All-optical logic gates (AO-LGs) are the key elements that play a pivotal role in the development of future all-optical networks and all-optical computing. A complete overview of the seven all-optical logic gates (i.e., AND, OR, NOT, XOR, XNOR, NAND, and NOR) based on their design techniques and applications are covered, including the latest technologies, such as topological photonics and artificial intelligence-based designs techniques. In addition, we have further categorized the AO-LGs as reconfigurable gates, simultaneous gates, reversible gates, modulation-based gates, and data rate-based gates. The techniques to implement these different classes of gates are reviewed and their limitations are discussed. We also discuss in brief the various simulation tools used to design and analyze the AO-LGs. Finally, the most feasible techniques for constructing optical integrated circuits based on the existing fabrication technologies and available resources are explored, and future prospects are outlined.
In this work, an optimized structure of an XOR gate working in the optical domain is put for-ward to achieve high contrast ratio and extremely compact dimensions using a photonic crystal platform. The above structure employs silicon rods in a hexagonal lattice configuration. The design works purely on linear interference effect between the incoming light signals and does not involve any non-linear materials. The Finite Difference Time Domain based simulations are utilized to study the propagation of light within the structure and the Plane Wave Expansion Method is applied to generate bandgap structure. After optimization of the various design parameters, a contrast ratio of 31.76 dB is attained by the proposed structure along with a response time of 0.46 ps and a footprint of 42.24 μm 2 . The device can be operated in the C Band with optimum performance at 1550 nm, which is the telecommunication wavelength. The operating bit rate for the proposed structure is 2.17 Tbps. All-optical XOR gate being a universal gate forms the building blocks of various sequential and combinational logic designs suitable for optical computing and communication applications.
Abstract. The next generation Photonic Integrated Circuit (PIC) make use of optical power divider for achieving high operating speeds in the field of optical communication. A Wilkinson power divider is designed using 2D Photonic Crystal in this paper. Wilkinson power divider is three port network which is lossy. But when the output ports are matched, it has unique property of becoming losslesss. The divider also achieves isolation between output ports. The power dissipated is from the power that is reflected. The propagation of wave and photonic band gap were obtained by Finite-difference Time-Domain (FDTD).The designed structure has a resonant wavelength of 1550 nm. The simulation is performed using Opti FDTD software. For the two port Wilkinson power divider 55.4% of input power was coupled at the output. For the 4 port 55% of input power was coupled at the output port.
Photonic crystal based designs of 3-bit even parity checker and
generator circuits are proposed in this paper. These circuits are
realized for the first time, to the best of our knowledge, on a
photonic crystal platform with the aim of achieving power efficient,
simple, and compact devices suitable for photonic integrated circuits.
The proposed structures are realized using all-optical reconfigurable
XOR/NOT gates with compact dimensions, low power consumption, and high
contrast ratios. The operation is based on a linear interference
effect leading to reduced power consumptions feasible for operation in
the telecommunication wavelength of 1550 nm. The various
performance metrics such as contrast ratio, response time, and data
rate are analyzed based on simulations using the finite difference
time domain technique. All structures achieve small footprints and low
response times with operation speeds up to 1 Tbps. The designs are
based purely on silicon material, which enables ease of fabrication
and offers easy compatibility with existing opto-electronic systems as
well as with upcoming all-optical systems. The above circuits have
wide applications in optical computing, error correction, detection,
and optical cryptography.
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