Applications and Performance of Optical Analog-to-Digital Converter and Optical Logic Gate Elements in Multilevel Multiclass Fiber-Optic CDMA Systems

In this paper, we present and analyze a novel all-optical multilevel multiclass optical code division multiple access (OCDMA) system, using optical analog-to-digital converter (ADC) and advanced optical logic gate elements. In such OCDMA network, users are distributed in M different classes. Furthermore, power level with which users in class j, j = 2, ..., M, transmit optical pulses, is twice the power level at which users of class j - 1 transmit their optical pulses. We achieve optical transmitter structure that satisfies these conditions using power control schemes. Also, we suggest two receiver structures for the aforementioned multiclass multilevel system. The first and simple receiver structure is based on optical AND logic gate elements. The second structure uses an optical ADC as well as optical AND logic gates. We obtain the performance for the aforementioned two types of receivers and compare their results with the traditional one-level OCDMA system. We show that using the proposed multilevel multiclass scheme improves system performance considerably by means of decreasing error probability as well as increasing the network capacity.