Investigation Of All-Optical Flip-Flop And Its Application

All-optical flip-flops (AOFF) are key devices for realizing many functionalities in optical networks and optical computing, especially as all-optical memories for the temporary storage of decisions in photonic packet routers. In this paper, we investigated three kinds of AOFFs theritically and experimentally. The conclusions of this paper are significant for the development of the all optical signal processing. The followings are some innovative works I have done:1. A novel optical flip-flop based on single Fabry-Perot Laser Diode (FP-LD) was proposed. Two Fiber Bragg Gratings with different wavelength were used to reflect the output power of the FP-LD, and make the FP-LD work under the bistability condition. This scheme is lower cost, easy for integration, and reduces the affect of wavelength fluctuation to the AOFF.2. The graphic method is proposed to analysis the Fiber Ring Laser (FRL) for the first time. The graphic method gets rid of complex calculations and is used to analyze the lasing and quenching process of the FRL. According to the Graphic Method, we obtain that the lasering and quenching process is influenced by the feedback factor of the FRL. The eternal inject optical power is also a key factor that influences the laser suppression, the bigger the power is and the shorter the laser suppress time is.3. The graphic method is used to analyze the bistability property of the coupled FRL. The important factor of the coupler structure to realize bi-stability is the couple split ratio between the two FRLs. The graphic method is also used to analyze the functional properties of the AOFF.4. The Poincare Sphere method is used to analyze the Nonlinear Polarization Rotation (NPR) effect of SOA for the first time. The PS method is applied to describe the variations of ellipticipy angle and azimuth of SOA output state of polarization (SOP) induced by polarization-dependent gain (PDG) and polarization-dependent phase shift, respectively. The theoretical results reveal that the polarization dependence of the linewidth enhancement factor (LEF) and the variation of SOA gain are significant factors for the NPR. The evolutions of output SOP on the PS under quasi-continuum condition have been demonstrated experimentally. This Poincare Sphere method has been used to optimazing the performance of AOFF based on polarization switch. 5. The polarization dependence of LEF has been measured for the first time. The result reveals that the polarization dependence of LEF plays an important roll in the NPR effect of SOA.6. The concept of synchronous pulse expanding has been proposed for the first time, which is an important technology for the optical packet switching network node. The synchronous pulse expanding scheme of AOFF cascaded with optical buffer has been demonstrated. In the experiment, the narrow input light with 0.5μs pulse width has been synchronously expanded to 44μs and 68μs respectively.