Optical Universal Logic Gates based on Electro-Optic Effect
of Lithium Niobate in Mach-Zehnder Interferometer
1,2
Santosh Kumar1, Ashish Bisht2, Angela Amphawan3
Photonics Lab, Department of Electronics & Communication Engineering, DIT University, Dehradun, Uttarakhand, 248009, India
3
InterNetWorks Research Laboratory, School of Computing, Universiti Utara Malaysia, Sintok, Kedah, 06010, Malaysia
e-mail: 1santoshrus@yahoo.com,2mail2ashishbisht@gmail.com, 3angelaoptics@gmail.com
Abstract: The paper demonstrates newly proposed optical universal logic gates which can be used
as a basic building block in digital optical computers. The simulation results are provided through
MATLAB and Beam propagation method.
Keywords: Optical logic devices; Optical logic; Optical logic devices
1. Introduction
Optical logic gates are the key components in optical combinational and sequential digital systems which take
advantage of the propagation of light to accomplish logic functions [1–3]. Optical logic gates have potential
applications for bit-error monitoring [4], address and payload separation [5]. Researchers have shown their interest
in implementing optical XOR, OR and universal logic gates by using SOA-MZIs [6]. But the response time of gain
saturation of a SOA-MZI limits its operation.
In this paper the optical universal logic gate operation and a novel design is demonstrated using minimum
number of LiNbO3 based MZIs, which reduces the complexity of optical circuits at great extent. The scheme
depends on the electro-optic effect based MZI structures which provides very high data rates [7]. Also, utilizing at
appropriate operating points low cross talk, high extinction ratio, low transition losses can be achieved [8].
2. Design and Working
Figure 1(a) shows the schematic diagram of the proposed NOR gate using two MZIs. An optical signal is given to
the first input port of MZI1. The second output port of MZI1 is connected to the second input port of MZI2. The
first output port of MZI2 (Output Port 2 in Fig. 1(a)) is the output port of interest and provides the output of the
NOR logic gate. For proper switching of the optical signal, voltage signal X and Y are applied at the second
electrode of MZI1 and MZI 2 respectively. The OptiBPM layout of NOR gate is shown in Fig. 2 (a).
Fig. 1. (a) Schematic diagram of NOR gate using MZIs (b) Schematic diagram of NAND gate using MZIs.
Three MZIs are required to implement the NAND gate as shown in Fig. 1 (b). The optical signal is provided to
the first input port of MZI1 and MZI2. The second output port of MZI1 is connected to the first input port of MZI3
and the second output port of MZI 2 is connected to the second input port of MZI3. Here, the first output port of
MZI3 (Output port 2 in Fig. 1 (b)) is acting as the output of NAND logic gate. For proper switching of the optical
signal, voltage signal X is applied to the second electrode of MZI1 and voltage signal Y is applied to the second
electrode of MZI2 and MZI3 respectively. The OptiBPM layout of NAND gate is shown in Fig. 2 (b).
Fig. 2. (a) Layout diagram of NOR gate using MZIs (b) Layout diagram of NAND gate using MZIs.
3. Simulation Results and Discussion
The MATLAB simulation results for the optical NOR and NAND logic gates are shown in Fig. 3 (a) and in Fig. 3
(b) respectively. The possible combinations of input signal X and Y are represented in first and second row
respectively. The output of the optical logic gate is represented in third row.
Fig. 3. (a) MATLAB simulation result of NOR gate (b) MATLAB simulation result of NAND gate.
OptiBPM is further used to analyze the proposed structure. The OptiBPM simulation results for the optical NOR and
NAND logic gates are shown in Fig. 4 (a) and in Fig. 4 (b) respectively. In the case of optical NOR gate, optical
signal is obtained at first output port of MZI2 only when both the input signal X and Y attains 0 electrode voltages.
Whereas in case of NAND gate, optical signal is not obtained at first output port of MZI3 only when both the input
signal X and Y attains 6.75 electrode voltages. Here, electrode voltage 0V and 6.75V is considered as logic ‘0’ and
logic ‘1’ for the proposed device respectively [6].
Fig. 4. (a) OptiBPM simulation results for optical NOR gate operation (b) OptiBPM simulation results for optical NAND gate operation.
4. Conclusion
The optical NOR and NAND gate logic operations have been implemented using the cascaded MZI structures based
on electro-optic effect of lithium niobate. The schematic and layout diagrams are provided. The results are obtained
using the MATLAB simulation and verified through Beam Propagation Method.
5. References
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
J. Hardy and J. Shamir, “Optics inspired logic architecture,” Opt. Express 15 (1), 150–165 (2007).
H. J. Caulfield, R. A. Soref, and C. S. Vikram, “Universal reconfigurable optical logic with silicon-on-insulator resonant structures,”
Photonics Nanostruct. Fund. Appl. 5 (1), 14–20 (2007).
H. J. Caulfield and S. Dolev, “Why future supercomputing requires optics,” Nat. Photonics 4 (5), 261–263 (2010).
L. Y. Chan, K. K. Qureshi, P. K. A. Wai, B. Moses, L. Lui, H. Y. Tam, and M. S. Demokan, “All-optical biterror monitoring system using
cascaded inverted wavelength converter and optical NOR gate,” IEEE Photon. Technol. Lett. 15 (4), 593–595 (2003).
C. Bintjas, N. Pleros, K. Yiannopoulos, G. Theophilopoulos, M. Kalyvas, H. Avramopoulos, and G. Guekos, “All-optical packet address
and payload separation,” IEEE Photon. Technol. Lett. 14 (12), 1728–1730 (2002).
J-Y. Kim, J-M. Kang, T-Y. Kim, and S-K. Han, “All optical multiple logic gates with XOR, OR, NOR and NAND functions using parallel
SOA-MZI structures: Theory and experiment,” J. Lightw. Technol. 24 (9), 3392-3399 (2006).
Santosh Kumar, Gurdeep Singh, Ashish Bisht, “4x4 Signal Router based on electro-optic effect of Mach-Zehnder Interferometer for
wavelength division multiplexing applications,” Optics Comm. 353, 17-26 (2015).
A. Kumar, Santosh Kumar, S. K. Raghuwanshi, “Implementation of full-adder and full-subtractor based on electro-optic effect in Mach
Zehnder interferometer,” Optics Comm. 324, 93-107 (2014).