Method of implementation of all-optical frequency encoded logic operations exploiting the propagation characters of light through semiconductor optical amplifiers

Abstract

Optics has already proved its strong potentiality for conducting parallel logic, arithmetic and algebraic operations. Since last few decades so many all-optical data processors were proposed. To implement these processors different encoding / decoding techniques, such as polarization encoding, intensity encoding, phase encoding technique have been reported. Very recently 'frequency encoding' technique have drawn a special interest to the scientific community. The frequency is the fundamental character of a signal and it preserves its identity irrespective of reflection, refraction, transmission, absorption throughout the communication. Therefore, if two specific frequencies are encoded as 1 state and 0 states respectively, then one can ensure about the state of information throughout the communications. In this paper the authors propose a method of conducting inversion OR, NOR and NAND logic operations exploiting the wavelength conversion, which is achieved by exploiting the cross gain modulation (XGM) property of reflecting semiconductor optical amplifier (RSOA), as well as the property of change of nonlinear rotation of the state of polarization of probe beam by cross phase modulation (XPM). Both the wavelength conversion properties are controlled by the intensity of the pump beam. The major advantage of SOA-switching over any other conventional switching is that SOA-switching require low power with good on off contrast ratio. Again as the NAND and NOR are the universal logic gates, so any other logic operation can be implemented using this concept.

A Novel Method of Developing Frequency Encoded Different Optical Logic Processors Using Semiconductor Optical Amplifier

“…The block diagram of frequency encoded different logic units with proper distribution of probe beams X1( 1  ) and X2( 2  ) in four probe beam terminals of SOA units i.e., SOA1, SOA2, SOA3 and SOA4, designated by 1,2,3 and 4 respectively are as shown in Fig.4. The above mentioned scheme may be extended to design all optical multiplexer and demultiplexer [Garai S.K., Mukhopadhyay S.(2009)], data comparator multivalued logic unit such as trinary [Garai S.K., 2010], quaternary etc. logic gates and all optical arithmetic logic unit [Garai S.K.(2011c)].…”

A scheme of developing frequency encoded tristate-optical logic operations using semiconductor optical amplifier

“…The input data signal, which may be of frequency 1 / 2 / 0 , can be directed to separate paths using 'AD' (optical add/drop multiplexer) [15,16,[20][21][22][23]. The function of a wavelength AD is to separate a particular wavelength channel without interference from adjacent channels.…”

“…All these encoding techniques have their limitations. Very recently, frequency encoding/decoding techniques have also become well established [13][14][15]. Frequency is the fundamental character of any signal and it remains unaltered in reflection, refraction, absorption etc.…”

“…Thus, using frequency encoding it is easier to represent a multi-bit logic unit and at the same time to implement multivalued logic operations using high wavelength conversion properties of SOAs. We have already developed a scheme of frequency encoded inversion operation with tristate logic [15]. In this paper the author proposes a method of implementing AND, NAND, OR and NOR operations with tristate logic adopting the frequency encoding technique.…”

“…The truth tables for frequency encoded AND, OR, NAND and NOR operations with tristate logic are shown respectively in Tables 1-4. To implement the desired logic operations optical beams having different frequencies in C-band are used exploiting the nonlinear rotational character of the state of polarization of the probe beam of a semiconductor optical amplifier (SOA) [16][17][18][19] as well as the frequency routing property of semiconductor optical amplifiers (add/drop multiplexer) [15,16,[20][21][22][23]. To achieve a better extinction ratio, the signal induced nonlinearities in the bulk semiconductor optical amplifier have been exploited.…”