Saghaei's papers published in 2019

[1] H. Saghaei, P. Elyasi, and R. Karimzadeh, “Design, fabrication, and characterization of Mach–Zehnder interferometers,” Photonics and Nanostructures - Fundamentals and Applications, vol. 37, p. 100733, 2019, doi: 10.1016/j.photonics.2019.100733.

In this paper, the effects of physical parameters on the performance of unbalanced Mach–Zehnder interferometers (MZIs) are numerically studied by solving Maxwell's equations on a cross-section of the waveguide using the finite-difference eigenmode method. The MZIs are fabricated by the electron beam lithography with a single etch process on a silicon-on-insulator wafer. The transmission profiles and free spectral ranges (FSRs) of the fabricated MZIs are also measured using a custom-built automated measurement setup and compared with the simulation results of Corner analysis and Monte-Carlo analysis methods. Our comparison reveals that the measured FSRs of the fabricated MZIs are in the range determined by the Monte-Carlo analysis. While all measured FSRs are less than the FSRs indicated by the Corner analysis. Therefore, Monte-Carlo analysis can be used as an accurate numerical method for the study of photonic integrated circuits before fabrication.

[2] F. Tavakoli, F. B. Zarrabi, and H. Saghaei, “Modeling and analysis of high-sensitivity refractive index sensors based on plasmonic absorbers with Fano response in the near-infrared spectral region,” Applied Optics, vol. 58, no. 20, 2019, doi: 10.1364/AO.58.005404.

In this paper, we present various optical metamaterial nanoabsorbers with the aim of improving the refractive index sensitivity using the Fano response. The proposed absorbers consist of various parasitic elements such as single cross, broken cross, Jerusalem cross, and also single L and double L models. We numerically study their absorption and reflection using the three-dimensional finite-difference time-domain method and calculate the sensitivity and figure of merit (FOM) in every absorption peak (reflection dip). Our simulations reveal that the Fano resonance at longer wavelengths can be used for increasing the sensitivity and FOM. The proposed absorbers have been coated with an external material with a maximum thickness of 100 nm and refractive indices in the range of 1.05–1.2. We also study and compare the FOM for these structures. They are modified for 900 and 1200–1300 nm. The maximum FOM is achieved around 2400  RIU−1 for the double L nanoabsorber coated with 1.05 indexed material, while its sensitivity is 473 nm/RIU. This absorber is an appropriate component for the design of highly sensitive optical sensors.

[3] H. Saghaei and V. Van, “Broadband mid-infrared supercontinuum generation in dispersion-engineered silicon-on-insulator waveguide,” Journal of the Optical Society of America B, vol. 36, no. 2, p. A193, 2019, doi: 10.1364/josab.36.00a193.

In this paper, we numerically investigate near- and mid-infrared supercontinuum (SC) generation in dispersion-engineered silicon-on-insulator (SOI) waveguides employing a novel side-slotted core structure. The effect of waveguide parameters on the dispersion is studied to achieve optimum dispersion profiles for SC generation in the anomalous and normal dispersion regimes. Numerical results show that by applying an input pump pulse with 200 fs width and 400 W peak power at 2.1 μm wavelength in a 10-mm-long SOI waveguide, SC spectra as wide as 2.8 μm and 2.0 μm can be obtained in the anomalous and normal dispersion regimes, respectively. These waveguides are useful as compact on-chip silicon photonic sources for spectroscopic applications in mid-infrared wavelengths.

[4] A. Ghanbari, A. Kashani Nia, A. Sadr, and H. Saghaei, “A Comparative Study of Multipole and Empirical Relations Methods for Effective Index and Dispersion Calculations of Silica-Based Photonic Crystal Fibers,” Journal of Communication Engineering, vol. 8, no. 1, pp. 98–109, Jun. 2019, doi: 10.22070/jce.2019.4016.1125.

In this paper, we present a solid-core Silica-based photonic crystal fiber (PCF) composed of hexagonal lattice of air-holes and calculate the effective index and chromatic dispersion of PCF for different physical parameters using the empirical relations method (ERM). These results are compared with the data obtained from the conventional multipole method (MPM). Our simulation results reveal that the ERM is an accurate and fast method for dispersion analysis of PCFs with large pitch sizes. However, for small pitch sizes of PCFs, it is not as accurate as the MPM method. Therefore, ERM is a fast, simple and accurate method for modelling and analysis of Silica-based PCFs with large pitch sizes.

[5] M. Jahangiri, A. Alidadi Shamsabadi, and H. Saghaei, “Comprehensive Evaluation of Using Solar Water Heater on a Household Scale in Canada,” Journal of Renewable Energy and Environment, vol. 5, no. 1, pp. 35–42, Jan. 2018. doi: 10.30501/jree.2018.88491.

Canadian researchers are now trying to exploit much more energy from solar sources, hydropower, wind, and biomass. Given the fact that reducing the carbon pollutant level is a political priority in Canada, this paper studies the feasibility of providing sanitary hot water and space heating demands of a four-member family in 10 provinces in this country. The feasibility analysis was performed by T*SOL Pro 5.5 software, and radiation data were obtained by MeteoSyn software. Results indicated that the most suitable station in terms of using solar water heater was Regina, which supplied 35 % of the total heat load for space heating and sanitary hot water purposes. This accounted for 5074 kWh of heat for space heating (25 % of demand) and 3112 kWh energy for sanitary hot water (94 % of demand) using a 40 m2 solar collector. In addition, results are indicative of an annual amount of saving up to 2080 kg of CO2 in the Regina station and an annual reduction of 984 m3 in natural gas for this station. In conclusion, Canada has a potentially alluring market to utilize solar water heaters for providing sanitary hot water for the residential sector.