiconductor gain …
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Aufbau eines 500 Hz-Lasersystems zur Summenfrequenzschwingungsspektroskopie
… on the design and performance of a 500 Hz picosecond laser system specifically developed for sum-frequency spectroscopy of molecular vibrations at interfaces, and on its applications to the study of potential-dependent CO adsorption at the Pt(111)/aqueous electrolyte interface. The …
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Optical pulse distortion and manipulation through polarization effects and chromatic dispersion
… then apply the dispersion of the ultra-long FBG. Picosecond pulses are formed, whose repetition rate is independent of the laser cavity length. Since the gain of the laser is not modulated, the timing jitter is fundamentally limited only by the frequency noise of the laser. Finally, we again …
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Optical transient grating measurements of micro/nanoscale thermal transport and mechanical properties
… spheres. In the transient grating technique two picosecond pulses are crossed to generate a spatially periodic intensity profile. The spatially periodic profile generates a material excitation with a well-defined wave vector. The time dependence of the spatially periodic material response is …
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Ultrashort pulse generation from diode laser devices
… study of generation of ultrashort optical pulses from diode lasers. Simple and cost-effective techniques were used to generate high power, high quality optical short pulses at various wavelength windows. The major achievements presented in the thesis is summarised as follows. High power …
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Novel Approaches to Power Scaling In Mode-Locked Laser Diode Based Ultrashort Pulse Sources
… built upon the common approach of amplifying pulses from a mode-locked laser diode using a separate semiconductor optical amplifier. In this work, a tapered amplifier was used in a double-pass regime to amplify picosecond pulses for the first time. The double-pass amplifier regime was compared …
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Development of Novel Compact Laser Sources for Bio-Medical Applications
… master oscillator power amplifier (MOPA) picosecond optical pulse sources using all chirped QD structures were investigated using the MOPA system consisting of two parts, firstly QD-ECMLL and secondly a tilted taper QD-SOA. A further investigation involved a comparison between 1st-order …
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Pulsed Laser Dielectric Ablation for Copper-plated Silicon Solar Cells
… the light-matter interaction between short laser pulses and textured silicon nitride (SiNx)/Si surfaces. It is shown that picosecond laser pulses of the longer wavelength of 532 nm result in melting depths of ~ 1 µm and the SiNx being primarily ablated by the indirect ‘spallation’ process, whereas …
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