Existence of a Photonic Band Gap and Underlying Physical Processes

Abstract

Mechanisms of the overlapping of gaps due to a refractive index difference minimum and Anderson localization for photonic band gap (PBG) have been used and they give a refractive index contrast difference of less than two percent for X-, L-, and W-points of the Brillouin zone for the pseudogap. Another physical process for the existence of PBG is the use of scattering strength (ε r ≥ 1) for fcc lattice structure. We have found refractive index contrast in the range 2.41–14.21 for the existence of the complete photonic band gap for bound photons (ε r ≥ 1). The lowest limit to yield a gap is 2.41 for valence photons (ε r = 1) at volume filling fraction 85.5% for spherical air atoms and at 14.5% for dielectric spheres. This work is reported for the first time and it is useful for maintaining connectivity and for easier fabrication of photonic crystals.

Revisiting the parametrization of equation of state of dark energy via SNIa data

“…There exist plenty of parametrizations for the equation of state w ( a ) (Johri 2004; Johri & Rath 2006, 2007) where a = (1 + z ) −1 , but most of them are purely phenomenological. May be, we should consider some of them in the sense that they are generalized from the behaviour of physically motivated sets of models (Linder 2008).…”

“…Unquestionably, the way we parametrize the equation of state is bound to affect our ability to extract information from the data. There are many different parametrizations have been introduced based on simplicity and the requirement of regular asymptotic behaviours (Johri 2004; Johri & Rath 2006, 2007). However, will these choices of parametrizations give us maximum power to extract information from the data?…”

Tilted Bulk Dusty Universe

“…Banerjee et al [14] have investigated Bianchi-I cosmological models consistency of a fluid with both bulk and shear viscosity. The effect of bulk viscosity on the cosmological evolution has been investigated by a number of authors in framework of general theory of relativity (Padmanabhan and Chitre [15]; Johri and Sudarshan [16]; Maartens [17]; Zimdahl [18]; Kalyani and Singh [19]; Singh, Beesham and Mbokazi [20]. Motivated by these studies,in this paper, we have investigated Bianchi type I tilted dust fluid cosmological model in the presence and absence of bulk viscosity.…”

Tilted Bulk Disordered Distribution Cosmological Model

“…Johri and Sudarshan [10]; Maartens [11]; Zimdahl [12]; Kalyani and Singh [13]; Singh, Beesham and Mbokazi [14].These motivate to study cosmological model with bulk viscosity.…”