Showing 3 results for Ghasemi
A. Asgari, S. Razi, F. Ghasemi,
Volume 4, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 4, No. 2, Summer-Fall 2010)
Abstract
In this paper, we present calculations for different parameters of quantum dot infrared photodetectors. We considered a structure which includes quantum dots with large conduction-band-offset materials (GaN/AlGaN). Single band effective mass approximation has been applied in order to calculate the electronic structure. Throughout the modeling, we tried to consider the limiting factors which decline high temperature performance of these devices. Temperature dependent behavior of the responsivity and dark current were presented and discussed for different applied electric fields. Specific detectivity used as figure of merit, and its peak was calculated in different temperatures. This paper indicates the state of the art in the use of the novel III-N materials in infrared detectors, with their special properties such as spontaneous and piezoelectric polarizations. It was found that, III- nitride Quantum dots have a good potential to depress the thermal effects in the dark current which yields the specific detectivity up to~ 2107 CmHz 1/ 2/W at room temperature.
Dr. Esmaeil Shahriari, Dr. Mohammad Moradi, Dr. Mohsen Ghasemi Varnamkhasti,
Volume 9, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 9, No 2, Summer-Fall 2015)
Abstract
In this research, Ag nanoparticles were prepared by using g-radiation at concentration of 5.18×10-3 M and irradiated at different doses. A green laser was employed as excited source for measuring nonlinear refractive index and absorption coefficient. The measurements were done by z-scan method for both, closed and open aperture at temperature room. We deduced that with growth of size of Ag nanoparticles, nonlinear refractive index increased while absorption coefficient of samples decreased
Ms. Fatemeh Ghasemi, Dr. Parviz Parvin, Ms. Najme Alsadat Hosseini Motlagh, Ms. Fatemeh Mirzaee, Mr. Mohammad Keraji, Mr. Ali Bavali,
Volume 9, Issue 2 (International Journal of Optics and Photonics (IJOP) Vol 9, No 2, Summer-Fall 2015)
Abstract
Simultaneous laser induced- breakdown spectroscopy (LIBS) and acoustic response techniques as well as Laser induced fluorescence (LIF) are applied to investigate the abnormal lymph tissues due to Hodgkin disease. The spectral shift in the emissive fluorescence of the cancerous tissues has been observed respect to the normal ones. Regarding LIBS, the concentrations of Ca and Na trace elements have been identified to be higher in the cancerous samples. In addition, the acoustic response of cancerous tissues has been elevated against healthy ones. The distinct differences in the spectra are taken into account for early and the rapid identification and diagnosis.
