A novel approach for all-optical digital encoder for both binary-to-gray code and gray-to-binary code have been proposed. Design is based on the basic concept of digital encoder using the exclusive OR (XOR) addition. The XOR gate used in these encoders has been implemented using differential phase modulation between two arms of the Mach-Zehnder interferometer (MZI), in which a semiconductor optical amplifier is placed symmetrically in both arms of MZI. For the most severely degraded output bit, i.e., least significant bit for gray-to-binary encoder, the extinction ratio obtained is 2.35 while the minimum bit error rate is zero at 10 GB/s . For the second most significant bit of gray-to-binary encoder and for all the three bits except the most significant bit of binary-to-gray encoder, the extinction ratio obtained is around 27 dB. For the most significant bit, as input and output bits are same, the extinction ratio is very high, approaching infinity.
In this paper an all-optical exclusive OR (XOR) gate is proposed, which uses an integrated semiconductor optical-amplifier based Mach-Zehender interferometer. The design works on differential phase modulation scheme and the operation of the proposed gate is verified up to 120 Gb/s. Results of the gate has been analyzed in time domain for different input bit sequences. Highest extinction ratio of 26.01 dB is noted at 80 Gb/s. Rate analysis is also performed to optimize the Quality factor and a bit error rate.
Increasing communication traffic and plans to increase various services may cause a serious problem towards the power consumption of network equipment. One of the causes of large power consumption in the present network is the multiplexing scheme, such as wavelength division multiplexing (WDM) and electrical routing of the packet signals. WDM requires O/E (optical to electrical) and E/O (electrical to optical) signal conversion circuits with the same number as that of wavelength, resulting in an increase in power consumption. In addition to this electrical signal processing for the IP packet, routing, and switching at the router consumes a large amount of power. If we could process ultrafast signals using electromagnetic light waves without converting to electrical signals, this would reduce the power consumption of routers. One of the ways to overcome these problems is the development of all-optical computing devices. All-optical computing devices are based on the nonlinear interaction of light waves, which is an electromagnetic wave. The use of electromagnetic light waves makes computing, such as switching, possible at very high frequencies of more than 100 GHz. We discuss all-optical computing devices based on semiconductor optical amplifiers with the main emphasis on all-optical logic gates.