Analysis of InGaAsP-InP Double Microring Resonator using Signal Flow Graph Method

The buried hetero-structure (BH) InGaAsP-InP waveguide is used for asystem of double microring resonators (DMR). The light transmission and location ofresonant peaks are determined for six different sets of ring radii with different ordermode numbers. The effect of changing middle coupling coefficient on the box likeresponse is studied. It is found that the surge of coupling coefficient to the lower valuesmakes the through port resonance peaks sharper and for a larger amount of middlecoupling values, the transmission decreases according to the order mode numbers. TheDMR design with a small middle coupling and close values for rings perimeters cangenerate practical pass bandwidth of the resonant transmission peak. Moreover, anymodification in resonant mode numbers and middle coupling coefficient can change thewidth and height of the box like response. A DMR simulated results with the freespectral range (FSR) of 10.2 nm is validated by comparing with the experimental data.Achieved results are practical in the filtering process of optical communication.