Ehsan shah Hosseini

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Electromagnetic phased arrays at radio frequencies are well known and have enabled applications ranging from communications to radar, broadcasting and astronomy. The ability to generate arbitrary radiation patterns with large-scale phased arrays has long been pursued. Although it is extremely expensive and cumbersome to deploy large-scale radiofrequency(More)
The aim of this study was designed to evaluate the possible protective effects of Nigella sativa (NS) on the neuronal injury in the sciatic nerve of rats. The rats were randomly allotted into one of the three experimental groups: A (control), B (only trauma) and C (trauma and treated with NS); each group contain 10 animals. Sciatic nerve injury was(More)
Silicon photonics has emerged as the leading candidate for implementing ultralow power wavelength-division-multiplexed communication networks in high-performance computers, yet current components (lasers, modulators, filters and detectors) consume too much power for the high-speed femtojoule-class links that ultimately will be required. Here we demonstrate(More)
—We design and demonstrate a new microring modu-lator geometry utilizing low-resistance interior ridge contacts and a hard outer waveguide wall to achieve high-speed operation in a device with a large free spectral range (FSR). The depletion-mode silicon microring modulator utilizes a hybrid vertical–horizontal junction to maximize the frequency response(More)
On-chip, high-power, erbium-doped distributed feedback lasers are demonstrated in a CMOS-compatible fabrication flow. The laser cavities consist of silicon nitride waveguide and grating features, defined by wafer-scale immersion lithography and an erbium-doped aluminum oxide layer deposited as the final step in the fabrication process. The large mode size(More)
Record low optical threshold power and high slope efficiency are reported for arrays of distributed Bragg reflector lasers integrated within an ultra-low-loss Si 3 N 4 planar waveguide platform. Additionally, arrays of distributed feedback laser designs are presented that show improvements in pump-to-signal conversion efficiency of over two orders of(More)
In this Letter, we report on the first integrated four-port polarizing beam splitter. The device operates on the principle of mode evolution and was implemented in a silicon-on-insulator silicon photonics platform and fabricated on a 300 mm CMOS line using 193 nm optical immersion lithography. The adiabatic transition forming of the structure enabled over a(More)
In this Letter, we demonstrate an 8×8 apodized silicon photonic phased array where the emission from each of 64 nanoantennas was tailored to exhibit Gaussian-shaped intensity distributions in the near field so that the sidelobes of the generated far-field optical beam were suppressed compared to that of a uniform phased array. With the aid of the 72(More)
We demonstrate monolithic 160-µm-diameter rare-earth-doped microring lasers using silicon-compatible methods. Pump light injection and laser output coupling are achieved via an integrated silicon nitride waveguide. We measure internal quality factors of up to 3.8 × 10 5 at 980 nm and 5.7 × 10 5 at 1550 nm in undoped microrings. In erbium-and ytterbium-doped(More)