Hartman effect in two Bragg gratings systems We now consider the system that was taken in [10] as thought to support the idea of a generalized Hartman effect: the double selleck chemicals Bragg gratings (DBG). Independent of the approximate method used in that paper, we find that assuming sin(k B a)=0 (the only way to obtain the reduced expressions of Table 1 in [10]) and still considering a as a variable are incongruous. Moreover, the idea that the PT becomes independent of a is incompatible with the Equation (4b) in their work, where a linear dependence on a

is reported. In the DBG, the gratings of length L o and refractive index n(z)=n 0+n 1 cos(2k B z) are separated by a distance a. The values of a considered in the experiment are indicated by arrows in Figure 6. The BG wave equation (10) Figure 6 The phase time as a function of the Bragg gratings separation. (a)

The phase time as a function of the separation a between two Bragg gratings, for incident λ=1,542 nm, k B=6.1074/μm, n 0=1.452, n 1/n 0=1.8×10−4, and L o=8.5 mm. (b, c) The PT is plotted as a function of ω, for www.selleckchem.com/products/bay80-6946.html a=42 mm. The phase time in (b) is the same as that in (c) but plotted from 0 to 10 ns to compare with Figure 2 in [10]. Arrows indicate the as in [10]. when ignoring the (n 1/n 0)2 term for n 1/n 0≪1 (as in [10]), becomes the Mathieu equation, in which Cediranib (AZD2171) solutions ψ 1(z)=Se(u,v;k B z+Π/2) and ψ 2(z)=So(u,v;k B z+Π/2) are Mathieu functions [19] with and . The real and imaginary parts of the (1,1) element of the transfer matrix are (11) with W the

Wronskian and (12) Here θ 1=θ(L o ,0), θ 2=θ(2L o +a,L o +a) analogously for χ 1,2, μ 1,2, ν 1,2, with (13) Using parameters of Longhi et al. [10] for n 0,n 1, k B, and L o , the non-resonant gap becomes resonant as the gratings separation increases. Though details are beyond the Ricolinostat purpose of this paper, we plot in Figure 6 the PT as a function of the separation a for incident-field wavelength λ=1542 nm, and as a function of the frequency ω, for a=42 mm. Recall that in [10], λ≃1,550 nm was considered. While the PT appears completely in graph (c), in (b) it is plotted in a different range to compare with the experiment. The resonant behavior of the PT with a and the absence of any generalized Hartman effect are evident. Similar results are obtained when λ=2Π/k B . Conclusion We have shown that the presumption of generalized Hartman effect for tunneling of particles and transmission of electromagnetic waves is not correct. Acknowledgements The authors would like to thank Professor Norman H. March for comments and suggestions on the manuscript. References 1. Hartman TE: Tunneling of a wave packet. J Appl Phys 1962, 33:3427.CrossRef 2.