All-optical computing has drawn increased interest from researchers in recent years to meet the need for fast optical signal processing. This paper demonstrates the design of an all-optical CNOT logic gate using a silicon nitride (Si3N4) based optical ring resonator (ORR). Two optical ring resonators have been employed to design the CNOT logic gate. The simulation results obtained from MATLAB using the mathematical equations of the ring resonator validates the proposed CNOT logic gate. The proposed CNOT logic gate is compact and elementary.
The current work proposes an optimized design for 2-bit synchronous up counter using silicon nitride on insulator optical microring resonators (MRRs). The research involves exploring the existing designs of up counter structures based on MRRs, and then minimizing the number of rings being used in the proposed model. The proposed design uses four MRRs for Synchronous up counter operation and the model has been validated through the MATLAB simulation result. The main component of the design is the MRR which can act as a switch depending upon the output at the drop port or the through port according to the MRR being in an on-resonance or off-resonance state respectively. The principle of the MRR is that on applying a vertical pump signal over the ring, the non-linear refractive index of the ring undergoes a temporary blue shift resulting due to π- phase shift in the ring, changing the resonant frequency of operation of the ring. The average pump power required for the blue shift can be obtained from the phase shift vs. the average pump power graph simulated in MATLAB. This shift in resonance frequency is employed to switching action for the signal to be output at the drop port or the through port of the MRR and based on the drive signal inputs of the present state and the clock to the rings in the resonator structure which act as pump signal over the ring, the next state of the counter is determined.
KEYWORDS: Spatial light modulators, Orthogonal frequency division multiplexing, Transmitters, Modulation, Signal detection, Data transmission, Receivers, Wireless communications, Systems modeling, Telecommunications
Optical Wireless Communication (OWC) has the potential to offer a transmission link that is both dynamic and flexible in comparison to fiber optics communication. The optical spectrum exhibits a significantly greater range than the conventional Radio Frequency (RF) communication spectrum. Optical Orthogonal Frequency Division Multiplexing (OOFDM) can be treated as an integral part of OWC Systems. It is a modulation technique which refers to the implementation of OFDM in the Optical Domain. For the OFDM signal to be transmitted in the Optical domain, we perform Intensity Modulation/Direct Detection and for that the signal needs to be real and positive. In this paper, we have made the signal Hermitian symmetric along with IFFT and performed adaptive biasing to make the transmitting signal real and positive respectively. One of the major issues which still persists is the high Peak-to-Average Power Ratio (PAPR). To overcome this, we have implemented Selected Mapping (SLM), using Shapiro-Rudin Phase Sequences (SRPS). We have used SRPS as they yield a low crest factor, have good randomness, strong correlation, and help in reducing the average transmit power, which will eventually help in decreasing the complexity of the system. By performing Adaptively Biased Optical OFDM (ABO-OFDM) in conjugation with SLM we have been able to achieve a reduction of about 3 dB in the PAPR graph, without affecting the BER curve. Moreover, the increase in the system complexity is comparatively lower, or it can be stated that the increase is approximately halved.
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