ABSTRACT
In this paper, we analyze and simulate the lossless propagation of lightwaves in the active metal-semiconductor-metal plasmonic waveguides (MSMPWs) at the wavelength range of 1540-1560 nm using a quantum dot (QD) active medium. The Maxwell's equations are solved in the waveguide, and the required gains for achieving lossless propagation are derived. On the other hand, the rate equations in quantum dot active regions are solved by using the Runge-Kutta method, and the achievable optical gain is derived. The analyses results show that the required optical gain for lossless propagation in MSMPWs is achievable using the QD active medium. Also, by adjusting the active medium parameters, the MSMPWs loss can be eliminated in a specific bandwidth, and the propagation length increases obviously.
ABSTRACT
In this paper, a two-dimensional nonlinear plasmonic directional coupler (2D-NPDC), with 90° waveguide bends, has been numerically analyzed by the finite-difference time-domain (FDTD) method, considering the nonlinear response of metal due to the ponderomotive force. It has been shown that the required switching power of the 2D-NPDC is 0.05% of that when only the dielectric is nonlinear and the nonlinearity of metal is neglected. Also, the cross-phase modulation (XPM) nonlinear effect has been investigated, which the power for switching is decreased significantly compared to the one with the self-phase modulation (SPM) effect.
ABSTRACT
In this paper, we have proposed a magneto-optic (MO) surface plasmon polariton (SPP) modulator based on variations of refractive index. For description of modulator operation, we have analyzed the MO effects in the insulator-metal-insulator (IMI) SPP slab waveguides in a transversal configuration in which the applied magnetic field is parallel to the interfaces and normal to the wave propagation direction. We have derived an exact dispersion relation by considering MO effects for one of the side layers by the separation of variables method. The cut-off conditions have been studied for the SPP modes guided by IMI structures as a function of the variations of the dielectric constants of the side layers. We have shown that the SPP modes always propagate in a symmetric structure and the SPP odd modes do not have a cut-off dielectric constant in an asymmetric structure. Also, we have shown that in an asymmetric IMI configuration, the SPP even mode has a cut-off effective dielectric constant for all metal layer thicknesses. These configurations can be used to design active devices, such as switches and modulators to be used in photonic integrated circuits.
ABSTRACT
This paper presents a sheet of graphene as a simple band-pass filter in terahertz and infrared frequencies. The central frequency and quality factor of this band-pass filter can be tuned by changing the physical parameters, such as the substrate thickness, gate voltage, temperature, and conductivity of the graphene. The effects of these parameters on surface plasmon polariton waves and filter specifications are numerically depicted.
ABSTRACT
Using dispersive finite-difference time-domain (D-FDTD) simulations, we show that a pair of gold nanodisks stacked in a 'sandwich'-like (end-fire) configuration produces a large enhancement of the magnetic field when irradiated with a plane optical wave, if the distance between the nanodisks is optically small. The effect, which can be rationalized in terms of a magnetic dipole resonance, is due the excitation of a hybridized asymmetric plasmon mode, in which the induced electrical dipoles in the two disks oscillate out-of-phase. The strong magnetic response, together with the simple morphology, suggests that Au nanosandwiches are suitable elementary building blocks for optical metamaterials that exhibit negative refraction.
