We have proposed and realized nonreciprocal light propagation by a structure consisting of graphene photonic crystal and magneto-optical semiconductor. The nonreciprocal transmission is caused by magnetic Tamm plasmon polaritons which exit on the interface of graphene photonic crystal and magneto-optical material. Transmission spectrum is investigated to analyze the influence of structural parameters, external magnetic field, and graphene chemical potential on magnetic Tamm plasmon polaritons. We show that it is possible to realize active control on unidirectional light by altering external magnetic field and graphene chemical potential. And one-way transmission can be easily switched from forward to backward propagation.
Fano resonance is investigated by finite element method in plasmonic waveguide system which comprise a stub and a side coupled split ring resonator. We show that Fano resonance wavelength has a linear relation with refractive index of the material. Based on the sensitivity to the circumstance, a high performance refractive index sensor is proposed. This sensor can take advantage of easy on-chip integration of SPPs and high sensitivity of Fano resonance. This work may provide guidance for the design of on-chip nanosensors and other applications in integrated optical circuit.
Controlling the propagation of light by using a square lattice photonic crystal (PC) is investigated. Beam bending is
accomplished by gradually varying the orientation of dielectric rods. The beam redirection relies on gradual modification
of PC structural parameters which make the group velocity location dependent. A Y-shaped beam splitter is then
designed by means of a composite structure consisting of two graded PCs. The splitting ability of the beam splitter is
further discussed. We demonstrate that one input beam can be split into two output beams. The equal and unequal energy
splitting are obtained.
We propose a method to bend a self-collimated beam propagating in a photonic crystal (PhC). The PhC is made of
elliptically dielectric rods. We investigate the effect of orientation angle of elliptical rods on the light propagation. The
propagation of light is analyzed by the use of finite-difference time-domain technique. A modulated PhC is then
designed by gradually varying the orientation of ellipse. We demonstrate that the gradually variation of orientation angle
results in smooth change in the propagation direction. The capability of bending light by gradually modulated PhC
structure suggests a new direction for the realization of PhC light circuits.
The effects of imperfection in fabrication process on the focusing property of photonic quasicrystal (PQC) slab are
investigated. Two kinds of imperfections, in which the radii and the positions of all cylinders in quasicrystal slab
independently varied at random, are considered. The results show that the randomness adversely affects on the focusing
performance of the quasicrystal lens. And the TE mode is more influenced by disorders than the TM mode. The tolerance
of focusing function to radius disorder is smaller than to positional disorder. Our results will contribute to the design of
PQC-based focusing devices.
The controllable focusing property of a flat lens is investigated by changing the external voltage. The
tunability is introduced based on electro-optical effect. The flat lens is a slab of photonic crystal
composed of air cylinders in electro-optic material background. The results demonstrate that focusing
can be achieved by the flat photonic crystal slab. Moreover, the focal length of the flat lens can be
tuned continuously by the applied voltage, which might have potential applications in photoelectric
The nonlinear refractive index model is used to analyze the diffraction properties of reflection volume hologram. Using characteristic matrix method of multi-layer system, we analyzed the wavelength selectivity and angular selectivity of the diffraction efficiency of reflection volume hologram for P and S polarization. Compared to the classic pure sinusoidal index modulation, this nonlinear model gave more practical results.