Showing papers on "Supercontinuum published in 1991"
TL;DR: It is found that the presence of transverse spatial dynamics leaves the phase characteristics qualitatively the same as for conventional self-phase modulation, which implies that, contrary to what has recently been claimed, the red always leads the blue in the supercontinuum.
Abstract: An investigation is made of the combined effects of nonlinearity and diffraction on self-phase modulation of optical pulses propagating in dispersionless homogeneous bulk material. It is found that the presence of transverse spatial dynamics leaves the phase characteristics qualitatively the same as for conventional self-phase modulation. In particular, this implies that, contrary to what has recently been claimed, the red always leads the blue in the supercontinuum.
52 citations
TL;DR: In this article, the spectral distribution of an intense femtosecond pulse propagating in a one-dimensional Kerr medium (optical fibre) was computed numerically, and the effects of self-phase modulation, self-steepening, group velocity dispersion, higher order dispersion (β (3) term), and Raman scattering were investigated.
6 citations
TL;DR: In this paper, the application of some of the principal methods of picosecond and femtosecond laser spectroscopy to the investigation of the dynamics of carriers, phonons and surface structure in semiconductors is discussed.
Abstract: This article reviews the application of some of the principal methods of picosecond and femtosecond laser spectroscopy to the investigation of the dynamics of carriers, phonons and surface structure in semiconductors. The measurement of the temporal evolution of photoinduced luminescence, absorption, reflection and scattering in semiconductors makes it possible to obtain the lifetimes of photogenerated electrons, holes, excitons and phonons in both the bulk and quantum wells and superlattice structures. The information produced by these studies is necessary for the basic understanding of the underlying physics of semiconductors. In addition, the parameters obtained from these studies are needed for evaluating ultrafast transport, switching, photoconductive response and imaging in semiconductor materials, which will determine their limitations for use in high-speed and high-frequency devices and computers. For measuring time resolved luminescence, the principal techniques used, namely, the streak camera, the optical Kerr gate and the up-conversion gate are thoroughly discussed. Several pump and probe methods are described for the determination of time resolved absorption, reflection and Raman scattering. For absorption measurements where the probe wavelength differs from the pump, the former is generated in nonlinear media by means of stimulated Raman scattering and the supercontinuum for the UV and visible regions and by parametric and difference frequency generation for the near- and mid-IR. Nonlinear optics techniques considered are degenerate and nondegenerate four-wave mixing and transient grattings among which photon echoes yield the momentum relaxation of hot electrons. Coherent anti-Stokes Raman scattering (CARS) and phase conjugate Raman scattering (PC) are described to determine phonon dephasing times and the nonlinear susceptibility, χ3.
6 citations
TL;DR: In this paper, the authors predict a strong transient Raman gain stimulated by a Gaussian noise field in dispersive media, based on the method of successive approximations, the first of which is the Markovian approximation.
Abstract: We predict a strong transient Raman gain stimulated by a Gaussian noise field in dispersive media. Our theory is based on the method of successive approximations, the first of which is the Markovian approximation. It is shown that the transient behavior will take place near critical pump intensity both for “short” ( τ p > T 2 ) and “ultrashort” ( τ p T 2 ) laser pulses (τ p is the pump pulse duration, T 2 is the relaxation time of optical phonons). Solutions for average intensities of the Stokes wave and optical phonons are obtained for arbitrary form of the given pump pulse. We show that transient Raman gain allows to form a very steep leading edge of the Stokes pulse. The steady-state increments of the second approximation describe the effects of a strong noise field. We show that after the intensity of the pump has exceeded a value beyond which the framework of validity of the Markovian approximation does not hold anymore, the steady-state Raman gain is saturated. We give a review of experimental results and make estimations for conditions of observing transient scattering in the field of a noise pump. Methods of obtaining the powerful femtosecond pulses based on stimulated Raman scattering of broad-band excimer lasers and supercontinuum emission are suggested.