The authors review progress in the application of nonlinear optical phenomena to integrated optics. Essentially all integrated optics devices such as directional couplers, Mach-Zehnder interferometers, prism couplers, etc., can be used for all-optical signal processing when at least one of the waveguiding media exhibits an intensity-dependent refractive index. Experimental and theoretical results on the operating characteristics and figures of merit of such devices, as well as a new class of phenomena based on large nonlinear changes in waveguide properties will be summarized. Also discussed are measurement techniques for evaluating waveguide nonlinearities. Progress in the implementation of other nonlinear third order interactions, such as degenerate four-wave mixing and nonlinear spectroscopy, will also be reviewed. >

Third order nonlinear integrated optics

A new treatment of the behavior of TE nonlinear waves in an optically nonlinear film is given. The new mathematical results are expressed in terms of the physical parameters of the system and represent a straightforward way to introduce the necessary Jacobian elliptic functions. The optical nonlinearity is of the Kerr type and the numerical calculations are performed for a self-focusing medium. Dispersion curves labeled with optical power density at the lower film boundary, detailed plots of the variation of electric field amplitude as the wave number changes, and details of the power distribution across the guide are given. Since two values of a wave number can exist for the same power level and power thresholds exist, the system is of device interest in the area of optical switching.

Optically nonlinear waves in thin films

Publisher Summary This chapter describes the nonlinear wave propagation in planar structures. The two categories of integrated all-optical devices can be anticipated on the basis of the nonlinear optical phenomena. The first class of optical devices is that in which the nonlinear change in the refractive index is small in comparison with the refractive index difference between the guiding media. The second category of nonlinear optical devices is that in which the optically induced change in refractive index is comparable with, or larger than, the index differences among the guiding media. The chapter discusses the study of electromagnetic waves guided by nonlinear interfaces. The basic concepts and method used to analyze nonlinear guided wave phenomena are also discussed. The nonlinear TE polarized waves guided by thin dielectric films are studied. The chapter explains that very thin metal films (nonlinear surface plasmon polaritons) can also guide nonlinear TE polarized waves. The experiments reported on nonlinear guided wave phenomena are reviewed in the chapter.

IV Nonlinear Wave Propagation in Planar Structures

Third-Order Nonlinear Electromagnetic TE and TM Guided Waves

We propose new all-optical logic gates containing a local nonlinear Mach-Zehnder interferometer waveguide structure. The light-induced index changes in the Mach-Zehnder waveguide structure make the output signal beam propagate through different nonlinear output waveguides. Based on the output signal beam propagating property, various all-optical logic gates by using the local nonlinear Mach-Zehnder waveguide interferometer structure with two straight control waveguides have been proposed to perform XOR/NXOR, AND/NAND, and OR/NOR logic functions.

New all-optical logic gates based on the local nonlinear Mach-Zehnder interferometer

This paper contains a comprehensive theory, supported by many numerical examples, of the behavior of electromagnetic waves in a potential device that consists of a thin, opticaliy linear film, bounded by dissimilar semiinfinite nonlinear materials with frequency- and wavenumber-independent parameters. The relationship between the electric field amplitudes on the respective boundaries of the film leads to an elegant analysis that results in physical quantities being derived without a quantitative knowledge of the nonlinear fields. Guided and surface waves are precisely differentiated from each other, and it is shown that the linear cutoff criterion generalizes, when nonlinearity is added, to a novel changeover condition. The nonlinear eigenvalue equations are used to give the guided/surface mode index in terms of the optical power density at one of the interfaces. The power flow down the guide is then calculated both as a function of the interfacial optical power density and as a function of the mode index. These are shown to lead to two different sets of dispersion curves labeled with power flow down the guide or the optical power density at the interface. Finally, by assuming that the nonlinear media are lossy, optical hysteresis is shown to be possible.

A. Boardman

Papers

Optically nonlinear waves in thin films

S-polarized waves in a thin dielectric film asymmetrically bounded by optically nonlinear media