Phase modulated circles in a sunflower-type circular photonic crystal with ultra-small mode area and high-Q cavity

A modified sunflower type circular photonic crystal defect cavity consisting of 10 concentric circles is studied where the defect cavity is created by removing the central hole. The resonant characteristics of the CPC defect cavity with gradually shifted phase angle in successive hole circles are analyzed. The resonant transverse electric (TE) and transverse magnetic (TM) mode frequencies were calculated by 2D finite difference time domain (FDTD) method. The field profiles at resonant frequencies are calculated and mode areas (A_m) are determined from both TE and TM mode profiles. It is found that temporal decay of field energy in the cavity is exponential. From the decay of the energy in the cavity, the quality factor (Q) of the PC cavity is determined. Finally the impact of phase modulation on Q and A_m of the designed CPC defect cavity is examined.