Gray codes are broadly used as the cyclic codes to assist error correction in optical communications. In this paper, we have proposed the novel design of three different types of all-optical gray code converters based on the semiconductor optical amplifier (SOA) Mach–Zehnder interferometer (MZI) configuration. The XOR and OR gates are the basic devices used for the proposed design of binary to gray, binary-coded decimal (BCD) to gray, and octal to binary code converters. For the first time, to the best of the authors’ knowledge, a high data rate of 500 Gbps is achieved for the three types of all-optical code converters using the SOA-MZI configuration by exploiting an M-ary differential phase shift keying (DPSK) modulation scheme. The performance factors of the proposed all-optical code converters like extinction ratio, bit error rate, and quality factor are calculated.
Future communication networks require the entire communication system to be all-optical to overcome the bandwidth constraints of electronics. All-optical devices play a vital role in supporting future networks, which demand a high speed of up to Tbps. An all-optical gray code converter operation was demonstrated numerically using a photonic crystal semiconductor optical amplifier (PhC-SOA) in a Mach-Zehnder interferometric (MZI) configuration at 1 Tbps for M-ary differential phase shift keying modulated binary and BCD inputs. The design achieved a very high extinction ratio of about 123.8 dB with a good quality factor value of about 45. The results show that PhC-SOA-based XOR and OR gates in the gray code converter design exhibits improved modulation features compared with traditional SOAs in our previous works.
Most major high-speed applications, such as communications, environmental monitoring, transportation, smart homes, industries and gadgets are enabled by
recent photonic technology. Basic all-optical logic gates are used in the development of
image sensors, ultra-fast optical devices, and positioning equipment in high-speed
applications. Among different technologies proposed for all-optical implementation,
Semiconductor Optical Amplifiers (SOA) have been widely adopted. They have
attractive features such as wide gain bandwidth, low power consumption, compactness
and strong non-linearity. SOA still has a limitation that its spontaneous emission noise
restricts the performance. The semiconductor optical amplifiers with quantum dots
exhibit higher saturation output power, lower current density threshold, wider gain
bandwidth, and low noise figure than conventional SOA. Quantum Dot Semiconductor
Optical Amplifiers (QDSOAs) also have limitations like large size, high power
consumption and spontaneous emission of noise. Photonic Crystal (PhC) is an artificial
material that is suitable to overcome all drawbacks of SOA and QDSOA due to its
simple structure and compactness, high speed, low power consumption, and low loss.
PhC-based structures allow propagation of light in a controlled manner with its
periodic crystal arrangements having dissimilar diffraction index. PhCs are considered
to be a suitable structure for designing all-optical devices with compactness. In this
chapter, an all-optical XOR is designed. Initially, the XOR gate is designed and
simulated by using the FDTD method. The proposed XOR logic is achieved without
nano-resonators and then with nanoresonators to get enhanced performance metrics in
the form of high contrast ratio. The contrast ratio is 260 dB for the XOR gate with a
delay time of 0.19 ps. The proposed XOR logic gate has potential practical applications
for high speed applications of telecommunication systems.
Advanced modulation format is a promising solution to accomplish improved bandwidth exploitation for quality transmission in optical networks. This paper proposes a modified duobinary modulation in an optical communication network, and the proposed system is compared with the preceding modulation scheme of duobinary modulation without a precoder and duobinary modulation with a precoder. Ideally, two or more signals are transmitted over single-mode fiber using a multiplexing method. Hence, wavelength division multiplexing (WDM) using an erbium-doped fiber amplifier (EDFA) as an active optical network is utilized to improve the quality factor and reduce the effect of intersymbol interference in optical networks. The performance of the proposed system is analyzed for parameters such as quality factor, bit error rate, and extinction ratio using OptiSystem 14 software.
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