Interference (wave propagation)

About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.

Method and apparatus for the rapid acquisition of data in coherence scanning interferometry

Abstract: A method of profiling a rough surface of an object includes the steps of producing an interference pattern of the object surface (14) using an interferometer (1) to produce an illumination intensity on the pixels of an imaging device (18), varying the optical path difference between the object surface (14) and a reference surface (22) of the interferometer (1) through a range including a position of zero optical path difference for each pixel, calculating values of an interference discriminator function to identify the regions of coherence, gathering at the imaging device (18) and storing for each pixel a plurality of intensity values about the region of coherence - as identified by the state or value of the interference discriminator function calculations - at consecutive data points spaced along the range by a predetermined phase difference, storing for each pixel the relative position of the plurality of intensity values along the range, and calculating from the stored intensity values the difference in height between two selected pixels using methods known in the art. An apparatus for practising the invention is also disclosed.

All-fiber three-path Mach-Zehnder interferometer

Abstract: We report the realization of a three-path Mach-Zehnder interferometer using single-mode fibers and two integrated 3 x 3 fiber couplers. We observed enhanced phase sensitivity, as compared with two-path interferometers, with a visibility of the interference pattern of more than 97%. This interferometer has an analog in two-photon interferometry, and we believe it to be the first nontrivial example of N x N multiport interferometers.

Wave propagation through disordered media without backscattering and intensity variations

Abstract: A fundamental manifestation of wave scattering in a disordered medium is the highly complex intensity pattern the waves acquire due to multi-path interference. Here we show that these intensity variations can be entirely suppressed by adding disorder-specific gain and loss components to the medium. The resulting constant-intensity waves in such non-Hermitian scattering landscapes are free of any backscattering and feature perfect transmission through the disorder. An experimental demonstration of these unique wave states is envisioned based on spatially modulated pump beams that can flexibly control the gain and loss components in an active medium. Constant-intensity waves that can travel through a disordered medium without being scattered or reflected are being theoretically predicted. The analysis of Konstantinos Makris of the University of Crete, Greece, and co-workers from Austria and the United States suggests that such constant-intensity waves can form in a general disordered medium provided a suitable distribution of the imaginary part of the medium’s refractive index is achieved by spatially varying the gain and loss of the medium appropriately. In other words, adding a judiciously selected gain-and-loss distribution to a disordered medium causes waves to lose all of their internal intensity variations so that they travel through the disorder without being back-reflected. This behaviour should be experimentally confirmable by spatially modulating the pump beams in an active medium to create the desired gain-loss profile.

Diversity Loss due to Interference Correlation

Abstract: Interference in wireless systems is both temporally and spatially correlated. Yet very little research has analyzed the effect of such correlation. Here we focus on its impact on the diversity in Poisson networks with multi-antenna receivers. Most work on multi-antenna communication does not consider interference, and if it is included, it is assumed independent across the receive antennas. Here we show that interference correlation significantly reduces the probability of successful reception over SIMO links. The diversity loss is quantified via the diversity polynomial. For the two-antenna case, we provide the complete joint SIR distribution.

Polarization entanglement-enabled quantum holography

Abstract: Holography is a cornerstone characterization and imaging technique that can be applied to the full electromagnetic spectrum, from X-rays to radio waves or even particles such as neutrons. The key property in all these holographic approaches is coherence, which is required to extract the phase information through interference with a reference beam. Without this, holography is not possible. Here we introduce a holographic imaging approach that operates on first-order incoherent and unpolarized beams, so that no phase information can be extracted from a classical interference measurement. Instead, the holographic information is encoded in the second-order coherence of entangled states of light. Using spatial-polarization hyper-entangled photon pairs, we remotely reconstruct phase images of complex objects. Information is encoded into the polarization degree of the entangled state, allowing us to image through dynamic phase disorder and even in the presence of strong classical noise, with enhanced spatial resolution compared with classical coherent holographic systems. Beyond imaging, quantum holography quantifies hyper-entanglement distributed over 104 modes via a spatially resolved Clauser–Horne–Shimony–Holt inequality measurement, with applications in quantum state characterization. By exploiting polarization entanglement between photons, quantum holography can circumvent the need for first-order coherence that is vital to classical holography.