Unusual phase transition in 1D localization and its observability in optics

Localization of electrons in 1D disordered systems is usually described in the random phase approximation, when distributions of phases \varphi and \theta, entering the transfer matrix, are considered as uniform. In the general case, the random phase approximation is violated, and the evolution equations are written in terms of the Landauer resistance \rho and the combined phases \psi=\theta-\varphi and \chi=\theta+\varphi. The distribution of the phase \psi is found to exhibit an unusual phase transition at the point E_0 when changing the electron energy E, which manifests itself in the appearance of the imaginary part of \psi. The distribution of resistance P(\rho) has no singularity at the point E_0, and the transition seems unobservable in the framework of condensed matter physics. However, the theory of 1D localization is immediately applicable to the scattering of waves propagating in a single-mode optical waveguide. Modern optical methods open a way to measure phases \psi and \chi. As a result, the indicated phase transition becomes observable.Comment: Latex, 9 pages, 6 figures include

Statistical properties of spontaneous emission near a rough surface

We study the lifetime of the excited state of an atom or molecule near a plane surface with a given random surface roughness. In particular, we discuss the impact of the scattering of surface modes within the rough surface. Our study is completed by considering the lateral correlation length of the decay rate and the variance discussing its relation to the C0 correlation

Ultra-thin titanium nitride films for refractory spectral selectivity

We demonstrate a selectively emitting optical Fabry-P\'erot resonator based on a few-nm-thin continuous metallic titanium nitride film, separated by a dielectric spacer from an optically thick titanium nitride back-reflector, which exhibits excellent stability at 1070 K against chemical degradation, thin-film instabilities and melting point depression. The structure paves the way to the design and fabrication of refractory thermal emitters using the well-established processes known from the field of multilayer and rugate optical filters. We demonstrate that a few-nanometer thick films of titanium nitride can be stable under operation at temperatures exceeding 1070 K. This type of selective emitter provides a means towards near-infrared thermal emission that could potentially be tailored to the accuracy level known from rugate optical filters.Comment: 16 pages, 6 figure

Nonlinear Dynamics of Ultrashort Long-Range Surface Plasmon Polariton Pulses in Gold Strip Waveguides

We study experimentally and theoretically nonlinear propagation of ultrashort long-range surface plasmon polaritons in gold strip waveguides. The nonlinear absorption of the plasmonic modes in the waveguides is measured with femtosecond pulses revealing a strong dependence of the third-order nonlinear susceptibility of the gold core on the pulse duration and layer thickness. A comprehensive model for the pulse duration dependence of the third-order nonlinear susceptibility is developed on the basis of the nonlinear Schrö dinger equation for plasmonic mode propagation in the waveguides. The model accounts for the intrinsic delayed (noninstantaneous) nonlinearity of free electrons of gold as well as the thickness of the gold film and is experimentally verified. The obtained results are important for the development of active plasmonic and nanophotonic component