Stationary light

The main purpose of this paper is to consider a two-dimensional non-stationary (2D-I-T) problem of a nonlinear waveguide excitation by a non-stationary light beam and to study spatiotemporal phenomena arising upon propagation of the beam in a step-index waveguide, first, in the quasi-static approximation and, second, with account of MD and SS effects. 

The theoretical approach is based on the solution to the mixed type linear/nonlinear generalized Schrodinger equation for spatiotemporal envelope of electrical field with account of transverse spatial derivatives and the transverse profile of refractive index. In the quasi-static approximation, this equation is reduced to the linear/nonlinear Schrodinger equation for spatiotemporal pulse envelope with temporal coordinate given as a parameter. Then the excitation problem can be formulated for a set of stationary light beams with initial amplitude distribution corresponding to temporal envelope of the initial pulse. 

Propagation of non-stationary light beam in a nonlinear medium with material dispersion is described by the scalar wave equation for the linearly-polarized y-component of electrical field E x,z,t) ... 

In the problem of pulse diffraction on waveguide junctions, the quasistatic approximation is feasible if the diffraction length of the light beam is much shorter than the characteristic length of the pulse variation owing to the mentioned above MD, FTNR and SS effects which influence the pulse envelope. Then the results obtained for stationary light beam can be used in the analysis of the non-stationary beam self-focusing. 

In this section, a problem of nonlinear waveguide excitation by stationary light beam has been investigated. In the analysis, an approach traditional for nonlinear optics and based on solution to nonlinear paraxial wave equation has been used. The range of light beam powers that induce nonlinear variation of refractive index comparable with linear contrast of the step-index waveguide has been considered. 

Thus, in the quasi-static approximation, the length of the unsteady-state regime in the core of the nonlinear waveguide is finite, as in the case of the stationary light beam propagation (see Fig. 10, 11). 

In general, as the variation of the temporal profile of the non-stationary light beam due to the SS effect or the second-order GVD effect is continuous, emission of radiation field from the guiding region is also continuous upon propagation of the pulse. This emission prevents formation of a spatiotemporal soliton in the step-index guiding structures. 

It is important to note that feasibility of the numerical technique used in this work is limited. In addition to limitations discussed in Sections 2, 3 it has been proved that sharp variations in temporal and spatial profiles of the non-stationary light beam cannot be simulated in the frames of the paraxial approach. That is why the method of modeling presented here can be applied to pulse durations greater than 10 fs. 

In this paper, spatiotemporal dynamics of non-stationary light beam propagating through the junctions of step-index nonlinear waveguides have been investigated. 

EL does not differ from that in stationary light emission observed from the same films. 

Figure 2.21 shows a schematic of the setup for simultaneous measurement of the stationary light-induced excess minority carrier microwave reflectivity and the photocurrent at the semiconductor-electrolyte contact. The sample is illuminated from the front side and photoelectrochemistry is performed using the standard... 

Figure 2.21 Experimental arrangement for simultaneous in situ stationary light-induced excess microwave reflectivity and photocurrent measurements LD, laser diode (A = 830nm) L, collimating lens C, chopper...

So, the characteristic life times of a radical, which are registered by EPR-spectroscopy in situ at the end of a polymerization process, greatly exceed the characteristic times of the stationary light and non-stationary dark proce.sses thus, they do not cause polymerization and represent radicals of the third type. The difference between spectra of radicals trapped into the polymeric matrix (9 lines of the spectrum), which were observed under the EPR-spectroscopic investigations of the methylmethacrylate samples at the... 

Here Wn,o is the starting post-polymerization rate determined using equation (4.35) at the end of a stationary light period in which Vjm = Vjmo <5 is a parameter characterizing the relative contribution of the secondary chain to the total kinetics in the interface layer and is determined by the expression... 

Furthermore, this model gives an explanation of the increase in radical concentration in the non-stationary light process coming into the solid polymeric matrix at the expense of the frozen radicals of the and R,. type. 

Stationary light generation using a perfect SW grating... 

In this subsection, we will study the propagation dynamics of a probe pulse incident upon a sample of ultracold Rb atoms dressed by a time-modulated SW coupling, and pay special attention to the stationary light generation during the process where the two coupling components are switched on and off as in Fig. 13. In Fig. 14, we focus on and together with... 

Lin YW, Liao WT, Peters T et al. Stationary light pulses in cold atomic media and without Bragg gratings. Physical Review Letters 2009 May 28 102(21) 213601(4). 

Zimmer FE, Andre A, Lukin MD and et al. Coherent control of stationary light pulses. Optics Communications 2006 Aug 15 264(2) 441-453. 

Zimmer FE, Otterbach J, Unanyan RG et al. Dark-state polaritons for multicomponent and stationary light fields. Physical Revew A 2008 Jun 16 77(6) 063823(6). 

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