UWB Optical Pulse Generation Based On Fano Resonance

Generating ultra-wide band(UWB)pulses with an optical method is an important function and application of microwave photonics,which attracts widely interest in academia and industry.Traditional electrical generation approaches are limited by the bandwidth bottleneck of electronic devices.Optical methods have inherent merits like low loss and wideband as well as light weight,small volume,tunability,and immunity to interference etc.In this thesis,we propose an integrated device that generates UWB optical pulses based on Fano resonances.Asymmetric Fano resonance line-shape is produced by a ring-coupled Mach-Zehnder interferometer(MZI)when the phase difference between two arms of the MZI satisfies a certain condition.UWB optical pulses of monocycles,doublets,and higher orders are generated when a radio-frequency(RF)driving signal is applied to the PN junction in the racetrack ring resonator.The thesis demonstrates the structure of the device as well as the fundamental theory of every element,then mathematical modeling is implemented for simulation.The principle of modulation to generate UWB pulses based on Fano resonances is elaborated before the system simulation.At last,static tests for each element is operated and experimental results of UWB pulses generation including temporal waveforms and electrical spectra are presented.The integrated chip for UWB signal generation has the advantages of simple principle and easy realization.It greatly reduces the complexity of the microwave photonic system,opening the possibilities of generating UWB pulses with integrated photonics.