Āsansol, India
Āsansol, India

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Optics has an important role in logic implementation and computation is established in two and half decades by many researchers. Recently frequency encoding technique is established. This technique does not suffer from intensity dependent loss problems like other schemes. Amorphous dielectric thin films with reflecting edges can also be used for logic realization and has very fast response speed. It also does not use any semiconductor device and simple to construct. In this communication the authors have proposed all optical CNOT gate using frequency encoded difference frequency generation exploiting nonlinear response of some material and implementation of binary adders by CNOT gate and dielectric thin film AND gate. © 2009 Elsevier GmbH.


A frequency encoded all optical N bit comparator is proposed. The implementation is ultrafast one and the frequency encoding makes it intensity loss dependent problem free. The use of polarization insensitive four wave mixing makes the design polarization independent and the hardware simple. The frequency conversion by the RSOA makes the design faster compared to other SOA based design. The required gates, i.e. X-OR and AND gates for the implementation of the comparator in frequency encoded format are also discussed. © 2011 Elsevier GmbH.


A memory unit is a sequential logic which is an essential part of a computational machine. Realization of fast optical memory units is very challenging. In this communication the authors propose a method of implementation of different frequency encoded flip flops JK, D and T exploiting semiconductor optical amplifier based polarization rotation, filtering and frequency conversion. The main advantage of the frequency encoding technique is that it is free from intensity loss dependent problem and provides ultra fast speed of operation. © 2012 Optical Society of India.


All optical signal processing has capability of handling huge amount of data. This has become possible by the use of multi-valued logic in place of binary logic. In this communication a frequency encoded tri-state logic gates NOT, AND and NAND are proposed for the first time using difference frequency generation in non-linear materials. The operating principle of the logic gate is the difference frequency generation which is purely an optical phenomenon where no electrical energy is required. So it has greater speed of operation and uses less power. The state of information is represented by three different frequency conditions which have due advantage compared to other kind of encoding technique commonly used. © 2012 Elsevier GmbH. All rights reserved.


Optical adder/subtractor for two four-bit frequency encoded binary numbers are proposed and designed based on four wave mixing, add drop multiplexing and frequency conversion in semiconductor optical amplifier. The input bits and the control input are intensity-modulated signal of two specific frequencies suitable for optical communication in the C band of wavelength. The device can distinguish negative and positive results and controlled operation are most promising in this proposal. The use of semiconductor optical amplifiers along with frequency encoding makes the system very fast and useful for future optical communication and computation systems. © 2014 Elsevier GmbH. All rights reserved.


All optical logic gates exploiting polarization independent four wave mixing in semiconductor optical amplifier (SOA), filtering property of ADD/DROP multiplexer (ADM) and non-linearity in reflective semiconductor optical amplifier (RSOA) have been proposed. The logic gates proposed are polarization independent which ensures hardware simplicity and greater speed. The all optical frequency encoded logic gates NOT, OR, NOR, AND, NAND, X-OR, X-NOR are implemented which are very useful in optical computing ad signal processing, cryptography, etc. The logic gates proposed have the advantages that there is no intensity loss dependent problem, and are polarization and temperature insensitive. © 2010 Elsevier GmbH.


A novel hybrid encoding technique scheme is proposed. Using this technique and difference frequency generation different all optical logic gates NOT, OR, AND, NAND, NOR, and X-OR are realized. © 2010 Elsevier GmbH. All rights reserved.


A novel frequency encoded all optical half adder, half subtractor and full adder are proposed. The implementation is ultrafast one and the frequency encoding makes it intensity loss dependent problem free. The use of polarization insensitive four-wave mixing makes the design polarization independent and the hardware simple. The frequency conversion by the reflective semiconductor optical amplifiers (RSOA) makes the design faster compared to other semiconductor optical amplifiers (SOA) based design. © 2010 Elsevier GmbH. All rights reserved.


A novel method of implementation of frequency encoded logic gates NOT, OR, AND, NOR, NAND, X-OR, X-NOR is discussed. The frequency sources and physical requirements for the implementation are also discussed. The non-linear material (liquid) suitable for these operations to be performed should be of large non-linear coefficient, high reverse saturation absorption, large thermo-optic coefficient and low viscosity. The input controlling beams used to induce non-linearity in the switch are either of frequency υ 1 or υ 2 and the probe beam is a mixed signal of frequencies υ 1 and υ 2. Depending on the nature of the controlling inputs the output conditions of the probe can be adjusted to get different logic gates. © 2010 Elsevier GmbH. All rights reserved.


All optical encryption decryption method using frequency encoding is proposed based on semiconductor optical amplifiers. The plain text and key are encoded in frequency encoding format i.e. the states of information '0' and '1' are represented by two different frequencies in the c-band. The ultra fast speed of operation of the devices used for the implementation of this system makes it very attractive for future all optical secure communication network. A simple method of conversion of frequency encoded data stream and intensity encoded data stream is also described, which enables us to use same technology of production and detection of intensity encoded data signals until new techniques based on frequency encoding comes out. © 2010 Elsevier GmbH. All rights reserved.

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