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Necati Kaya, PhD 
Texas A&M University, Department of Physics and Astronomy, College Station, TX 77843-4242 
Office & Laboratories: MPHY 466, ENPH 104, ENPH B11 
email: necati@physics.tamu.edu 
Phone: +1 979 422 8958



I have been working with femtosecond laser equipment including oscillators, amplifiers, OPAs, fs-pulse shapers and diagnostic equipment such as CCD cameras, spectrometers, autocorrelators and FROG devices in applications for studies of the interaction of fs pulses with matter and spectroscopy.
Research Interests: Femtosecond Lasers Systems, Laser spectroscopy, Femtosecond beam characterization, Computer Generated Holography (CGH), Ultrashort laser filamentation, White-light generation and control, Above Threshold Ionization (ATI), Molecular alignment of diatomic molecules, Ion Optics and Ion Beam Apparatus (IBA), Fragmentation of Molecules in Intense Laser Fields.


White-light generation using spatially-structured beams of femtosecond radiation
White-light generation is studied in water using spatially- structured beams of femtosecond radiation. By changing the transverse spatial phase of an initial Gaussian beam with a 1D spatial light modulator to that of an Hermite-Gaussian (HGn,m) mode, we were able to generate beams exhibiting phase discontinuities and steeper intensity gradients. When the spatial phase of an initial Gaussian beam (showing no significant white-light generation) was changed to that of a HG01, or HG11 mode, significant amounts of white-light were produced. Because self-focusing is known to play an important role in white-light generation, the self-focusing lengths of the resulting transverse intensity profiles were used to qualitatively explain this production. Distributions of the laser intensity for beams having step-wise spatial phase variations were modeled using the Fresnel-Kirchhoff integral in the Fresnel approximation. N. Kaya, J. Strohaber, A. A. Kolomenskii, G. Kaya, H. Schroeder and H. A. Schuessler, Optics Express 20, 13337 (2012) 


 In this paper we introduce a method for analysis of optical beams by using a folded version of a 2f-2f setup containing spatial phase modulator (SLM). The SLM is proven to be useful in producing diverse “soft apertures” that are difficult or impossible to reproduce mechanically. Phase hologram encoded with phase and amplitude information is used to knife edge the laser modes. Precise phase calibration of the SLM is reported. The measured powers from both mechanical and holographic knife-edge methods are found to be in a good agreement with each other. Important new analytic results are the knife-edge equations for the Hermite-Gaussian and Laguerre-Gaussian modes. In both cases good agreement is found between experiment and theory. Finally, the authors tomographically reconstruct a broadband optical beam in a folded 2f-setup. J. Strohaber, G. Kaya, N. Kaya, N. Hart, A. A. Kolomenskii, G. G. Paulus, and H. A. Schuessler, Optics Express, 19, 14321 (2011)




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