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F Raineri

Publications and source records attributed to F Raineri.

7 recordsLinked to original sources
PubMed2006

Fast thermo-optical excitability in a two-dimensional photonic crystal.

We experimentally demonstrate excitability in a semiconductor two-dimensional photonic crystal. Excitability is a nonlinear dynamical mechanism underlying pulselike responses to small perturbations in systems possessing one stable state. We show that a band-edge photonic crystal resonator exhibits class II excitability, resulting from the nonlinear coupling between the high-Q optical mode, the charge-carrier density, and the fast (sub-micros) thermal dynamics. In this context, the critical slowing down of the electro-optical dynamics close to the excitable threshold can delay the optical response by an amount comparable to the duration of the output pulse (5 ns). The latter results from a short thermal dynamical excursion along a high local intensity manifold of the phase space.

Arsenicals↗
PubMed2006

Nonadiabatic dynamics of the electromagnetic field and charge carriers in high-Q photonic crystal resonators.

We address, both experimentally and theoretically, phase and amplitude dynamics of the electromagnetic field in a two-dimensional photonic crystal when femtosecond pulses are injected. We demonstrate that the usual adiabatic approximation underlying the dynamics of field and carriers in a semiconductor resonator is no longer valid, since in general the photon lifetime cannot be neglected with respect to the carrier recombination lifetime. Parameter regions where adiabaticity is broken are shown, and the ubiquity of the observed dynamical scenario in the new generation of active photonic microresonators is predicted.

Journal Article↗
PubMed2005

Tuning a two-dimensional photonic crystal resonance via optical carrier injection.

We report on wide wavelength tuning through optical injection of carriers of a photonic resonance observed in reflectivity at 1543 nm in an InP-based two-dimensional photonic crystal slab. An 8-nm blueshift, which represents 20 times the resonance linewidth, is observed when a 4-kW/cm2 intense optical pump is incident on the sample. An analytical model that we developed, based on a coupled-mode nonlinear approach, allows us to describe this phenomenon in detail.

Journal Article↗
PubMed2003

Second-harmonic generation in one-dimensional photonic edge waveguides.

Diffraction losses in one-dimensional photonic crystal (PC) waveguides are the primary limitation on second-harmonic (SH) conversion efficiency. By using a finite difference time domain (FDTD) code taking into account second-order nonlinear polarization, we investigated these losses numerically, particularly at the SH wavelength. We propose an efficient SH conversion scheme in Al(x)Ga(1-x)As/air-etched waveguides. An analytical model is used to extrapolate the conversion efficiency to a number of periods for which time consumption makes the FDTD codes unsuitable.

Journal Article↗
PubMed2002

A shared care approach to the management of erectile dysfunction in the community.

Erectile dysfunction (ED) affects men of all ages and results in considerable distress and impact on quality of life for those who suffer from it. As ED is associated with a wide variety of under-lying conditions and cardiovascular co-morbidities, there is a requirement for diversity of treatment options and several factors must be considered to customise and optimise therapy. In the ideal holistic approach to management of the ED patient, both primary care and specialist physicians have an important role to play. This article reports on a sequential approach for the diagnosis and treatment of ED, with an emphasis on 'shared care'. The deliberations are based on a pan-European inter-disciplinary group that met at the Lygon Arms, UK on 22 February 2002.

Erectile Dysfunction↗
PubMed1999

A severe, late reaction to radiological contrast media mimicking a sepsis syndrome.

An unusual, severe delayed reaction to non-ionic intravenous contrast media was observed. A 44-year-old man underwent a computed tomography scan with non-ionic contrast media. Four hours later the patient collapsed with hypotension and cardiovascular shock. Aggressive management (including inotropic support and fluid resuscitation) was instituted in the intensive care unit. Rigorous imaging and biochemical and microbiological investigation failed to identify a source of this man's circulatory collapse. A rapid recovery ensued and at 3 months follow-up the patient was suffering no residual effects from this event. To our knowledge, this is only the second report of a severe delayed reaction to radiological contrast media and the first that manifested as a prolonged hypotensive syndrome.

Adult↗