Large-scale spectral bandwidth compression by complex electro-optic temporal phase modulation

Spectral-temporal shaping of quantum light has important applications in quantum communications and photonic quantum information processing. Electro-optic temporal lenses have recently been recognized as a tool for noise-free, efficient spectral bandwidth manipulation of single-photon wavepackets. However, standard electro-optic time lenses based on single-tone modulation exhibit limited bandwidth manipulation due to material limitations on phase modulation amplitude. Here we numerically investigate the use of complex electro-optic temporal phase modulation patterns for bandwidth compression of light over multiple orders of magnitude and show the feasibility of their use in photonic interfaces for quantum network applications

Modulation of Localized States in Electroconvection

We report on the effects of temporal modulation of the driving force on a particular class of localized states, known as worms, that have been observed in electroconvection in nematic liquid crystals. The worms consist of the superposition of traveling waves and have been observed to have unique, small widths, but to vary in length. The transition from the pure conduction state to worms occurs via a backward bifurcation. A possible explanation of the formation of the worms has been given in terms of coupled amplitude equations. Because the worms consist of the superposition of traveling waves, temporal modulation of the control parameter is a useful probe of the dynamics of the system. We observe that temporal modulation increases the average length of the worms and stabilizes worms below the transition point in the absence of modulation.Comment: 4 pages, 4 figure

Temporal Aperture Modulation

The two types of modulation techniques useful to X-ray imaging are reviewed. The use of optimum coded temporal aperature modulation is shown, in certain cases, to offer an advantage over a spatial aperture modulator. Example applications of a diffuse anisotropic X-ray background experiment and a wide field of view hard X-ray imager are discussed

Nonlocal Modulation of Entangled Photons

We consider ramifications of the use of high speed light modulators to questions of correlation and measurement of time-energy entangled photons. Using phase modulators, we find that temporal modulation of one photon of an entangled pair, as measured by correlation in the frequency domain, may be negated or enhanced by modulation of the second photon. Using amplitude modulators we describe a Fourier technique for measurement of biphoton wave functions with slow detectors

Nonreciprocal Metasurface with Space-Time Phase Modulation

Creating materials with time-variant properties is critical for breaking reciprocity that imposes fundamental limitations to wave propagation. However, it is challenging to realize efficient and ultrafast temporal modulation in a photonic system. Here, leveraging both spatial and temporal phase manipulation offered by an ultrathin nonlinear metasurface, we experimentally demonstrated nonreciprocal light reflection at wavelengths around 860 nm. The metasurface, with traveling-wave modulation upon nonlinear Kerr building blocks, creates spatial phase gradient and multi-terahertz temporal phase wobbling, which leads to unidirectional photonic transitions in both momentum and energy spaces. We observed completely asymmetric reflections in forward and backward light propagations within a sub-wavelength interaction length of 150 nm. Our approach pointed out a potential means for creating miniaturized and integratable nonreciprocal optical components.Comment: 25 pages, 5 figure

Smoothed Temporal Variance Spectrum: weak line profile variations and NRP diagnostics

We describe the version of the Temporal Variance Spectrum (TVS, Fullerton, Gies & Bolton 1996) method with pre-smoothed line profile (smoothed Temporal Variance Spectrum, smTVS). This method introduced by Kholtygin et al. (2003) can be used to detect the ultra weak variations of the line profile even for very noisy stellar spectra. We also describe how to estimate the mode of the non-radial pulsations (NRP) using the TVS and smTVS with different time spans. The influence of the rotational modulation of the line profile on the TVS is considered. The analysis of the contribution of NRP and rotational modulation in the global TVS is studied.Comment: 15 pages, 21 figures, accepted for publication in MNRA