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 described in this dissertation further 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 obviate 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), a technique complementary to wavelength-division multiplexing. In this dissertation, multiple functions are tailored and monolithically integrated to make a PPLN-based optical time-division multiplexer (OTDM-MUX) capable of 160-Gbit/s operation. It is successfully characterized using ultrafast optical techniques. Compared with previously demonstrated OTDM-MUXs, besides the advantages of a monolithic layout, the PPLN MUX has higher efficiency while keeping the crosstalk low.
Beyond discrete functions, engineered nonlinear optical and optical circuit components have opened the door to a new level of versatility of PPLN-based optical signal-processing devices.