Ahmedbond6331

We present a saline water-based absorber that can offer an extremely wide bandwidth of electromagnetic absorption in the microwave frequency regime. The designed absorber is a hybrid of saline water and Poly Tetra Fluoro Ethylene (PTFE) dielectric material, which exhibits an absorption level greater than 90% across the frequency band from 1.4 to 3.3 and 4.3 to 63 GHz, with a relative absorption bandwidth as high as 180%. Meanwhile, the sensitivity of the absorption against oblique incidence is studied for both TE and TM polarizations. Additionally, the absorption performance of this saline water-based absorber could be tunable by changing the salinity and the combination of different temperatures and salinity. To explain the mechanism, interference theory is employed to investigate the designed absorber, and the theoretically calculated results are well in agreement with the simulation. This design offers an effective and feasible way to construct tunable and ultra-broadband absorber in low-cost stealth technology.We theoretically investigate the optomechanically induced transparency (OMIT) phenomenon in a hybrid optomechanical system composing of an optomechanical cavity and a traditional one. A Kerr medium is inserted in the optomechanical cavity and the other traps the atomic ensemble. We demonstrate the appearance of electromagnetically and optomechanically induced transparency when there is only Kerr medium or atoms in the system. We give an explicit explanation for the mechanism of the transparency. Moreover, we set up new scheme for the measurement of Kerr coefficient and the single atom-photon coupling strength. It is shown that Kerr nonlinearity can inhibit the normal mode splitting (NMS) when the tunnel strength is strong coupling. Furthermore, in the output field, slow light and fast light are converted to realize the tunable switch from slow light to fast light. This study has some important guiding significance in the fields of the high precision measurement and quantum information processing.We present an image formation model for deterministic phase retrieval in propagation-based wavefront sensing, unifying analysis for classical wavefront sensors such as Shack-Hartmann (slopes tracking) and curvature sensors (based on Transport-of-Intensity Equation). We show how this model generalizes commonly seen formulas, including Transport-of-Intensity Equation, from small distances and beyond. Using this model, we analyze theoretically achievable lateral wavefront resolution in propagation-based deterministic wavefront sensing. Finally, via a prototype masked wavefront sensor, we show simultaneous bright field and phase imaging numerically recovered in real-time from a single-shot measurement.A theoretical approach based on the electromagnetic theory of optical fibers has been applied in the analysis of the evanescent modes of a chalcogenide fiber bend used as a probe in a fiber-based spectroscopic sensor, by the example of the detection of small amounts of an antigel additive in a diesel fuel. The absorbance of the loop probe calculated for each mode was compared with the results of spectrometer-based measurements. The role of the higher-order evanescent modes of a fiber bend has been revealed. The efficiency of using a loop probe has been shown to depend on conditions of light launching into the probe.We report on a method that allows microscopic image reconstruction from extreme-ultraviolet diffraction patterns without the need for object support constraints or other prior knowledge about the object structure. This is achieved by introducing additional diversity through rotation of an object in a rotationally asymmetric probe beam, produced by the spatial interference between two phase-coherent high-harmonic beams. selleck inhibitor With this rotational diffractive shearing interferometry method, we demonstrate robust image reconstruction of microscopic objects at wavelengths around 30 nm, using images recorded at only three to five different object rotations.The challenge of astronomical intensity interferometry is to detect the small photon-bunching signals of distant sources with a broad optical bandwidth. We have built a Hanbury Brown-Twiss-like laboratory intensity interferometer with a focus on a relatively broad bandwidth (1nm FWHM optical filter) and high photon rates (up to 10MHz) per channel compared to typical (non-astronomical) intensity interferometry applications. As a light source we use a green LED to simulate starlight. The LED has proven to be a compact high-power source of stochastic light with a special advantage of a small emission area, which favours spatial coherence. Using single-photon correlations, we detect a bunching signal in the second-order correlation function with a coherence time of less then 1ps and an amplitude of less then 4⋅10-4 and describe signal and background quantitatively for a 40 hours measurement. In this paper we show our setup, present the correlation measurements and compare them to theoretical expectations.Femtosecond laser hyperdoped silicon, also known as the black silicon (BS), has a large number of defects and damages, which results in unstable and undesirable optical and electronic properties in photonics platform and optoelectronic integrated circuits (OEICs). We propose a novel method that elevates the substrate temperature during the femtosecond laser irradiation and fabricates tellurium (Te) hyperdoped BS photodiodes with high responsivity and low dark current. At 700 K, uniform microstructures with single crystalline were formed in the hyperdoped layer. The velocity of cooling and resolidification is considered as an important role in the formation of a high-quality crystal after irradiation by the femtosecond laser. Because of the high crystallinity and the Te hyperdoping, a photodiode made from BS processed at 700 K has a maximum responsivity of 120.6 A/W at 1120 nm, which is far beyond the previously reported Te-doped silicon photodetectors. In particular, the responsivity of the BS photodiode at 1300 nm and 1550 nm is 43.9 mA/W and 56.8 mA/W with low noise, respectively, which is valuable for optical communication and interconnection. Our result proves that hyperdoping at a high substrate temperature has great potential for femtosecond-laser-induced semiconductor modification, especially for the fabrication of photodetectors in the silicon-based photonic integration circuits.