We have demonstrated a guided-mode resonance filter (GMRF) whose properties are tunable with laser illumination through the incorporation of a nonlinear dye. Laser illumination causes a change in the refractive index of the dye-doped portion of the structure, leading to controlled tuning of the GMRF reflectance spectrum. Changes in the refractive index of dye-doped regions are proportional to t...

We carry out wavelength-dependent second harmonic interference experiments using thin films of an organic dye as nonlinear optical sources. While the measured difference of refractive index between the fundamental and second harmonic wavelengths follows the theoretical expectation for air in a wide spectral region, anomalous dispersion is observed when the second harmonic light lies in the abso...

Eigenmodes of three-wave interactions in second-order [X((2))] nonlinear materials are explored that have a noenergy-exchange property between all the waves. They are shown to exhibit cross-induced nonlinear refraction and to be ideal candidates for amplitude-dependent phase control in X((2)) materials that emulate nonlinear refractive-index effects in third-order [X((3))] materials. It is show...

The intensity of a He–Ne laser ~633 nm, 5 mW! transmitted by different GaSe samples is observed to change in correlation with a Nd-yttrium–aluminum–garnet laser pulse ~532 nm, 7.8 ns, 3 mJ! which excites them. Such time response has been attributed to a nonlinear optical effect, i.e., a decrease in the refractive index due to the exciton screening by the photogenerated carriers. A calculation o...

In optical tomography, conventionally the diffusion approximation (DA) to the radiative transport equation (RTE) with a constant refractive index is used. The existence, uniqueness, and non-uniqueness of the forward and the inverse problem using conventional DA has been studied in the past. In this report, we investigate the existence, uniqueness, and non-uniqueness of optical tomography forwar...

We directly measure the nonlinear optical response in argon and nitrogen in a thin gas target to laser intensities near the ionization threshold. No instantaneous negative nonlinear refractive index is observed, nor is saturation, in contrast with a previous measurement [Opt. Express 17, 13429 (2009)] and calculations [Phys. Rev. Lett. 106, 183902 (2011)]. In addition, we are able to cleanly se...

As optical communication systems continue to advance in speed and complexity, the demand grows for high-speed devices to perform wavelength conversion, multiplexing, and switching operations. Semiconductor diode laser amplifiers exhibit large and ultrafast optical nonlinearities that make them promising candidates as the basic building blocks for such all-optical devices. The primary goal of th...

We experimentally generate different types of two-dimensional self-trapped photonic lattices in a photorefractive medium and analyze the induced refractive index change using two different methods. One method gives the first experimental Fourier space analysis of both linear and nonlinear self-trapped photonic lattices with periodic phase modulation using partially spatially incoherent multiban...