Overview of an all-optical analog-to-digital converter, focusing of deflected TeraHertz optical pulse and propagation characteristics

摘要

The Advanced Radars and Electro-Optical Sensors group at the University of Missouri is constructing a new all-optical analog-to-digital converter (ADC) platform. This integrated optics application especially suits the data acquisition and processing requirements of mobile sensor systems that have dramatically increased alongside the requirements for reductions in system mass, volume, and power consumption. The platform of the ADC is composed of a direct-modulated laser (DML) at λ = 1.55 μm with a 40 G bits/sec sampling optical pulse source; a prism LiTaO_3 (lithium tantalate) electro-optical deflector; an integrated focusing unit; a three-dimensional binary-coded spatial filter array; and collection optics. Using discrete Fourier transform, we also investigate both the center frequency-shifting phenomenon of the optical pulse propagation, and the frequency response. The simulations are calculated by using the two-dimensional Finite Difference Time Domain (FDTD) method, the results of which are much more reliable than Beam Propagation Methods (BPM). The spatial filter array and collection optics will be fabricated by the separated implanted oxygen process (SIMOX), silicon on insulator (SOI). Also, a new design and simulation of electro-optical deflector to be integrated in the same substrate is proposed. This platform is to be tested for 50 Giga-samples/sec analog-to-digital conversion, and be the prototype of a 100 Giga-samples/sec ADC.