Dual Loop Optical Buffer Based On Collinear 3x3 Fiber Coupler

In the longer term, fiber communication network will go towards all-optical network and the bandwidth efficiency associated with optical packet switching will be required to ensure economic use of network resources. Optical buffer is one of most important element in optical packet switching network.This thesis reveals all kinds of buffering effects based on a collinear 3x3 fiber coupler, bringing forward two structures of optical buffer: recumbent '8' structure and upright '8' structure, called as Dual Loop Optical Buffer (DLOB). Theoretically and experimentally studies show, that DLOB with upright '8' structure is more stable than other. Two DLOBs with different nonlinear element are proposed, and especially key issues in them are inverstigated. A lot of results from this thesis are useful for all optical signal processing and all optical switching.The innovations of this thesis are as follows:1, Studies on the collinear 3x3 fiber coupler which is the fundamental element of DLOB. Discovers how unsymmetricalness affect split ratio of the coupler and its broad-band and polarization maintained characteristics. Fabricates a collinear 3x3 fiber coupler with special split ratio.2, Brings forward upright '8' structure buffer in which two loops are arranged like an upright digital number '8' and discusses its output stability. Designs feedback compensation method to stabilize the buffer's output and examines its effect through experiment.3, Brings forward a 3-port optical switch that is used as read/write control for DLOB and is the base of DLOB with two same-state ports.4, Brings forward a DLOB in which SOA is used as the nonlinear element and studies the buffering principle in it. Devises its experiment system and carries out buffering experiment with a single pulse and a planed frame pattern at different bit rates. 5, Brings forward a simple noise model and studies background noise in DLOB based on it. Studies the relationship between signal to noise ratio and loop circulations and get its theoretical curves. Brings forward a technical scheme to suppress the noise in DLOB by adding base onto control light pulse.