TOAD-Based Frequency-Encoded All
Optical XOR Gate, Half Adder, and Half
Subtractor
Kousik Mukherjee, Kajal Maji, Ashif Raja, and Mrinal Kanti Mandal
Abstract Tera Hertz Optical asymmetric Demultiplexer or TOAD is an important
optical switch in optical computational and communication applications. It is used
to design different types of logic gates and logic circuits. In this chapter, we have
utilized it to design a frequency-encoded optical XOR gate, half adder, and half
subtractor using TOAD-based switch for the first time. The input/output bit patterns
along with ON/OFF ratio is also investigated.
Keywords TOAD · Frequency encoding · XOR gate · Half adder · Half subtractor
1 Introduction
Semiconductor amplifiers (SOAs) are important modules for the realization of
next-generation optical network [1]. Many proposals for frequency-encoded all
optical logic gates and circuits have been implemented using SOA-based nonlinearities like cross-gain modulation (XGM), cross-phase modulation (XPM), four
wave mixing (FWM), polarization rotation, etc. [2–8]. Frequency encoding uses two
different frequencies ν 1 and ν 2 for representing ‘0’ and ‘1’, respectively. Conventional encoding has many drawbacks compared to frequency encoding technique like
intensity dependence, or polarization dependence, etc. This is because frequency is a
characteristic of light that remains unchanged in reflection or transmission [2]. TOAD
is an important interferometric device for the implementation of optical logic processors at high speed [9, 10]. Recently, TOAD is utilized to design optical frequencyencoded logic gates by us in [10]. In this present chapter, frequency-encoded X-OR
gate, half adder, half subtractor are designed and analyzed using TOAD as switch for
K. Mukherjee (B) · K. Maji · A. Raja
Department of Physics, B.B. College, Asansol, India
e-mail: klmukherjee003@gmail.com
K. Mukherjee · A. Raja
Centre of Organic Spintronics and Optoelectronics Devices, KNU, Asansol, India
K. Maji · M. K. Mandal
Department of Physics, National Institute of Technology Durgapur, Durgapur, India
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. Biswas et al. (eds.), Emerging Trends in Terahertz Engineering and System
Technologies, https://doi.org/10.1007/978-981-15-9766-4_9
177
Optical XOR Gate, Half Adder, and Half
Subtractor
Kousik Mukherjee, Kajal Maji, Ashif Raja, and Mrinal Kanti Mandal
Abstract Tera Hertz Optical asymmetric Demultiplexer or TOAD is an important
optical switch in optical computational and communication applications. It is used
to design different types of logic gates and logic circuits. In this chapter, we have
utilized it to design a frequency-encoded optical XOR gate, half adder, and half
subtractor using TOAD-based switch for the first time. The input/output bit patterns
along with ON/OFF ratio is also investigated.
Keywords TOAD · Frequency encoding · XOR gate · Half adder · Half subtractor
1 Introduction
Semiconductor amplifiers (SOAs) are important modules for the realization of
next-generation optical network [1]. Many proposals for frequency-encoded all
optical logic gates and circuits have been implemented using SOA-based nonlinearities like cross-gain modulation (XGM), cross-phase modulation (XPM), four
wave mixing (FWM), polarization rotation, etc. [2–8]. Frequency encoding uses two
different frequencies ν 1 and ν 2 for representing ‘0’ and ‘1’, respectively. Conventional encoding has many drawbacks compared to frequency encoding technique like
intensity dependence, or polarization dependence, etc. This is because frequency is a
characteristic of light that remains unchanged in reflection or transmission [2]. TOAD
is an important interferometric device for the implementation of optical logic processors at high speed [9, 10]. Recently, TOAD is utilized to design optical frequencyencoded logic gates by us in [10]. In this present chapter, frequency-encoded X-OR
gate, half adder, half subtractor are designed and analyzed using TOAD as switch for
K. Mukherjee (B) · K. Maji · A. Raja
Department of Physics, B.B. College, Asansol, India
e-mail: klmukherjee003@gmail.com
K. Mukherjee · A. Raja
Centre of Organic Spintronics and Optoelectronics Devices, KNU, Asansol, India
K. Maji · M. K. Mandal
Department of Physics, National Institute of Technology Durgapur, Durgapur, India
© The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021
A. Biswas et al. (eds.), Emerging Trends in Terahertz Engineering and System
Technologies, https://doi.org/10.1007/978-981-15-9766-4_9
177