Rewriting the rules governing high intensity interactions of light with matter

Abstract

The trajectory of discovery associated with the study of high-intensity nonlinear radiative interactions with matter and corresponding nonlinear modes of electromagnetic propagation through material that have been conducted over the last 50 years can be presented as a landscape in the intensity/quantum energy [I-ħω] plane. Based on an extensive series of experimental and theoretical findings, a universal zone of anomalous enhanced electromagnetic coupling, designated as the fundamental nonlinear domain, can be defined. Since the lower boundaries of this region for all atomic matter correspond to ħω ~ 10(3) eV and I ≈ 10(16) W cm(-2), it heralds a future dominated by x-ray and γ-ray studies of all phases of matter including nuclear states. The augmented strength of the interaction with materials can be generally expressed as an increase in the basic electromagnetic coupling constant in which the fine structure constant α → Z(2)α, where Z denotes the number of electrons participating in an ordered response to the driving field. Since radiative conditions strongly favoring the development of this enhanced electromagnetic coupling are readily produced in self-trapped plasma channels, the processes associated with the generation of nonlinear interactions with materials stand in natural alliance with the nonlinear mechanisms that induce confined propagation. An experimental example involving the Xe (4d(10)5s(2)5p(6)) supershell for which Z ≅ 18 that falls in the specified anomalous nonlinear domain is described. This yields an effective coupling constant of Z(2)α ≅ 2.4 > 1, a magnitude comparable to the strong interaction and a value rendering as useless conventional perturbative analyses founded on an expansion in powers of α. This enhancement can be quantitatively understood as a direct consequence of the dominant role played by coherently driven multiply-excited states in the dynamics of the coupling. It is also conclusively demonstrated by an abundance of data that the utterly peerless champion of the experimental campaign leading to the definition of the fundamental nonlinear domain was excimer laser technology. The basis of this unique role was the ability to satisfy simultaneously a triplet (ω, I, P) of conditions stating the minimal values of the frequency ω, intensity I, and the power P necessary to enable the key physical processes to be experimentally observed and controllably combined. The historical confluence of these developments creates a solid foundation for the prediction of future advances in the fundamental understanding of ultra-high power density states of matter. The atomic findings graciously generalize to the composition of a nuclear stanza expressing the accessibility of the nuclear domain. With this basis serving as the launch platform, a cadenza of three grand challenge problems representing both new materials and new interactions is presented for future solution; they are (1) the performance of an experimental probe of the properties of the vacuum state associated with the dark ener...

Generation of Intense and Temporally Clean Pulses—Contrast Issues of High-Brightness Excimer Systems

“…The straightforward way is to use a dual-wavelength system, where the generation of the high spatial and temporal quality pulse is carried out at longer wavelengths. After frequency conversion (usually frequency doubling or tripling) the shortpulse is amplified in UV gain modules [9][10][11][12][13][14][15][16], as shown in Figure 1. This approach provides a great ability to precisely control the pulse parameters and, therefore, the characteristics of the system output.…”

“…In this way, both the temporal and the spatial properties of the main pulse are reset in the "middle" of the system, prior to the amplification in the excimer amplifier chain. Hybrid strategy involving the use of a UV seed-beam produced with a femtosecond IR or visible source that subsequently undergoes amplification in excimer amplifier modules (based on [9]).…”

Status of short-pulse KrF amplifier research and development at HILL, Szeged

“…In the view of the recent progress of IR solid-state laser systems high-brightness ultraviolet (UV) excimer lasers can be regarded as complementary sources. Their main advantage occurs mainly in those experiments where high photon energy, optimum spatial concentration and/or efficient conversion of the pulse energy to radiation of even shorter wavelength are needed [1,2]. At present the maximum peak power of short-pulse excimer systems is limited to the TW level [1,2,4,5] by the difficulties associated with the construction of short-pulse UV amplifiers [1,2] and by the inherently limited energy extraction from excimer amplifiers of short energy storage time [1,3].…”

“…Their main advantage occurs mainly in those experiments where high photon energy, optimum spatial concentration and/or efficient conversion of the pulse energy to radiation of even shorter wavelength are needed [1,2]. At present the maximum peak power of short-pulse excimer systems is limited to the TW level [1,2,4,5] by the difficulties associated with the construction of short-pulse UV amplifiers [1,2] and by the inherently limited energy extraction from excimer amplifiers of short energy storage time [1,3].Excimers are ideal four-level systems allowing very efficient operation even in the UV for pulses longer than the storage (or pumping) time. However, they exhibit moderate extraction efficiency for shorter pulses, because of the relatively short (several ns) storage time compared to the accessible pumping times (several times 10 ns, or more).The saturation energy density of excimers is very low compared to solid-state systems; typically is in the range of several mJ/cm 2 .…”

“…However, they exhibit moderate extraction efficiency for shorter pulses, because of the relatively short (several ns) storage time compared to the accessible pumping times (several times 10 ns, or more).The saturation energy density of excimers is very low compared to solid-state systems; typically is in the range of several mJ/cm 2 . In KrF power amplifiers the optimum operation both for efficiency and contrast is a critical function of the energy density [1,6], which can only be maintained when the energy density is set to εopt ≈ 2.2 x εsat ≈ 4.5 mJ/cm 2 [1,2,6,7]. This condition requires large amplifier cross-sections already for moderate output energies.…”