Mahboubeh Dolatyari

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Solution-processed ultraviolet photodetectors based on passivated and unpassivated zinc oxide (ZnO) nanorods, in which the ZnO nanoparticles are synthesized by a hydrothermal method, are demonstrated and characterized. Photoconductive photodetectors fabricated using simple solution processing have recently been shown to exhibit high gains and outstanding(More)
Proximity interaction of a travelling electron beam near the surface of a structured metallic slab excites effective surface Plasmon at lower frequencies. Due to the existence of a velocity phase match, the Terahertz (THz) frequencies-known as Smith-Purcell radiation (SPR)-are produced. Here, we investigate two-color SPR characteristics of a ladder-type(More)
At lower frequency regime, altering the surface structure modifies the characteristics of propagating effective surface plasmons (ESPs), particularly their interaction with light. Movement of an electron beam in the proximity of the surface of a structured metallic grating excite these ESPs, which due to existence of a velocity phase match, they are able to(More)
Weak light absorption of graphene has limited the responsivity of graphene-based photodetectors. On the other hand, the slow response of PbSe as a mid-infrared range (MIR) detector makes this type of detector unsuitable as a commercial detector. Here, we report a fast MIR detector based on hybrid graphene-PbSe nanorods. For this purpose, a few-layer(More)
In this paper, we present a three dimensional numerical study on a terahertz frequency multiplier. The process of frequency multiplication is proposed via study of spontaneous Smith-Purcell (SP) radiation. Through introducing a single electron bunch perturbation which is passing over above a metallic grating, and due to interaction of electron bunch with(More)
In this paper, conventional transformation optics is applied to design an optical cloak in mid-IR region (5 μm) for TM polarization to conceal cylindrical object using composite optical structures. Effective medium theory in this method will be used. Based on required permittivity and permeability for TM radiation, we approximate the cloak region by(More)
Simulation results based on a comprehensive model show that the amount of mode splitting in typical long period fiber grating (LPFG)-based bending sensor rises linearly in small range of bending. According to simulation results, this range of sensing in a typical LPFG-based bending sensor reaches to almost 5m<sup>-1</sup>. On the other hand, fiber Bragg(More)
In this paper, a broadband carpet cloak using nanocomposite layers to operate in whole 3&#x2013;5-&#x03BC;m wavelength band is designed successfully. For this purpose, spherical nanometals or doped semiconductors with desired plasma frequency are proposed. In this way, the refractive index of the cloak as an analytic function is considered by optical(More)
In this paper, a composite medium based metamaterial with random distribution of nanoparticles in vacuum host to achieve negative effective refractive index in the visible wavelength range is suggested for invisibility purposes. Our calculations show that structures including single metal (dielectric) spheres and core-shell structures with metallic core and(More)
In this paper, for the first time, graphene nanoparticles modified by organic molecules (thiophene-2-carbaldehyde, thiophene-2-carboxylic acid, or pyridine-4-carboxylic) are used for the fabrication of infrared (IR) detectors. To compare the results, the properties of the photodetector fabricated based on the synthesized unmodified graphene were also(More)