"All-Optical Switches Based on Atomic-Plasmonic Resonant Coupled System" is the title of the project completed by Maliheh Ranjbaran, a postdoctoral researcher of Shahid Beheshti University (SBU), under the supervision of Dr. Seyedeh Mehri Hamidi Sangdehi, a faculty member of the Laser and Plasma Research Institute of SBU and with the support of the National Science Foundation of Iran.
Maliheh Ranjbaran, who received her master's and PhD degrees in the fields of photonics and physics from SBU, said: “Ultra-fast all-optical switches have attracted the attention of many researchers in applications such as long-range communication networks. In an all-optical switch, the incoming light beam is absorbed or deflected by the presence or absence of another light beam during the light-light interaction process in a nonlinear material.”
She continued: “Various methods such as photonic crystal, thermo-optical and acousto-optical have been discovered so far. But optical switches that work with a small number of photons are more important in quantum information transmission networks. Alkali metal vapor is used in many of these switches. Considering that the nonlinear optical interaction in these materials is very small, in order to achieve such switches, it is necessary to use a method to strengthen this process. Among these methods are various methods of quantum interference, the use of high laser beam intensity, and amplifiers, which increase the power consumption of the system and, of course, the cost of construction. Therefore, there is a need for a method that eliminates the need for high power consumption by increasing the light-matter interaction.”
This researcher further stated: “What is proposed in this research is the combination of atomic and plasmonic resonance phenomena to reduce costs and increase productivity. This combination creates new capabilities in the engineering of spectral properties of materials.”
She clarified: “All-electric switches like transistors are the basis of digital circuit structure. Since in today's world, long-range communications are based on optical fibers, the processes of converting optical signals into electrical signals and vice versa are essential when receiving and sending information. Due to the need of this industry for very fast and numerous conversion processes, there is a need to use all-optical tools. All-optical devices have attracted much attention in quantum communication due to their lower cost, higher speed, and smaller dimensions.”
In the end, Ranjbaran pointed out: “Production of technical knowledge and laboratory samples of ultra-fast all-optical switches was one of our important goals in carrying out this project. However, because high-tech equipment was not available to us, we ran into problems in the middle of the research and our equipment was damaged. But because the results of this research in light-based quantum systems are extremely practical and vital, we did our best to achieve our goals.”