Refraction-based photonic crystal diode

Abstract

A system composed of air holes in a dielectric host to form two square photonic crystals, with the same orientation and lattice constant but different scatterer radii, making an interface along their body diagonals, is numerically demonstrated to facilitate unidirectional light transmission. Band structure computations are carried out via the plane wave expansion method, whereas finite-difference time-domain simulations are carried out to investigate the transient behavior. Unidirectional light transmission is achieved over two adjacent stop bands along the ΓX direction, which are circumvented in the forward direction by scaling down the wave vector and rotating the surface normal. Contrast ratios as high as 0.9 are attained within the lower stop band.

Wideband unidirectional transmission with tunable sign-switchable refraction and deflection in nonsymmetric structures

“…Because of reciprocity, additional transmission channels should be opened for one of the two opposite illumination directions, which can be connected with higher diffraction orders [1][2][3][4][5][6][7][8] or polarization conversion [9][10][11] and can exploit benefits of inclining interfaces. [12][13][14] In the first case, asymmetry in transmission is inspired, in fact, by asymmetric diffractions at the opposite interfaces of a grating-like structure. The most interesting regime of asymmetric transmission is probably that with vanishing transmission for one of the two opposite incidence directions, so that unidirectionality takes place.…”

Visible-frequency asymmetric transmission devices incorporating a hyperbolic metamaterial

“…A symmetric transmission using reciprocal electromagnetic devices has recently become a thriving research topic owing to potential applications in integrated photonic systems for communications and information processing [1][2][3][4][5][6][7][8][9][10][11][12] , such as, directionally-sensitive beam splitting 2,3 , multiplexing 4 and optical interconnection 7,8 . This Lorentz-reciprocal effect is characterized by the high contrast between forward and reverse transmission under illumination from anti-parallel directions.…”

“…Though reciprocal asymmetric transmission devices cannot be used for functions attainable only with non-reciprocal-active devices, such as optical isolation [13][14][15][16] , they have unique advantages such as small footprint, broad asymmetric transmission bandwidth and passive operation. Asymmetric transmission can be achieved through the use of artificial structures, such as, nonsymmetric gratings [2][3][4][5][6]11,12 , photonic crystals 7,8 and split-ring resonators 1,9,10 which break spatial inversion symmetry. Nevertheless, fabrication and alignment challenges associated with the intrinsic complexity of such approaches have not so far enabled structures with an efficient asymmetric transmission response at visible frequencies.…”

Optical Diode Based on Two-Dimensional Photonic Crystal

“…However, unfortunately, lack schemes for air-holed 2D PhC optical diode can be found. One scheme is based on the PhC heterostructure with directional bandgap [28][29][30][31], and the other scheme is based on topology optimization [32]. The TE mode whose magnetic field is perpendicular to the slab is considered in all designs discussed in this section and most simulations are performed in 3D FDTD.…”