Based On The Characteristics Of The Micro-ring Resonator Signal Flow Graph Theory Analysis

With more and more increasing demands for information, enhancing the capacity and speed of the optical fiber communication has become a problem to be urgently solved. Large-scale integrated optics is an important part of all-optical networks, its development undoubtedly has great significance in solving this problem. The micro-ring resonator with multiplex function, structural simplicity and high integration has become a research focus in the fields of integrated optics.The typical researching approach to micro-ring resonator is the coupled mode theory which is based on Maxwell equations. The method either in space or in time can be expressed by equations. However, studying multi-ring system with the approach more complicated, so it is not fit for practical application. In this paper, a simple, intuitive graphic method called signal flow graph method to analyze the output characteristics of micro-ring resonator.The main work of this paper is founded on the model of general parameters based on transfer matrix. Firstly, using the all-pass single micro-ring resonator as an example, the approach of the signal flow graph method (SFG) in optical signal system are introduced, and the condition of resonance of the system is analyzed. Secondly, the system transfer function of the add/drop single micro-ring resonator filter with parallel channel, add/drop"Series-coupled"and"Parallel-coupled"double micro-ring resonator filter with parallel channel are derived using the signal flow graph method. For the"Series-coupled"structure, the performance is mainly determined by the coupling coefficients between ring and ring. The critical coupling coefficient is obtained by simulation when achieving the maximal flat output wave crest. For the"Parallel-coupled"structure, the good ship of spectral response is achieved by optimizing the ring distance. Finally, the transfer function of single micro-ring resonators wavelength multiplexers with vertical channel is derived. The influence of coupling coefficient on the drop port output spectrum width, the insertion loss, and the crosstalk between channels is analyzed and discussed.