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Full-Text Articles in Other Engineering

Analytical Modeling And Characterization For Avalanche Photodiodes, Erum Jamil Jul 2017

Analytical Modeling And Characterization For Avalanche Photodiodes, Erum Jamil

Optical Science and Engineering ETDs

For applications requiring the detection of low light levels, avalanche photodiodes (APDs) are the preferred detector of choice. The reason for this is their internal gain, which improves the APDs sensitivity (up to 5 − 10 dB) when compared to PIN-based photodiodes. The internal gain for an APD comes from the process of impact ionization process; however, due to its stochastic nature, the multiplication gain comes at the expense of extra noise. This multiplication noise, called the excess noise, is a measure of the gain uncertainty. Despite significant progress made in the fabrication process for the APDs, the excess noise remains ...


Anisotropy And Emission From Air With Laser Filaments, Mohammadamin Rasoulof May 2017

Anisotropy And Emission From Air With Laser Filaments, Mohammadamin Rasoulof

Optical Science and Engineering ETDs

Laser filaments are extremely interesting entities for their unique characteristics. The high intensity inside the laser filaments creates nonlinear effects that are useful in many areas of optics. The laser filamentation is an appealing tool in the stand-off spectroscopy for its ability to propagate over long distances while maintains its extreme intensity. However, depletion of energy hinders its propagation over any desired distance. In order to understand the effect of laser filaments on the transparent medium that they propagate through, one needs to investigate interaction of the laser filaments with the constituents of media. In this work we study the ...


Spatio-Temporally Resolved Optical Laser-Induced Damage To Study Defect Limited Performance Of Optical Films, Yejia Xu May 2017

Spatio-Temporally Resolved Optical Laser-Induced Damage To Study Defect Limited Performance Of Optical Films, Yejia Xu

Optical Science and Engineering ETDs

Laser-induced damage (LID) limits the performance of optical films and surfaces. Despite intensive study for decades following the invention of laser, the study of LID remains timely and attractive, because for nanosecond laser pulses the LID process is controlled by randomly distributed defects of unknown origin.

Traditional damage tests yield little information about the defects present in optical films and surfaces. These methods record a "yes" or "no" damage result after each test and cannot distinguish the different defects present.

This dissertation focuses on the development of a new kind of laser-induced damage test that measures the actual fluence (intensity ...


Synchronous Generation And Coherent Control Of Extreme Wavelength Radiation And Ultrafast Spectroscopy, Aram Gragossian Jan 2017

Synchronous Generation And Coherent Control Of Extreme Wavelength Radiation And Ultrafast Spectroscopy, Aram Gragossian

Optical Science and Engineering ETDs

Recent progress in ultrafast laser science has made it possible to synthesize and control complex electromagnetic waveforms down to sub-femtosecond timescales. These tailored ultrashort laser pulses can generate coherent bursts of electromagnetic radiation in the extreme ultraviolet (XUV) and terahertz spectral regions with durations reaching the attosecond regime in the XUV region. This is accomplished by coherently controlling electronic motion in gas plasma targets. With these novel radiation sources, ultrafast time-resolved spectroscopy can be performed on a large variety of materials. Knowledge of the spectral phase of an ultrashort pulse is crucial for many applications. There are a variety of ...