Abstract
The concepts of time refraction was introduced in recent years, as the temporal analogue of the usual (space) refraction, for waves propagating in non-stationary optical media. We discuss possible experimental configurations for time refraction of low intensity and short laser pulses propagating in optical fibers, and their eventual use in photonics. We generalize our previous work to the case of guided propagation. The expected frequency shifts, amplitudes and shapes of the secondary pulses resulting from time refraction are calculated.

Abstract
We derive the effects of time refraction in a dispersive medium. A new type of radiation process is described that extends the concept of Unruh radiation to a non-accelerated but superluminal perturbation of the optical properties of a medium. The case of a plasma is considered as an example.

Abstract
We experimentally observe a high-contrast intensity modulation in the multimode CW output of a Titanium:Sapphire laser, This modulation has a very low frequency (in the hundreds of Hz range), being stable and self-sustaining, unlike previously reported regimes which require external perturbations such as a periodic change in the resonant cavity length. This effect results from the nonlinear coupling of several longitudinal modes with very large frequency spacing (of the order of tens of THz) which arise due to mode competition violation (promoted by dispersion control within the laser cavity), associated with the large gain bandwidth of Ti:Sapphire, To our knowledge, this is a previously unreported phenomenon. for which we are currently developing an adequate theoretical model. These results may prove useful in the further understanding of the onset of mode-locked operation in ultrashort lasers and other highly nonlinear systems.

Abstract
We report on simulation studies of thin plasma foils explosions upon interacting with high-intensity, ultra-short laser pulses. By using a fully relativistic Particle-in-cell code we describe the time-resolved position, momentum and energy of electrons and ions, for laser pulses with durations of tens of fs and intensities ranging from 10(20) W/cm(2) to 10(23) W/cm(2). Results show the generation of a Mev electron beam as well as supra-Mev ions. Ponderomotive Boost and Colombic Explosions are mechanisms used to explain the results.

Abstract

Abstract
Can entanglement and the quantum behavior in physical systems survive at arbitrary high temperatures? In this Letter we show that this is the case for a electromagnetic field mode in an optical cavity with a movable mirror in a thermal state. We also identify two different dynamical regimes of generation of entanglement separated by a critical coupling strength.