All-Optical Digital Signal Processing Based On Ppln Waveguides

In the present high-speed optical communication networks, all-optical signal processing is developed and applied widely because it can break through the speed limitation brought in by the troditional optical-electronic-optical switch. All-optical digital signal processing is one of the present focuses, because it can recover the speed limit of optical-electronic-optical switch of digital signal processing in optical network, and it is the necessary technology of future ultra-high speed optical network and all-optical network. PPLN waveguide is one of the waveguides with the optical second-order nonlinear materials, and it uses the quasi-phase matching technology. PPLN waveguides have the advantages of high efficiency, low noise, rapid response and convenient integrity. This paper makes theoretical analysis and numerical calculation in all-optical digital signal processing base on PPLN waveguides, and achieves creative achievements of researchment as follows:1. As the basis of researchment on the application of PPLN waveguides on the all-optical time domain multiplexing, and propose an optimum scheme of all-optical time domain multiplexing based on the PPLN waveguides. The relationship of three parameters—waveguide length, pulse width of pump light, and pulse offset of pump light is analyzed theoretically and numerically. By adjusting these three parameters, the scheme obtains the maximum conversion efficiency and maintains the crosstalk power below the given threshold. All-optical time domain multiplexing deals with the pulse-train optical signals, and it has the instructive significance on researching the all-optical digital signal processing based on PPLN waveguides.2. PPLN waveguide cascading is proposed firstly in this paper on the basis of digital signal processing based on single PPLN waveguide. This paper demonstrate the requirements of waveguide cascading, analyzes the principle of two-waveguides cascading configuragions theoretically, and verifies the feasibility of waveguide cascading. PPLN waveguide cascading can achieve more various and complex technologies of all-optical digital signal processing, expands the potential ablity and more development of PPLN waveguides on future all-optical digital signal processing.3. The scheme of all-optical full-adder based on the cascaded PPLN waveguides is proposed on the basis of the all-optical logic gates and all-optical half-adder. The scheme achieves two output signals of all-optical full-adder with three input signals based on a five PPLN waveguides configuration. The output signals of all-optical full-adder are analyzed by numerical simulation, and the results of simulation meet the theoretical analysis well, with the acceptable signal quality.