Optical bistability in mobius microring resonator

Abstract

Optical bistability is one of the nonlinear properties that produce an essential light control which contributes in various photonics applications such as all-optical switching and optical memory. In this thesis, bistability behavior of optical signals generated in microring resonator (MRR) systems using bright soliton input pulses with 1.55 µm wavelength is studied. The generation of the bistable signals is mathematically analyzed through the transfer matrix analysis and simulated by the MATLAB software version 2014a. The behavior of the propagated input pulses in terms of intensity and phase shift is investigated for different configurations including All-pass MRR, Add-drop MRR and PANDA MRR systems. Three novel Mobius MRR configurations consist of All-pass Mobius MRR, Add-drop Mobius MRR and PANDA Mobius MRR configurations are proposed and the light treatment through Mobius MRR systems is analytically studied and compared with conventional MRR systems. For determining the effect of physical parameters such as ring radius, control power variation and coupling coefficients on the output pulse, the optical hysteresis loops of bistable signals are generated via silicon-on-insulator nonlinear MRR configurations. The analyses of the results are conducted by calculating the output switching power, input threshold power and hysteresis width of bistable loop for radius variation from 1 µm to 6 µm with an increment of 1 µm, change of coupling coefficient from 0.4 to 0.9 with increment of 0.1 and variation of controlled power from 50 mW to 100 mW with increment of 10 mW. It is found that small coupling coefficients enhance the hysteresis width and output switching power of optical bistable loops. The value of output switching power obtained at the output port of Add-drop Mobius MRR is 30.26 mW which is higher than those obtained from All-pass Mobius and PANDA Mobius MRR configurations. The threshold powers of the All-pass Mobius, Add-drop Mobius and PANDA Mobius configurations for on switching operations are obtained as 20.59 mW, 31.39 mW and 25.19 mW respectively. It is found that, optimization of the Mobius MRR system can be conducted by increasing the external radius of Mobius ring waveguide and decreasing the coupling coefficient with implementation of the high control power. In this work, the Mobius configurations are introduced as a convenient compact design to generate optical bistability in comparison with conventional configurations of nonlinear MRR system.