Inclined-incidence hard-X-ray resonator with ultrahigh efficiency and resolution

Abstract

We report a high-efficiency hard-X-ray resonator with inclined-incidence geometry. A beam incident at 36.87° with respect to [3 1 0] excites Bragg back diffraction along (12 4 0) at 14.4388 keV for resonance in a Si-based resonator to produce intense resonance fringes. The experimental results showed the visibility enhanced by nearly 30 times compared with normal incidence. Also numerical calculations of the inclined-incidence resonator demonstrate ultrahigh efficiency and extremely narrow resolving power (sub-meV) with low background. This geometry surpasses the intrinsic limits of normal-incidence crystal-based resonators and enables ultrahigh-resolution X-ray optics for X-ray diffraction, spectroscopy, and imaging applications.

Theoretical considerations in the construction of hard X-ray resonators at inclined incidence with ultra-high efficiency and resolution

“…The efficiency is thus remarkably enhanced by changing the incident path from normal to Bragg incidence. An experiment using a hard X-ray resonator at Bragg incidence was demonstrated earlier with a 200 mm (first plate)/240 mm (gap)/100 mm (second plate) Sibased cavity (Wu et al, 2015). The efficiency of the FP resonance at Bragg incidence, as measured by the visibility V = (I max À I min )/(I max + I min ), was enhanced by nearly 30 times compared with normal incidence.…”

“…Also, the efficiency (peak transmission) of the FP resonance was limited by crystal absorption. To improve the performance of crystalbased resonators, inclined-incidence resonators have been applied by utilizing one of the multiple diffractions as the incident beam to excite back reflection in the cavity for resonance, and the experimental results exhibited ultra-high efficiency compared with that at normal incidence (Wu et al, 2015).…”

Design and fabrication of silicon nanowires towards efficient solar cells

“…In contrast, the slanting SiNWs attract attentions on their special characteristics as well. Simulation works have compared the light harvesting ability between the slanting and vertically aligned SiNW structure [106][107][108]. The slanting SiNWs architecture demonstrates a strong suppression of reflectance and enhanced light trapping ability with highest ultimate efficiency of 33.45%, better than its freestanding counterparts (28.36%) [106].…”

“…For a typical vertical axial p-i-n NWs, if the nanowires are tilted from the substrate, much of the incident light can be directly absorbed by the active region without passing through the p(n) region, and thus greatly enhance the absorption of the active region and raise the efficiency. Inclined SiNWs with growth direction of <110> and <112> on <111> are simulated [108]. They showed better efficiency enhancement (4% and 3.87% respectively) than the vertical SiNWs solar cells (3.41%).…”

Planar Retro-Reflector for Grazing Incident Beam of High-Energy X-Ray Photons

“…However, such resonators require a stringent temperature control, since the crystal plates themselves are affected by thermal expansion, which, in its turn, leads to a problem of non-stability in lattice parameter of the diffracting planes ( ) [29]. The absorption, and, consequently, the crystal plate heating problem are partially solved in [23], where, instead of a conventional cavity with normal incidence, the authors of paper [23] use an inclined incident beam along one of the multiple diffraction directions to generate back diffraction in a resonator cavity. To address to change in the angle of incidence, authors remove the absorption in the first crystal, in contradiction to conventional normal-incidence one-cavity FR resonators setup.…”