M.Sc Thesis

M.Sc StudentLevinson Oren
SubjectGeneration of Complex Microwave and Millimeter Wave Pulses
using Electro-Optical Systems.
DepartmentDepartment of Electrical and Computer Engineering
Supervisor PROF. Moshe Horowitz


Optoelectronic systems can increase the bandwidth, improve the performance and reduce the size and the power dissipation of microwave electronic systems. Electrical broad-spectrum pulses are used to improve the performance of Radars based on pulse compression and in communication systems based on spread spectrum technique. In this work we demonstrate a new method to synthesize complex microwave and millimeter wave pulses, modulated by a complex amplitude profile that can be easily controlled without the need of complex high frequency electronic circuits.  The technique is based on converting the interference of two optical pulses that propagate in a fiber system with dispersion, group delay, and Kerr effect, into an electrical pulse by an optical detector. We analyzed theoretically a system based on a polarization change induced in an optical pulse that propagates in a birefringent fiber. The polarization changes are converted to intensity changes using a polarizer and then to electrical signals using an optical detector. Implicit results are given when the dispersion or the nonlinear effect can be neglected. A simple method for implementing the system, based on using an interferometer and a fiber Bragg grating is demonstrated. We experimentally demonstrated the generation of microwave pulses modulated with a constant instantaneous frequency using a linear chirped fiber Bragg grating. Pulses modulated with a linear frequency chirp were generated using a Michelson interferometer and two chirped fiber gratings with different dispersion slopes.