Ring resonators are useful elements especially in channel drop filters. A novel configuration of photonic crystal ring resonators(PCRRs)  based on optical channel drop filters (CDFs) with triangular lattice is proposed. The rods of this structure is silicon with the refractive index nsi=3.46 and the surrounding environment is air with the refractive index of nair=1. The widest photonic band gap obtains for the filling ratio of r/a = 0.2. The normalized transmission spectra of CDF are observed using Two- Dimensional-finite difference time domain (2D-FDTD) method. The photonic band gap (PBG) is calculated by plane wave expansion (PWE) method. The simulation shows, 100% dropping efficiency and suitable quality factor at 1534.5nm wavelength achieved for this filter. Also in this paper, we investigate parameters which have an effect on resonant wavelength and transmission spectra in this CDF, such as refractive index of inner rods and the refractive index of whole rods of the structure.  The area of the proposed structure is about 10.32μm × 10.32μm which is suitable for photonic integrated circuits and optical communication network applications. Manuscript profile

Photonic crystal ring resonators (PCRRs) are traditional structures for
designing optical channel drop filters. In this paper, Photonic crystal channel drop filter
(CDFs) with a new configuration of ring resonator is presented. The structure is made of
a square lattice of silicon rods with the refractive index nsi=3. 4 which are perforated in
air with refractive index nair=1. Calculations of band structure and propagation of
electromagnetic field through devices are done by plane wave expansion (PWE) and
finite difference time domain (FDTD) methods, respectively. The simulation shows,
100% dropping efficiency and suitable quality factor at 1592. 6 nm wavelength achieved
for this filter. Also, in this paper, we investigate parameters which have an effect on
resonant wavelength and transmission spectrum in this CDF, such as refractive index of
inner rods and whole of dielectric rods of the structure. The proposed structure is small
which is more suitable for used in the future photonic integrated circuits, wavelength
division multiplexing (WDM) systems and optical communication network
applications. Also, we suggested a heterostructure wavelength demultiplexer is
composed of four ring resonators. These ring resonators are located in four different
regions (heterostructure) which each region has specific dielectric constant. Manuscript profile