The authors demonstrate the triggering of surface plasmons at the interface of a metal grating and a photovoltaic bulk heterojunction blend of alternating polyfluorenes and a fullerene derivative. An increased absorption originating from surface plasmon resonances is confirmed by experimental reflection studies and theoretical modeling. Plasmonic resonances are further confirmed to influence the extracted photocurrent from devices. More current is generated at the wavelength position of the plasmon resonance peak. High conductivity polymer electrodes are used to build inverted sandwich structures with top anode and bottom metal grating, facilitating for triggering and characterization of the surface plasmon effects.

We report a new computational method based on the recursive Green's function technique for calculation of light propagation in photonic crystal structures. The advantage of this method in comparison to the conventional finite-difference time domain (FDTD) technique is that it computes Green's function of the photonic structure recursively by adding slice by slice on the basis of Dyson's equation. This eliminates the need for storage of the wave function in the whole structure, which obviously strongly relaxes the memory requirements and enhances the computational speed. The second advantage of this method is that it can easily account for the infinite extension of the structure both into air and into the space occupied by the photonic crystal by making use of the so-called "surface Green's functions". This eliminates the spurious solutions (often present in the conventional FDTD methods) related to e.g. waves reflected from the boundaries defining the computational domain. The developed method has been applied to study scattering and propagation of the electromagnetic waves in the photonic band-gap structures including cavities and waveguides. A particular attention has been paid to surface modes residing on a termination of a semi-infinite photonic crystal. We demonstrate that coupling of the surface states with incoming radiation may result in enhanced intensity of an electromagnetic field on the surface and very high Q factor of the surface state. This effect can be employed as an operational principle for surface-mode lasers and sensors.

We propose and analyze novel surface-state-based waveguides in bandgap photonic crystals. We discuss surface mode band structure, field localization and effect of imperfections on the waveguiding properties of the surface modes. We demonstrate that surface-state-based waveguides can be used to achieve directional emission out of the waveguide. We also discuss the application of the surfacestate-waveguides as efficient light couplers for conventional photonic crystal waveguides. Surface states reside at the interface between a photonic crystal and open space, decaying into both mediae [1] and propagating along the boundary. In a square lattice photonic crystal the surface states appear in the bandgap when a boundary of a PC is modified in some way, by, e.g., truncating the surface rods, shrinking or increasing their size, or creating more complex surface geometry [1,8,9,10,11]. The surface modes in a semiinfinite photonic crystal represent truly Bloch states with the infinite lifetime and Q factor, and consequently do not couple to incoming/outgoing radiation. At the same time, it has been demonstrated that when the translational symmetry along the boundary of the semi-infinite crystal is broken, the surface mode turns into a resonant state with a finite lifetime, which can be utilized for lasing and sensing applications [11,12]. It has also been recently shown that with the help of surface modes it is possible to achieve directional beaming from the waveguide opening on the modified surface of a photonic crystal [13,14]. Surface states there, coupled with outgoing waveguide radiation, suppress diffraction and focus outgoing beam. At the same time, so far there have been no reports on study of guiding properties of PC surfaces.In order to study surface states in photonic crystals,

We perform numerical studies of the effect of sidewall imperfections on the resonant state broadening of the optical microdisk cavities for lasing applications. We demonstrate that even small edge roughness ( λ/30) causes a drastic degradation of high-Q whispering gallery (WG) mode resonances reducing their Q-values by many orders of magnitude. At the same time, low-Q WG resonances are rather insensitive to the surface roughness. The results of numerical simulation obtained using the scattering matrix technique, are analyzed and explained in terms of wave reflection at a curved dielectric interface combined with the examination of Poincaré surface of sections in the classical ray picture.

We study propagation of TM-and TE-polarized light in two-dimensional arrays of silver nanorods of various diameters in a gelatin background. We calculate the transmittance, reflectance and absorption of arranged and disordered nanorod arrays and compare the exact numerical results with the predictions of the Maxwell-Garnett effective-medium theory. We show that interactions between nanorods, multipole contributions and formations of photonic gaps affect strongly the transmittance spectra that cannot be accounted for in terms of the conventional effective-medium theory. We also demonstrate and explain the degradation of the transmittance in arrays with randomly located rods as well as weak influence of their fluctuating diameter. For TM modes we outline the importance of skin-effect, which causes the full reflection of the incoming light. We then illustrate the possibility of using periodic arrays of nanorods as high-quality polarizers.