en نانوفوتونیک و ساختارهای نانویی Nanophotonics and Nanostructures پژوهشي Research <span style="font-size:medium"><span new="" roman="" style="font-family:" times=""><span style="color:#000000"><span style="font-style:normal"><span style="font-weight:400"><span style="white-space:normal"><span style="text-decoration:none"><b><span style="font-size:11pt">In this paper, a structure is proposed using ring resonator created on 2D photonic crystal (PC) that acts as an add-drop filter (ADF) in all-optical communication systems. The same structure can also act as refractive index (RI) and temperature sensor. The structure is made up of a hexagonal lattice of air holes in a dielectric slab of silicon with the refractive index of 3.46. The band diagram of the considered structure is obtained using plane wave expansion (PWE) method, and optical propagation through it is simulated using finite difference time domain (FDTD) method. The computational analysis is performed on different structural and physical parameters. Transmission efficiency, quality factor and bandwidth are investigated by varying (i) lattice constant (ii) radius of holes of different parts of the structure and (iii) refractive index of different parts of the structure. The chosen parameters result in operating wavelength around 1550 nm. The designed ADF has a footprint of only 68&micro;m² and a dropping efficiency of 100%. The sensitivity of the structure is determined by determining shifts in the resonance wavelength as a function of the RI of the holes/slab. The designed structure exhibits desirable features like (i) narrow bandwidth of 1.5 nm, (ii) high-quality factor of 1033, (iii) low detection limit of 3.6</span></b><b><span style="font-size:11pt"><span style="font-family:Symbol">&acute;</span></span></b><b><span style="font-size:11pt">10^-4 RIU, (iv) high RI sensitivity of 407&nbsp;nm/RIU, and (v) high temperature sensitivity of 104 pm/K.</span></b></span></span></span></span></span></span></span> Photonic Crystal, Finite Difference Time Domain Method, Plane Wave Expansion Method, Add-Drop Filter. 221 232 http://ijop.ir/browse.php?a_code=A-10-928-1&slc_lang=en&sid=1 Sarang Medhekar smedhekarbit@gmail.com 10031947532846004684 10031947532846004684 Yes Department of Physics, Central University of Jharkhand, Ranchi, India Puja Sharma pujaranchi691@gmail.com 10031947532846004685 10031947532846004685 No Department of Physics, Central University of Jharkhand, Ranchi, India Man Mohan Gupta man_manna@yahoo.com 10031947532846004686 10031947532846004686 No Department of Physics, Tata College Chaibasa, West Singh Bhum, India Nilaksha Ghosh nilakshaghosh@gmail.com 10031947532846004687 10031947532846004687 No Department of Physics, Central University of Jharkhand, Ranchi, India