Multifunctional optical signal-processing devices in periodically poled lithium niobate

Optical signal processing is becoming an attractive technology for communication applications. Many important optical signal-processing functions have been demonstrated in devices based on periodically poled lithium niobate (PPLN) waveguides. They are among the fastest and most efficient nonlinear optical devices available today.; The work presented in this dissertation extends the functionality of PPLN optical signal processors by lifting two limitations long imposed on such devices: A broadband quasi-group-velocity-matched scheme is invented to mitigate the bandwidth-efficiency trade-off inherent in optical frequency mixers, and several techniques are developed to modulate the nonlinear interaction amplitude and thereby versatilely shape the transfer function of an optical signal processor.; The ability of optical signal processors to process high-speed data beyond what is possible with electronics has been applied to optical time-division multiplexing (OTDM). Multiple functions are tailored and monolithically integrated to make a PPLN-based optical time-division multiplexer (OTDM-MUX) capable of 160-Gbit/s operation. Its integrated operation is successfully demonstrated. Compared with previously demonstrated OTDM-MUXs, besides the advantages of a monolithic layout, the PPLN MUX has higher efficiency while keeping crosstalk low.; Engineered nonlinear optical and optical circuit components have opened the door to a new level of versatility of PPLN-based optical signal-processing devices.