researchers because these media can support negative reflection and refraction.
That is; when a perfect electric conductor (PEC) interface is placed in a chiral nihility medium, only a backward wave can be seen as a reflected wave, whereas in chiral media two reflected forward waves can exist [7,22-25]. is the modal effective refractive index.
For guided modes to occur within the core and evanescent tails within the cladding we require: 0 and 0 2 2 2 2        c f k k . For surface modes to evolve along an interface between two media, opposite permittivity and permeability
(such as DNM and chiral material as in our study) must be realized [26] along that interface. Since these waves decay exponentially far away from the interface in
both …show more content…
i.e. even
LCP curves are now the former. In Figures (8.a and 9.a), it is clear that odd RCP and even LCP guided modes are bent and have two gradients or group velocities near cut off; one is negative (backward waves) and the other is positive (forward waves), i.e. possessing double-degeneracy. We also notice that as the chirality increases (Figures:8b and 9.b), the dispersion curves increase monotonically and the waveguide can no longer support backward waves. Moreover, the curves are shifted towards higher values of kod. It is interesting to notice that the dispersion curve of LCPo increases very dramatically with decreasing the film width. This is very promising in optical sensor applications [23]. The LCPo guided mode cannot coexist with any other higher-order modes. This novel property suggests an important bandpass regime to filter the effect of DNM waveguides without apparent the usage of resonant structures [11].
Figure 10 shows the power flow distributions at kod=4 and N =1.7 for odd and even modes. It is obvious that when the material becomes a chiral nihility,