Resonant light scattering by optical solitons

We consider the process of light scattering by optical solitons in a planar waveguide with homogeneous and inhomogeneous refractive index cores. We observe resonant reflection (Fano resonances) as well as resonant transmission of light by optical solitons. All resonant effects can be controlled in experiment by changing the soliton intensity.     

Resonant quasi-resonant solitons

Propagation of an optical pulse in a set of transitions created by simple Zeeman splitting is investigated. It is shown that resonant and nonresonant circularly polarized components repel one another, while a coupled soliton state can be formed only between quasi-resonant components whose planes of polarization rotate in opposite directions.     

Resonant control of solitons

It is shown that the effect of “scattering on resonance” can be used to control envelope solitons in the driven nonlinear Schrödinger equation. The control occurs by the frequency modulated driving with multiple crossing of the resonant frequency of the soliton.     

Resonant Raman scattering in germanium

We have studied the spectral dependence of the first order Raman scattering cross section of Ge at room and liquid nitrogen temperatures in the energy region containing the E₁ and E₁ + Δ₁ optical gaps. This region was covered by a fine mesh of points obtained from the discrete lines of three gas lasers and a cw continuously tunable dye laser. Only one resonant peak was observed, as opposed to the two peaks that characterise the absorption and reflection spectra in this region. The shape of this resonance peak can be explained as due to the changes in the electronic polarizability produced by phonon-induced wave function mixing of the spin-orbit split Λ valence band doublet. The observed temperature shift in the resonant energy is much smaller than the one predicted from the known shifts of the optical gaps with temperature. Furthermore the resonant peak at room temperature appears shifted to higher energies when compared with the theoretical peak calculated from the room temperature optical constants. The resonant Raman peak appears to shift with increasing temperature by the full thermal expansion effect plus only a fraction of the electron-phonon interaction shift seen in the optical constants.     

Resonant and nonresonant optical solitons: Similarities and differences

An analysis of the similarities and differences between resonant and nonresonant optical solitons is conducted. The study focuses on physical aspects of the problem, including self-focusing and self-defocusing. Attention is given to possible applications of both types of solitons in optical information transmission and processing systems.     

Resonant interband scattering of image-potential states

Image-potential states in front of a clean Cu (100) surface were investigated by time- and angle-resolved two-photon photo-emission (2PPE). We observe a previously unknown quasi-elastic relaxation channel, which efficiently couples states with different quantum numbers, n, and parallel momenta, k_∥. This process of resonant interband scattering (RIS) is independent of sample temperature and shows a close relationship to the pure dephasing of image-potential states. Received: 1 October 2001 / Revised version: 24 October 2001 / Published online: 23 November 2001     

Resonant rayleigh scattering in semiconductor structures

Il Nuovo Cimento D - A detailed study of the relative role played by localized and/or propagating intermediate excitonic states in, resonant Rayleigh scattering (RRS) is presented for a large set...     

Resonant Bhabha scattering at MeV energies

We discuss, on a phenomenological level, the possible appearance of resonances ine ⁺+e ^? scattering at energies in the MeV region. The expected resonance cross section and angular distribution are examined. The observability depends crucially on the attainable energy resolution which is limit by the momentum distribution of the electrons contained in the target.     

Resonant multiphonon Raman scattering in AgBr

Resonant Raman scattering in AgBr single crystals is studied at low temperatures. Excitation in resonance with the indirectΓ — L exciton as intermediate state gives rise to selectively enhanced narrow two-phonon Raman scattering. The phonons involved are pairs ofLA andTO phonons of opposite wavevectors near theL-point. A simple model involving one discrete exciton level is developed to explain the resonance behaviour. The temperature dependence of the scattered intensity, that is studied for 1.8 K <T < 35 K, can consistently be interpreted within this model as being due to the lifetime of the intermediate state. Assuming that the excitons predominantly decay by one-phonon scattering with long wavelength acoustical phonons the predicted temperature dependence of the intensity is found in good agreement with the experimental result. Additional scattering peaks are believed to be due to third-order processes involving an acousticalX-phonon in addition to theL-phonons of the second-order scattering. Using an oriented sample the resonant Raman peaks are found to be polarized.     

Energy of scattering solitons in the Ward model

We present the results derived in our paper [Proc. Royal. Soc. Lond. A 461 (2005) 1965], where we have shown that the energy density of a scattering-soliton solution in Ward's integrable chiral model is the same as the energy density of a static multi-lump solution of the ℂP ³ sigma model. This explains the quantization of the total energy in the Ward model. Presented at the International Colloquium “Integrable Systems and Quantum Symmetries”, Prague, 16–18 June 2005.     

Resonant solitons in semiconductors: Transparency induced by exciton-exciton interactions

Propagation of femtosecond light pulses spectrally centered at the 1s-exciton resonance in a semiconductor is studied analytically and numerically. Soliton-like propagation is demonstrated for pulses with the input area exceeding a certain threshold. This phenomenon is shown to be different from the self-induced transparency in atomic systems and associated with the formation of the resonant solitons due to exciton-exciton interactions.     

Resonant Brillouin scattering from ZnO and CdS

Measurements are reported of the dispersion of the Brillouin scattering from acousto-electric domains in ZnO and CdS, at wavelengths close to the absorption edge. Cancellation and enhancement of the scattering was observed in both materials.     

Resonant X-ray magnetic scattering has gone soft

The Linac Coherent Light Source [1] (LCLS) at SLAC National Accelerator Laboratory is preparing for the arrival of its first scientific users in the fall of 2009. LCLS is the world's first free-electron in the spectral range 800?8,000?eV, producing intense, sub-picosecond pulses of Xrays with very high spatial coherence. The accelerator facility has been commissioned in stages, beginning in April 2007 [2] with the injector linac and culminating in December 2008 [3] with the first transport of electrons through the complete beam path. On April 10, 2009, the LCLS Project team was rewarded for years of planning, design, construction, and checkout with a dream-come-true: as undulators were placed on the beam path one-by-one, the laser simply turned on without drama in the course of one hour [4]. First visible evidence of light amplification at 8,000?eV was observed on a fluorescent screen with ten undulators in place, at which point a highly collimated spot of X-rays could be discerned in the center of the spontaneous radiation pattern. After just four days of further checkout, the intensity of this spot increased smoothly and exponentially to the threshold of “saturation” at full power with just 20 of 33 undulators in place. The commissioning team was faced with a mixture of shock and euphoria. The Project team has spent years focused on everything that could possibly go wrong, and what to do about each concern. Speaking for myself, I found I was mentally unprepared for the special case of NOTHING going wrong! In fact, a critical aspect of the FEL performance was significantly better than design goals—the gain length (the distance the electron beam must travel in undulators to increase X-ray power by a factor e) proved to be just 3.5 meters. With this gain length, and room for 33 undulators in the tunnel, we find we have ten more spares! The shutter was closed at about midnight, temporarily preventing the electron beam entering the undulator. At 8:00 A.M. the next morning, the shutter was retracted to reveal the FEL producing an 8,000?eV laser beam without need for operator intervention.     

Resonant absorption and scattering in evanescent fields

Received: 14 July 1998