A New Theory of Wood’s Anomalies on Optical Gratings

Optical properties of photonic crystal slabs with an asymmetrical unit cell

“…Such resonances, being Fano-type discrete states in the continuum background, are characterized by a finite frequency linewidth due to radiative losses even in transparent materials. The existence of radiative losses seems to exclude a possibility of full reflectivity, however, all the models [11,14,22,23,24,25] show this effect in transparent PCS. Moreover, it appears that very different physical models, with only one common thing, the existence of any resonance, predict a qualitatively similar behavior of the PCS optical response, see, e.g., discussions in [14,18,26,27].…”

“…Measuring reflection from asymmetric structure appears to be not a promising method for the PCS optical characterization, and a question arises, which optical properties are more sensitive to the PCS structure? Meanwhile, notwithstanding a long history of the investigations (see, e.g., in [11,21]), starting actually from the optical gratings, which can be understood as one-dimensional (1D) PCS, their properties look sometime amazing and even contradictory.One example is the nontrivial symmetry properties of reflection and transmission from asymmetric PCS. Namely, it was demonstrated [17] experimentally and numerically that the reflectivity from 180 o -rotationally non-invariant (in the PCS plane) metal gratings on a dielectric substrate is always symmetric, whereas the transmission is not.…”

“…4, 5). The authors [17] find this astonishing, because the calculated fields distributions inside the PCS appear to be very different for the illumination from different sides.Another example is the so called anomalous full reflection in zeroth diffraction order in transparent PCS, when reflectivity peaks to unity resonantly [11]. It is established that excitation of surface or quasiguided modes in PCS is responsible for this resonant behavior.…”

“…Another example is the so called anomalous full reflection in zeroth diffraction order in transparent PCS, when reflectivity peaks to unity resonantly [11]. It is established that excitation of surface or quasiguided modes in PCS is responsible for this resonant behavior.…”

Filter Response of Resonant Waveguide Dielectric Gratings at Plane-Wave Conical Incidence

“…Multilayered dielectric structures composed by homogeneous layers [7] or containing a periodic variation along any of the dielectric layers [8][9][10][11][12], have been subject of great interest for many years. In such structures, leaky modes can be excited in suitable geometries, producing total reflection at the resonance wavelengths.…”