Fiber Mach-Zehnder Interferometer Based Temporal Light Pulse Manipulation And Microwave Photonic Filter

Slow fast light effects,also called temporal light pulse manipulation,and microwave photonic filters are hot spots in the research field within the past decades.They are both interdisciplinary directions which combine optical methods and microwave technologies together.Slow fast light effects have a wide range of potential applications in all optical communication,such as in realizing optical buffering and optical storage,meanwhile it is be of application value in enhancing nonlinear effects,optical sensing and optically controlled phased array radars.And microwave photonic filters,are be of use in optical microwave signal processing,optically controlled phased array antennas,radio over fiber systems,optical microwave generation.Slow fast light effects are based on the manipulation of the group velocity of the light pulses,and that,microwave photonic filters are based on microwave processing using optical methods.As the group velocity of light is defines as the velocity of the peak of the wave-packet,it detection method involve electro-optic and optic-electro conversion.They have an overlapping part between slow fast light and microwave photonic filters.Slow fast light effect can be used to controlling the phase of the taps in microwave photonic filters,and for some structures as microwave photonic filters,there are slow fast light effects at the same time.Slow fast light can be divided into two kind: material slow fast light and structural slow fast light.This thesis focus on the latter kind.We experimentally find and theoretically proved that there is an effect called cross intensity modulation in an unbalanced fiber Mach-Zehnder interferometer,and it can sustain slow fast light in theory.In experiment,through introducing loss of the optical intensity in two arms of the Mach-Zehnder interferometer asynchronously,we achieved maximum temporal shifts of the light pulse wave-packet with frequency at the transmission minima.It is the first time that slow fast light effect are realized in an unbalanced fiber Mach-Zehnder interferometer.Compared with the former schemes,our scheme has the advantages of flexible designing,simple structure and without limitation of modulation frequency or delay-bandwidth product.In the second part of our thesis,we report a microwave photonic filter based on a fiber Mach-Zehnder interferometer with inserted linearly chirped fiber Bragg gratings.In this scheme,we take advantage of the properties of the chirped gratings,such as long grating length,large bandwidth and large dispersion.The two chirped gratings we used are basically identical,the grating length is 16 cm,the bandwidth is 2.29 nm for each of them,and the dispersions are ?1137ps/nm.Through reversely inserting them into the two arms of the Mach-Zehnder interferometer,we achieved a two-tap microwave photonic filter,we theoretically analyzed the principles.By adjusting the carrier wavelength,the tunability of the filter is achieved.Our filter is of fine and continuous tunability,designable,and the precision of the tunability is at the magnitude of sub-megahertz.It might be of reference meanings in practical applications.