We report the generation of square temporal-shape pulses with no loss of spectral bandwidth, using an analytic expression for the spectral phase modulation dependent only on the input spectrum and stretching factor. We demonstrate numerically and experimentally conversion of 40fs pulses into 150 times longer flat top pulses with sharp on and off fronts. Applications in pulse amplification and f...

We predict the existence of spatial-spectral vortex solitons in one-dimensional periodic waveguide arrays with quadratic nonlinear response. In such vortices the energy flow forms a closed loop through the simultaneous effects of phase gradients at the fundamental frequency and second-harmonic fields and the parametric frequency conversion between the spectral components. The linear stability a...

We theoretically and experimentally demonstrate the up-conversion fluorescence control via resonance-mediated two-photon absorption in rare-earth ions by varying both the laser polarization and phase. We show that both the laser polarization and phase can control the up-conversion fluorescence, and the up-conversion fluorescence intensity is decreased when the laser polarization changes from li...

We experimentally demonstrate quasi-phase-matched (QPM) four-wave-mixing (FWM) in silicon (Si) nanowire waveguides with sinusoidally modulated width. We perform discrete wavelength conversion over 250 nm, and observe 12 dB conversion efficiency (CE) enhancement for targeted wavelengths more than 100 nm away from the edge of the 3-dB conversion bandwidth. The QPM process in Si nanowires is rigor...

The spatial and spectral properties of entangled photons from spontaneous parametric down-conversion (SPDC) with a focused pump are investigated with theoretical analysis and numerical simulation. Here, the spatial and spectral properties of down-converted photons are fully calculated without using the transverse momentum conservation assumption. We have obtained the spatial and spectral proper...

We report the first experimental demonstration of even-order aberration cancellation in quantum interferometry. The effect is a spatial counterpart of the spectral group velocity dispersion cancellation, which is associated with spectral entanglement. It is manifested in temporal interferometry by virtue of the multiparameter spatial-spectral entanglement. Spatially entangled photons, generated...

The majority of the nonlinearity in a communication system is attributed to the power amplifier (PA) present at the final stage of the transmitter chain. In this paper, we consider Gaussian distributed input signals (such as OFDM), and PAs that can be modeled by memoryless or memory polynomials. We derive closed-form expressions of the PA output power spectral density, for an arbitrary nonlinea...

In this paper we describe theoretically quantum control of temporal correlations of entangled photons produced by collinear type II spontaneous parametric down-conversion. We examine the effect of spectral phase modulation of the signal or idler photons arriving at a 50/50 beam splitter on the temporal shape of the entangled-photon wave packet . The coincidence count rate is calculated analytic...