We present a closed-loop technique for measuring wavelength shifts associated with fiber Bragg gratings by using a fused biconical wavelength division multiplexer (WDM). The spectral response of the WDM is actively tuned by stretching of the coupling region to maintain a fixed coupling ratio at the reflected Bragg wavelength. The closed-loop operation allows sensitivities usually associated wit...

It is possible, by selective excitation of homogeneously broadened lines, to produce response signals, which are orders of magnitude narrower than the original lines. The new type of echo, which allows detecting such signals, and the formalism, useful for understanding the phenomenon, as well as the experimental examples from NMR spectroscopy are presented. Long-lived partial NMR echo in solids...

The state-covariance of a linear filter is characterized by a certain algebraic commutativity property with the state matrix of the filter, and also imposes a generalized interpolation constraint on the power spectrum of the input process. This algebraic property and the relationship between state-covariance and the power spectrum of the input allow the use of matrix pencils and analytic interp...

A scale-invariant theory is derived for the linear optical properties of nontrivial fractals (fractal clusters) in the collective region, i.e., near the center of the absorption band. A model of dilute fractals is introduced and is used to find the shape of the wings of the absorption line in the binary approximation. Strong fluctuations of the local fields in nontrivial fractals are described....

Transmission and phase-shift characteristics of dichroic high-pass filters with cutoff frequencies as high as 1.11 THz and of a cross-shaped grid bandpass filter with a resonance frequency of 280 GHz were measured with an electro-optic sampling terahertz time-domain spectrometer operating between 0.1 and 2 THz. Good agreement with transmission theories is found. We also compare the transmission...

Spatial and temporal laser pulse shaping is reported for two adjacent ranges of the spectrum. Thereto, two-photon excited fluorescence dyes measured tailored pulses having different spectral components which possess differently modulated spatial shapes. These particularly designed are formed by using a 4f-temporal liquid crystal shaper followed 2D-spatial setup. Increased contrasts between in c...

An apparatus is described which is convenient for studying the optical properties of substances with reststrahlen having wave-lengths from 6 to 150μ. A vibrationless support is described, the essential features of which are copied from the design of R. M tiller but the construction is simplified. The transmission of several gases was studied with reststrahlen having wave-lengths 20 to 33μ. S02 ...

Visual saliency detection is useful for applications like image segmentation, image retrieval et al. According to the thought that the near-infrared image can provide complementary information to the corresponding visible image, a new region based multispectral saliency detection method is proposed. The source images are decomposed into homogeneous regions by superpixel algorithm in 6-dimention...

The present work illustrates the variable viscosity of dust nanofluid runs over a permeable stretched sheet with thermal radiation. The problem has been modelled mathematically introducing the mixed convective condition and magnetic effect. Additionally analysis of entropy generation and Bejan number provides the fine points of the flow. The of model equations are transformed into non-linear or...