Study On Broadband Tunable All Optical Wavelength Conversion Based On MgO Doped Periodically Poled Lithium Niobate

In all optical wavelength division multiplexing communication networks, the multiple signals from different transmitters need to be channel routed and dynamic reconfigured rapidly at network nodes, so as to resolve the node wavelength blocking and competition, this is the wavelength conversion technology. Currently the matured wavelength conversions based on semiconductor optical amplifier and O/E/O have more or less defects, such as not strictly transparent to signal format and transmission rate, restricted conversion channels and flexibility, limit their applications in future high-speed and large-capacity optical networks. However, the wavelength conversion based on periodically poled lithium niobate (PPLN) have some dominant merits due to its pure nonlinear optical interaction, such as strictly transparency to signal format and transmission rate, flexibility to realize wavelength broadcasting. So the PPLN converters have attracted much favors and are believed to be the most promising solution to all optical channel routing. In this paper, we study the wavelength conversion in magnesium oxide (MgO) doped PPLN crystal. The main progresses are as follows:1. In MgO:PPLN crystal, we compared the domain inversion periods versus fundamental wavelengths and the second harmonic generation (SHG) efficiency bandwidths between Type 0 and Type I quasi phase matching (QPM). Choosing proper poling period and operating temperature, we obtained the Type I QPM broadband SHG and sum frequency generation (SFG).2. We proposed two wavelength conversion broadcasting schemes based on the broadband effects: single pump cascaded SHG/DFG and double pump cascaded SFG/DFG. We broadcasted one signal to seven channels utilizing the two schemes, also the flexible conversions shifting one signal to single, double and triple channel were demonstrated via selecting different pump wavelengths within the broadband.3. We measured the conversion efficiency of the two schemes and attempted to convert the 2.5GHz NRZ (Not Return to Zero) format signal. The trial urges us to summarize the facing deficiency and forwards the expectation to implant waveguide structure in MgO:PPLN crystal to enhance conversion efficiency.