Full optical 2-bit analog to digital convertor based on nonlinear material and ring resonators in photonic crystal structure

In this paper, a new structure for optical analog to digital convertor (OADC) based on Kerr effect is proposed. Sampling and quantizing have been done at central wavelength lambda = 1550 nm by two ring resonators and three nonlinear rods which are located inside the waveguide. A pillar-based square lattice of a 2DPhC is made of linear material Si0.75Ge0.25 with n(SiGe) = 3.6 implemented in the air background. By choosing a type of glass with n(0) = 1.4 as inner rods that is used inside ring resonator, Power loss and transmission efficiency have been improved. Nonlinear part of structure is designed by three rods whose nonlinear refractive is n(2) = 10(-17) m(2)/W. The performance of the OADC structure is simulated by means of finite difference time domain (FDTD) method. The proposed structure is able to support maximum sampling rate up to 300 GS/s and total footprint is about 240 mu m(2). Resolution Sampling Rate Product is 1200 KS.