The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In communication systems with interference, the performance of traditional adaptive beamforming to search the direction of angle (DOA) of incoming desired signal degrades because of mismatch between the true array response and the assumed array response of desired signal in a receiver antenna array. In this paper, we approach the method of maximum output Signal-to-Interference-plus-Noise Ratio (SINR)...
Beamforming is a famed signal processing technique which boosts the signal power received from the desired direction. The threedimensional (3D) beamforming technique has obtained a growing attention due to its potential that enables several strategies like user specific elevation beamforming and vertical sectorization compared to conventional horizontal beamforming. In this paper, a new 3D multi-band...
Next generation solar energy converters rely on a combination of principles involving optics, thermodynamics, and device physics. To aid in the experimental design, it is often necessary to develop theoretical and computational models to guide the research. For traditional solar cells, standard computational packages are available; however, for more advanced designs incorporating sub-wavelength optical...
We investigate both optical and electrical properties of organic photovoltaics (OPVs) by a comprehensive multiphysics model.Using a unified finite-difference approach, the multiphysics model for OPVs is established for seamlessly connecting photon absorption to the exciton delocalization and diffusion, and to carrier transport and collection. Here we solve the Maxwell's equations and semiconductor...
With the rapid development of photovoltaic (PV) technology, ultrathin crystalline silicon (c-Si) solar cells (SCs) with the thickness of only 10 ‼ 20 µm have attracted tremendous attention due to the reduced material loss and a high photoelectric conversion efficiency (PCE). However, the shortened active layer decreases the optical-path of incident light substantially and thus lowers optical absorption...
In this work, two electro-optic (EO) modulation schemes based on the Pockels effect — the quasi-linear and nonlinear EO modulation are compared and analyzed. Then, we find that the modulation efficiencies with these two schemes are at the same level relation of Vπ and L, but the quasi-linear scheme has to face the critic limitation in the realistic EO modulation implementation process. Thereby, with...
Thin film materials have been attracted many new and promising applications in numerous technology fields from microelectronics to biosensors. Laser processing of those films is still explored to achieve targeted properties as optical and electrical, thermal or mechanical high properties. Fast optical methods were developed during the last decade for the monitoring of the real-time or the time-resolved...
Fabrication of metasurfaces by subtractive and additive (ablation and polymerisation) techniques are demonstrated using ultra-short laser pulses. Stokes polarimetry was used to determine optical retardance from laser structured regions on the surface and in the bulk.
Laser-materials interactions at high intensity have important implications for many scientific and industrial applications. In order to gain knowledge on the physical processes that occur in such processes, i.e., material excitation and response to the laser irradiation at different time scales, experimental tools that allow to observe and analyze in-situ and in real time these interactions are very...
Low-profile, high-gain circularly polarized antennas are highly desired in modern space and communication systems because they not only reduce the size, weight, and cost of the communication system but also reduce polarization mismatch resulting from the multipath interference of wave propagation. Because of their low cost, simple structure, and good integration capability, microstrip patch antennas...
Ultrashort laser interactions with dielectrics are numerically investigated by using a multi-physics approach based on Maxwell's equations coupled with a multiple rate free carrier density equation and with the integrated two-temperature model describing the energy transfer from the conduction band electrons to lattice. The model accounts for a complete Keldysh photoionization rate, impact ionization...
We have developed a strategy to image the nonlinear propagation of high-intensity femtosecond pulses while they propagate in fused silica. We have studied the propagation of Bessel beams in the regime where they allow for drilling high-aspect ratio nanochannels in single shot. Experimental results provide useful insights for the modelling.
Plasmons in highly doped graphene are highly tuneable by external means (electrically, thermally, magnetically, nonlinearly) and exhibit record levels of confinement. Consequently, the interaction with optical quantum emitters is extraordinarily intense, rendering these excitations an excellent platform for the implementation of quantum optics phenomena at the nanometer scale. In particular, we predict...
Terahertz Photonics is an emerging field with a great amount of potential science and applications. Functional optical technologies to control the amplitude, phase and polarization of Terahertz waves are crucial for advancing the THz technology. In this work, we study the coherent perfect absorption (CPA) [1] of a chiral structure and show its potential use as polarization control for THz waves.
We report our recent progress in characterizing sub-bandgap surface-state absorption (SSA) and defect-state absorption (DSA) in foundry-fabricated silicon waveguides and microring resonators in 1310–1550nm wavelengths. While SSA is widely regarded as a fundamental linear absorption loss due to surfaces and interfaces for silicon waveguides and microring resonators, our previous work has shown that...
We measure the opto-electronic properties of femtosecond-laser-ablated GaAs and demonstrate its utility towards THz devices. In particular, we show that laser-ablated THz antennas are 65% more efficient than non-ablated antennas at high powers. Our results demonstrate the possibility of using femtosecond-laser-ablation as a cost-effective technique to engineer material properties for THz devices.
Silicon has many favorable attributes from both the device physics and manufacturing standpoints, and is therefore the pre-eminent material for micro- and nanoelectronics. Furthermore, due to its transparency at infrared wavelengths, silicon-based integrated photonics play a key role in modern optical communications devices. Silicon-based nano-optical antennas have also attracted much interest recently,...
The plasmonic metamaterial perfect absorber (MPA) is a recently developed branch of metamaterial which exhibits nearly unity absorption within certain frequency range [1–6]. The optically thin MPA possesses characteristic features of angular-independence, high Q-factor and strong field localization that have inspired a wide range of applications including electromagnetic wave absorption [3, 7, 8],...
During the last years, a Generalized Signals and Systems Theory (GSST) is been developed by our research group. The latest version of the GSST includes important concepts concerning the generalization of the (i) study of physical systems by means of infinite dimensional signal and linear-invariant and non invariant-operator spaces; (ii) concepts associated to sets of impulse responses rigorously explained...
The Feature Selective Validation (FSV) Method has been developed as a standard technique to mimic an expert's opinion of concurrence between CEM and measurement datasets. This paper presents a comparison of SBR predictions and measurements obtained from a scattering problem of a ship. Based on the RCS curves these datasets should appear trendly and quantitive similar. The objective is to present a...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.