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Showing 1 to 20 of 23 for “"Femtosecond lasers"”.
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Determining molecular chirality with femtosecond LASERs
… with multiphoton ionisation using femtosceond LASERs, it is possible to study the ultrafast dynamics of these chiral molecules.<br/><br/> In this thesis I present a simple device created at QUB that is capable of measuring the PECD effect using stereo-electron detection to directly measure the …
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Compact Femtosecond Lasers for Multiphoton Imaging
… Vertical External Cavity Surface Emitting Lasers (VECSELs), also called Semiconductor Disc Lasers (SDL) are nowadays capable of producing sub-100-fs pulses, multi-kW peak powers, and mode-locking has been demonstrated for wavelength range from 675nm to >2 microns. These flexible, low cost …
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High repetition rate fiber and integrated waveguide femtosecond lasers
Femtosecond lasers and the development of frequency combs have revolutionized multiple fields like metrology, spectroscopy, medical diagnostics and optical communications. However, to enable wider adoption of the technology and new applications like photonic sampling, optical arbitrary waveform …
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Application of Femtosecond lasers in confocal and scanning tunnelling microscopy
This thesis reports the use of a Ti:sapphire ultrafast laser with a confocal microscope to precisely induce DNA damage in the nuclei of live cells by multi-photon absorption, the development and comparison of foci counting algorithms for the quantitative assessment of radiation damage and work …
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Integrated high-repetition-rate femtosecond lasers at 1.55 [mu]m
… sampling can overcome the jitter limit by using femtosecond lasers that have jitter as low as 100 as, which is a three orders of magnitude improvement when compared to electronics. Currently, most of these lasers exist as bulk or fiber lasers. While such configurations can provide flexibility in …
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Novel broadband light sources and pulse generation techniques at 1.5 [mu]m
… for low-repetition-rate sub-100-fs ultrafast lasers and the other for high-repetition- rate femtosecond lasers. The third device bypasses generating broadband light directly from a laser altogether through the use of extra-cavity spectral broadening in a novel highly nonlinear glass fiber. In …
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Femtosecond laser micro-machining and consequent self-assembled nano-structures in transparent materials
… have reported novel developments in the field of femtosecond laser micro-machining within the bulk of transparent materials. Thanks to its unique properties, the femtosecond laser writing technique offers the potential for realizing three-dimensional multi-component photonic devices, fabricated in …
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Physics and Algorithms in Time of Flight Based Computational Imaging
… will utilize advanced electronics hardware like femtosecond lasers, and Single Photon Avalanche Photodiode(SPAD) detectors for the automatic calibration project and software tools meant for machine learning in Python. For optical ultrasound measurement, I will use relatively simple hardware like …
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Studies of third-order nonlinearities in materials and devices for ultrafast lasers
… and Si materials systems were developed for femtosecond lasers and have high reflectivity over 200 to 300 nm bandwidths. These absorbers were designed for modulation depths ranging from 0.3% to 18%. Self-starting modelocked operation with the absorbers was achieved in a variety of lasers …
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Multiscale Insights into Molecular Interfaces: STM Imaging and Ultrafast Laser-Induced Dynamics
… pump-probe STM (OPP-STM) platform utilizing femtosecond lasers was developed and validated. Systematic time-zero calibration and pump-probe experiments, including studies on coproporphyrin I dihydrochloride (CID), confirm the system’s temporal resolution and ability to resolve ultrafast …
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Examining ablation efficiency in alumina ceramics utilizing femtosecond laser with mhz/ghz burst regime /
… avoiding the drawbacks of mechanical processing. Femtosecond laser processing is a suitable technology for processing hard and brittle materials, such as aluminum oxide ceramics (alumina), ensuring high processing quality. However, the processing speed of femtosecond lasers is still behind other …
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Femtosecond laser fabrication of directional couplers and Mach-Zehnder interferometers
The use of femtosecond lasers for photonic device fabrication in glass has become an active area of research in recent years. Since the first demonstration of laser modification of refractive index in glass, a variety of devices such as couplers, interferometers, gratings, 3D structures, active …
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Attosecond timing jitter modelocked lasers and ultralow phase noise photonic microwave oscillators
… drive the needs to develop high repetition-rate femtosecond lasers alternative to Ti:sapphire technology, and to explore a feasible means to achieve integrated photonic microwave oscillators. Ultrafast Cr:LiSAF lasers can be directly pumped with low-cost red laser diodes, and the …
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Plonasluoksnių galio nitrido dangų modifikavimas lazerine femtosekundine UV spinduliuote /
… thermal diffusion time. Most approaches employ femtosecond lasers with wavelengths longer than ultraviolet. However, shorter UV wavelengths could further reduce heat-affected zones due to linear (single-photon) absorption and a smaller focal point, which is directly proportional to the …
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Terahertz-Strahlung auf der Basis beschleunigter Ladungsträger in GaAs
… some mW. Optical excitation with near-infrared femtosecond lasers is possible with repetition rates in the GHz range. The presented results point out the excellent characteristics regarding the emitted THz field strength, average power, spectral properties, and easy handling of the …
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Terahertz Time-Domain Spectroscopy of Low-Dimensional Materials and Photonic Structures
… sensitive detectors. The invention of modelocked femtosecond lasers has made possible the generation and detection of electromagnetic transients on the picosecond to sub-picosecond time scale, which correspond to broadband coherent radiation up to a few or 10’s THz. This time-domain technique has …
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Towards High-Flux Isolated Attosecond Pulses with a 200 TW CPA
… have featured complementary near infrared (NIR) femtosecond lasers for instigating electron dynamics. In order to access the benefits of all-attosecond measurements and open attosecond physics to new fields of exploration, the photon flux of these pulses must be increased. One way to boost the …
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EFFECTS OF LASER MACHINING ON STRUCTURE AND FATIGUE OF 316LVM BIOMEDICAL WIRES
… effect on performance. In this study, Nd:YAG and femtosecond lasers with different pulse widths were used to machine AISI 316LVM biomedical grade wires. The mechanical behavior of these materials were evaluated in uniaxial tension, and in cyclic strain-controlled fatigue with the use of a flex …
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3 GHz Yb-fiber laser based femtosecond sources and frequency comb
Many applications require femtosecond lasers of high repetition rate. In the time domain, a higher repetition rate means more pulses in a fixed time period. For nonlinear bio-optical imaging in which photo-induced damage is caused by pulse energy rather than average power, increasing pulse …
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Measuring the Frequency of Light using Femtosecond Laser Pulses
… combs generated by the periodic pulse trains of femtosecond lasers. The output spectrum of such a laser consists of modes equally spaced by the repetition frequency of the pulses and forms a convenient ruler in frequency space. Extending this principle to the intervals between harmonics of the …
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