Marcelo N. Kawakatsu

Compact three-port optical two-dimensional photonic crystal-based circulator of W-format

A three-port optical circulator of W-format based on 2D photonic crystal is presented. This circulator is more compact as compared to the known one of the traditional Y-format. The W-circulator does not have rotational symmetry. As a consequence, the frequency responses for different port excitation are slightly different, as it is shown by symmetry analysis and by numerical simulations.

Compact optical switch based on 2D photonic crystal and magneto-optical cavity

A compact optical switch based on a 2D photonic crystal (PhC) and a magneto-optical cavity is suggested and analyzed. The cavity is coupled to two parallel and misaligned PC waveguides and operates with dipole mode. When the cavity is nonmagnetized, the dipole mode excited by a signal in the input waveguide has a node in the output waveguide. Therefore, the input signal is reflected from the cavity. This corresponds to the state off of the switch. Normal to the plane of the PhC magnetization by a dc magnetic field produces a rotation of the dipole pattern in the cavity providing equal amplitudes of the electromagnetic fields in the input and the output waveguides. This corresponds to the state on with high transmission of the input signal. Numerical calculations show that at the 1.55 μm wavelength the device has the insertion loss -0.42 dB in the on state, the isolation -19 dB in the off state and the switch off and on ratio P(on)/P(off) about 72. The frequency band at the level of -15 dB of the resonance curve in off state is about 160 GHz.

Nonreciprocal optical divider based on two-dimensional photonic crystal and magneto-optical cavity

We suggest and analyze a new nonreciprocal optical device based on two-dimensional photonic crystal and a magneto-optical cavity that simultaneously fulfills two functions: division of the input signal and isolation of the input port from two output ones. At the central frequency, the division of the signal between the output ports is -3 dB and the isolation of the input port from the output ones is about -25 dB. For the level -20 dB of this isolation, the calculated bandwidth is around 100 GHz at the wavelength 1.5 μm.

Enhancement of Faraday and Kerr rotations in three-layer heterostructure with extraordinary optical transmission effect

We theoretically investigate and optimize a multilayer planar structure with enhanced magneto-optical (MO) activity. The extraordinary optical transmission observed in a periodically perforated metal plate with subwavelength holes is used to produce a higher MO activity. We consider a three-layer structure that consists of a dielectric layer placed between the perforated metal and the MO layers. In this structure, we obtained the enhancement of Faraday rotation by three times and the Kerr effect by an order as compared to the published results.

A compact and simple loop-type planar antenna for broadband applications

We present in this work a loop-type planar antenna with compact, simple geometry and broadband features. The commercial softwares CST Microwave Studio and Zeland IE3D were used in the simulations and optimization of this antenna. The optimization was made for the input return loss bandwidth by varying the antenna geometric parameters. The antenna has 72 % bandwidth for a 10 dB input return loss, with a relatively flat gain within the operating bandwidth.

Enlarging the impedance matching bandwidth of wire and planar antennas using loop parasitic elements

We present in this work some theoretical and experimental results of utilization of loop parasitic elements in wire (dipole) and planar (patch and monopole) antennas for increasing the impedance matching bandwidth. The antennas were analyzed using our programs, based on the numerical resolution of the electric field integral equation (EFIE) by the method of moments (MoM), and using the commercial softwares IE3D and HFSS. In one of the case studied we compared numerical calculations with experimental data. The obtained results shown that the impedance matching bandwidth can be considerably enlarged with this method.

Planar elliptical UWB monopole antenna with high efficiency

We propose and simulate in this work a planar elliptical ultra-wideband monopole antenna with high efficiency. High efficiency of the antenna is archieved by applying some geometrical modifications in the conventional monopole antenna, followed by parametric optimization. The corners of the ground plane were rounded, the feeding line was designed with trapezoidal shape and the notch, also of trapezoidal geometry, was positioned under the feeding line. Two models of this antenna are presented. One has as attractive feature an excellent impedance matching with return loss level lower than −22 dB and the other one has very good radiation pattern characteristics in the entire UWB region. Both models have total effiency greater than 97% within almost entire UWB band, flat gain characteristic and and small transmission distortion.

Reconfigurable electromagnetic frequency selective surface with high Q-factor transmission resonance

We analyze a planar array composed from a normally magnetized ferrite substrate and metallization in the form of two concentric metal rings in a square cell. This structure possesses a high Q-factor transmission resonance and can be projected with two types of electromagnetic control. The first type is shifting of the resonance frequency of the trapped-mode and the second one is switching from a very high to a low level of transmission by a dc magnetic field. The characteristics of the array are investigated firstly by group theoretical methods and then some numerical results are presented using two different full-wave numerical methods.

Patch antenna with T-shaped probe feed for broadband applications

We suggest in this work a new type of patch antenna feeding, namely, T-shaped probe. In comparison to the known L-shaped probe, the T-shaped one permits to increase the coupling between the feeding line and the radiator. Two patch antennas configurations are presented which consist of a rectangular radiator proximity coupled to a T-shaped probe. In the first configuration, the input return loss bandwidth is increased significantly and also with a size reduction in comparison to the patch antenna with L-probe. In the second configuration, the antenna is combined with parasitic loops and this allows one to increase further the bandwidth and improve the impedance matching within the entire operating bandwidth.

Microwave switchable frequency selective surface with high quality factor resonance and low polarization sensitivity

We present a microwave switchable frequency selective surface with high quality factor transmission resonance. The high quality resonance is achieved by excitation of the trapped-mode in array with two concentric metal rings in a cell on a silicon substrate. Optical activation of the silicon substrate permits to switch off the transmission band.