טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentAtkins Shimie
SubjectTemporal Talbot and Related Dispersion Effects with
Applications in Light Pulse Propagation in Fibers
and Fiber Lasers
DepartmentDepartment of Electrical Engineering
Supervisor Professor Emeritus Baruch Fischer


Abstract

   In the temporal Talbot effect a pulse train is reproduced after propagation along specific lengths in dispersive media, such as optical fibers. In the first part of this work we studied applications of this dispersive phenomenon. We examined propagation at fractions of the Talbot length, where pseudo multiplication is obtained. We converted this pseudo multiplication into real multiplication all-optically and passively by adding a nonlinear element. The conversion was performed by cross gain modulation in a semiconductor optical amplifier, where the phases of the pulses in the train are eliminated. We were able to obtain pulse rates of ~40 GHz from a pulse train of ~10 GHz. In addition, we demonstrated operation of a long fiber laser at fractions of the Talbot length.

   In the second part of this work we performed experiments with fiber lasers where localization occurs in the frequency regime. Mode-locked lasers were shown to be an optical analog to the quantum kicked rotor. Here, broad light pulses that are repeatedly kicked by a sinusoidal rf phase modulation and then propagated along equally spaced lengths of fiber are confined in frequency.  We performed experiments showing the evolution and the steady state behavior of such a system.

   In the third part of the work we used “time-lens” operation to achieve real time spectral analysis of light pulse trains. The time-lens is a temporal analog to the spatial lens, obtainable by a sinusoidal phase modulator, where each pulse in the train recieves quadratic modulation, thereby focusing or spreading each pulse. In this application we perform a Fourier transform of the input signal so that its spectrum is represented in the temporal envelope of the output signal, thus providing us with a spectral analyzer.