High performance of an all-optical two-bit analog-to-digital converter based on Kerr effect nonlinear nanocavities.

Abstract

In this paper, a new configuration for an all-optical analog-to-digital converter based on nonlinear materials has been proposed. This structure is the combination of two main parts: a quantization block followed by an optical coder. The refractive index of the nonlinear composite material varies with the intensity of the optical field. Sampling and quantizing have been performed at central wavelength $\lambda = {1550}\;{\rm nm}$λ=1550nm by three ring resonators that are filled by nonlinear material AlGaAs with linear refractive index of ${n_1} = {1.4}$n1=1.4 and Kerr index of ${{n}_2} = {1.5} \times {{10}^{ - 17}}\;{{\rm m}^2}/{\rm W}$n2=1.5×10-17m2/W. The maximum sampling rate is 260 GS/S. The sampling accuracy of the structure is 1040 KS. The overall area of the structure is ${{540\,\,\unicode{x00B5}{\rm m}}^2}$540µm2. The fast plane wave expansion method is used in the band structure calculations and the two-dimensional finite-difference time-domain method is used to calculate the transducer transmission spectrum, their resonant frequencies and quality coefficients, and the transducer output power at single wavelengths and constant intensities.