Bragg-like interference in one-dimensional double-period quasicrystals

Abstract

Three quasi-Bragg conditions (QBCs) in one-dimensional double-period quasicrystals based on high reflectance from interference are proposed. Analytical formulas for these QBCs are derived using band-edge equations. All of these QBCs have conditions that are different from that of the traditional Bragg condition. The QBC at quarter-wave thickness in double-period quasicrystals is also discontinuous in different regions of the gap map. In contrast, the traditional Bragg condition for periodic cases, which lies at quarter-wave thickness, is continuous in different regions of the gap map. It is found that there are three thickness conditions with the maximum reflectance occurring in the midpoints of the QBCs in double-periodic quasicrystals, which is analogous to the quarter-wave thickness in traditional periodic crystals. These QBCs in double-period cases are different not only from the traditional Bragg condition in periodic cases, but also from those in Fibonacci and Thue-Morse quasicrystals.

Optical properties of periodic, quasi-periodic, and disordered one-dimensional photonic structures

“…In' the' last' years' many' researchers' have' reported' various' works' on' the' light' propagation' through'photonic'structures. 'Photonic'structures'can'be'grouped'in'three'sets,'depending'on' their' crystallographic' properties:' i)' a' periodic' spatial' modulation' of' the' dielectric' constant' gives' rise' to' a' photonic' crystal' [1][2][3][4][5][6][7][8][9];' a' modulation' of' the' dielectric' constant' that' follows' a' deterministic' generation' rule' results' in' a' photonic' quasicrystal' [10][11][12][13][14][15][16][17][18][19];' a' random' modulation' of' the' dielectric' constant' gives' rise' to' a' disordered' photonic' structure' [20,21].'' Myriads' of' possible' applications' arise' for' the' three' different' structures,' such' ,' as' photonic' crystal'lasers' [22,23]'and'quasicrystal'lasers' [24,25],'optical'fibers' [26,27],'and'sensors' [28][29][30],' when' concerning' photonic' crystals' and' quasicrystals.'…”

Enhancement of thermal spin transfer torque by double-barrier magnetic tunnel junctions with a nonmagnetic metal spacer

“…The most common structure for an MTJ is a single barrier structure. However, multi-barrier structures are considered important because of the resonant tunneling effects that occur in such structures, leading to several interesting new applications [19][20][21][22]. Therefore, some authors have investigated the magnetic properties in multi-barrier MTJs, such as the tunnel magnetoresistance (TMR) effect [23][24][25] and current-induced STT effect [26].…”