Topic
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.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this article, an optical set-up based on the combination of new CCD technology, a ruby laser and a Mach-Zehnder shear interferometer is presented for defect detection in composites.
60 citations
••
TL;DR: In this article, a reconfigurable quantum frequency processor is proposed to perform arbitrary manipulations of spectrally encoded qubits in the quantum internet, achieving high-fidelity flips of spectral correlations on two entangled photons.
Abstract: Quantum information is the next frontier in information science, promising unconditionally secure communications, enhanced channel capacities, and computing capabilities far beyond their classical counterparts. And as quantum information processing devices continue to transition from the lab to the field, the demand for the foundational infrastructure connecting them with each other and their users---the quantum internet---will only increase. Due to the remarkable success of frequency multiplexing and control in the classical internet, quantum information encoding in optical frequency offers an intriguing synergy with state-of-the-art fiber-optic networks. Yet coherent quantum frequency operations prove extremely challenging, due to the difficulties in mixing frequencies efficiently, arbitrarily, in parallel, and with low noise. Here we implement an original approach based on a reconfigurable quantum frequency processor, designed to perform arbitrary manipulations of spectrally encoded qubits. This processor's unique tunability allows us to demonstrate frequency-bin Hong-Ou-Mandel interference with record-high 94% visibility. Furthermore, by incorporating such tunability with our method's natural parallelizability, we synthesize independent quantum frequency gates in the same device, realizing the first high-fidelity flip of spectral correlations on two entangled photons. Compared to quantum frequency mixing approaches based on nonlinear optics, our linear method removes the need for additional pump fields and significantly reduces background noise. Our results demonstrate multiple functionalities in parallel in a single platform, representing a huge step forward for the frequency-multiplexed quantum internet.
60 citations
••
TL;DR: In this paper, a stochastic description of the amplitude fluctuation using probability density functions and calculated amplitude fluctuations with M integrations when reduction techniques are applied was provided. But the amplitude fluctuations were not considered in this paper.
Abstract: The dynamic range of optical time-domain reflectometry (OTDR) can be extended by employing self-heterodyne coherent detection. However, with coherent detection OTDR (C-OTDR) there is a problem of amplitude fluctuation in the C-OTDR trace caused by (1) the fading noise resulting from the interference between the Rayleigh backscattered lights, (2) the polarization dependent fluctuation of the optical detection efficiency, and (3) the heterodyne detection efficiency fluctuation due to the relative phase change between the Rayleigh backscattered signals and the local oscillator (LO). This paper provides a stochastic description of the amplitude fluctuation using probability density functions and the calculated amplitude fluctuation with M integrations when reduction techniques are applied. We have found theoretically that it is difficult to reduce the amplitude fluctuation effectively by the optical frequency domain integration technique using the asynchronous optical frequency hopping of the source. This is because of an inclination increase in the C-OTDR trace which reduces the measurement accuracy. We propose a synchronous optical frequency hopping technique in which an RF current pulse is induced in the drive current of the laser diode (LD) during the LD temperature change. This effectively reduces the amplitude fluctuation without any increase in the inclination. The amplitude fluctuation for a 1 /spl mu/s pulse width is reduced experimentally to 1/7 that with the LD temperature stabilized. For 100 and 30 ns pulse widths, it is reduced to 1/11 of that with the LD temperature stabilized. These experimental results are in good agreement with the calculated ones.
60 citations
•
13 Oct 2005TL;DR: In this paper, a water-filling procedure was proposed to determine a power level to be used by the transmitter to transmit data at a target data rate under a constraint of an interference limit, the interference limit constraint constraining the transmit power level plus an interference level collectively produced by a set of transmitters from the plurality of the transmitters.
Abstract: There is disclosed a method for controlling transmit power in a multi-user cognitive radio environment having a plurality of transmitters, the method comprising: identifying one or more spectrum holes in a frequency band; identifying a spectrum hole for use by a transmitter; and applying a water-filling procedure to determine a transmit power level to be used by the transmitter to transmit data at a target data rate under a constraint of an interference limit, the interference limit constraint constraining the transmit power level plus an interference level collectively produced by a set of transmitters from the plurality of transmitters to be less than the interference limit.
60 citations
•
03 Jun 1998TL;DR: In this paper, two optical gratings are used to produce a spatial displacement in an interference field of two different diffraction components produced by one grating from different components generated by another grating, and the curvature of the surface can be determined.
Abstract: A system and method for determining a curvature of a specularly reflective surface based on optical interference. Two optical gratings are used to produce a spatial displacement in an interference field of two different diffraction components produced by one grating from different diffraction components produced by another grating. Thus, the curvature of the surface can be determined.
60 citations