Photonic band gap and x-ray optics in warm dense matter

Abstract

Photonic band gaps for the soft x-rays, formed in the periodic structures of solids or dense plasmas, are theoretically investigated. Optical manipulation mechanisms for the soft x-rays, which are based on these band gaps, are computationally demonstrated. The reflection and amplification of the soft x-rays, and the compression and stretching of chirped soft x-ray pulses are discussed.A scheme for lasing with atoms with two energy levels, utilizing the band gap, is also studied.

Hard X-ray or Gamma Ray source based on the two-stream instability and backward Raman scattering

“…An intense hard x-ray or gamma ray source would open up many possible commercial applications, including the atomic spectroscopy [10][11][12], the dynamical imaging of fast biological processes [13,14] and the nextgeneration semi-conductor lithography [15][16][17][18]. Yet, it is very hard to achieve intense hard x-ray or gamma ray source [6][7][8][9][19][20][21][22].…”

Forward Raman compression via photonic band gap in metals or warm dense matter

“…It is widely used to manipulate the visible lights for various practical purposes [1]. It is shown that even the soft x-ray could be manipulated using the PBG [2]. In particular, it is noted that the group velocities of the pulses could be considerably different from each other.…”

“…As discussed in Ref. [2], the band width of the pump pulse should be much smaller than the band gap, in order for a well-defined wave packet of the velocity to be considerably different from speed of * Current Address: 28 Benjamin Rush Ln., Princeton, NJ 08540 the light in vacuum. This condition imposes a constraint on the pulse duration [2] τ > 10 ω ω pe…”

“…The backward Raman scattering (BRS), which has been successful for the compression of the visible light, could make such intense x-rays even shorter and more intense in dense plasmas [6][7][8][9]. However, many physical processes to be considered for the x-ray compression in dense plasmas are different from those for visible lights in ideal plasmas, including the Fermi degeneracy [10,11], the electron quantum diffraction [12], the electron band gap [2] and the plasmon decay [13], to mention a few. These different processes render some severe difficulties in the visible light BRS become harmless in the x-ray BRS, or vice versa.…”

The energy band structures of the warm dense plasmas with micro-structures inherited from original carbon nanotubes

“…As a transient state, WDM has a density of the same order as solid, and a temperature of a few tens of thousands of kelvins (a few electronvolts), and even possibly keeps the original ionic structure unchanged. The ultra-fast laser-target and particle-beam-target experiments are giving quantitative measurements on WDM during the sudden heating of the solid targets [3][4][5][6]. With the availability of ultra-short (a few femtoseconds) extreme ultraviolet (XUV) lasers and other ultra-fast x-ray radiation sources, it is possible to ionize the electrons from a large fraction of the atoms at the focal region, producing the warm dense plasmas with the temperature of a few eVs, while keeping the original ionic structure unchanged because the ions' moving time scale is larger than a few picoseconds.…”