Nonlinear optical structures with unique spatio-spectral characteristics.

摘要

One-dimensional quasi-phase matching has attracted a great deal of attention in the field of wavelength conversion. The focus of the research has mainly been on increasing the efficiency of the frequency conversion process with little or no attention to the spatial segregation of the nonlinear output from the unconverted inputs. This dissertation studies three new optical devices, which we have developed, that possess unique spectral and spatial characteristics—the M-waveguide, the bisected intersecting waveguide and nonlinear photonic crystals. In addition, the thesis presents and demonstrates simultaneous optical wavelength interchange, which is both the first telecommunication application of nonlinear photonic crystals and the first one-step optical carrier interchange process.; M-waveguides provide a new method for second-order nonlinear upconversion processes and can be designed to be perfectly phase matched without the use of birefringence or quasi-phase matching. M-waveguides have an output wave profile that is single-lobed in the core region and are ideal candidates for monolithically integrated circuits. The bisected intersecting waveguide in periodically poled lithium niobate can produce and isolate the second-order optical product free from the unconverted inputs and near degenerate harmonics.; We also present the theoretical analysis and the first experimental demonstration of simultaneous optical wavelength interchange by use of two concurrent difference-frequency-generation processes in a two-dimensional second-order nonlinear photonic crystal fabricated in lithium niobate. We have derived a set of relations, including a general nonlinear Bragg condition, that we use to determine the parameters of the nonlinear lattice, given the input wavelengths and desired exit angles of the wavelength-interchanged outputs. Theoretical analysis of some properties of these devices such as crosstalk and efficiency is also addressed. Future applications of nonlinear photonic crystals in telecommunications systems is discussed.