Investigation of Ber Performances in Chaotic-Secured Optical Fiber Communication Systems using the 4-PAM Modulation Scheme

This paper presents a numerical simulation investigation on the bit error rate in a chaotic-secured fiber channel and a conventional fiber channel when propagating independently. The investigated communication system uses the pulse-amplitude modulation scheme (4-PAM) at the bit rate of 10 Gbps, the fiber length of 100 km, and the operation wavelength of 1550 nm. Our simulation results demonstrate both chaotic and non-chaotic transmission channels can well operate with the bit rate up to 20 Gbps with the BER smaller than 10-5 if dispersion and fiber loss issues are appropriately compensated without needing forwarderror-correction, showing high potential in physically secured optical fiber communication systems.

Key Distribution Scheme for Optical Fiber Channel Based on SNR Feature Measurement

With the increase in the popularity of cloud computing and big data applications, the amount of sensitive data transmitted through optical networks has increased dramatically. Furthermore, optical transmission systems face various security risks at the physical level. We propose a novel key distribution scheme based on signal-to-noise ratio (SNR) measurements to extract the fingerprint of the fiber channel and improve the physical level of security. The SNR varies with time because the fiber channel is affected by many physical characteristics, such as dispersion, polarization, scattering, and amplifier noise. The extracted SNR of the optical fiber channel can be used as the basis of key generation. Alice and Bob can obtain channel characteristics by measuring the SNR of the optical fiber channel and generate the consistent key by quantization coding. The security and consistency of the key are guaranteed by the randomness and reciprocity of the channel. The simulation results show that the key generation rate (KGR) can reach 25 kbps, the key consistency rate (KCR) can reach 98% after key post-processing, and the error probability of Eve’s key is ~50%. In the proposed scheme, the equipment used is simple and compatible with existing optic fiber links.

Hybrid NRZ/RZ line coding scheme based hybrid FSO/FO dual channel communication systems

<p><span id="docs-internal-guid-52ae510c-7fff-0f9d-c23b-ec77d8fd1141" style="font-size: 9pt; font-family: 'Times New Roman'; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">This </span><span id="docs-internal-guid-22aadf85-7fff-c447-0533-2748148ff46b" style="font-size: 9pt; font-family: 'Times New Roman'; color: #000000; background-color: transparent; font-weight: 400; font-style: normal; font-variant: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">study simulates the hybrid non return to zero (NRZ)/return to zero (RZ) line coding scheme based hybrid free space optics (FSO)/fiber optics (FO) dual channel communication systems. The max Q factor/Min BER are simulated after APD receiver based both erbium doped fiber amplifiers (EDFAs) and wide band traveling wave semiconductor optical amplifiers (WBTWSOAs) with 50 km fiber channel and 4 km FSO channel. Max SPAL/min noise SPAL, max signal power amplitude/min noise signal power variations with spectral frequency, and the total electrical power are demonstrated and clarified in this proposed study. This work emphasized that the fiber channel is reached up to 100 km reach and FSO channel can be also extended to 4 km reach with 40 Gbps.</span></p>

Spatial optical transceiver system–based key solution for high data rates in measured index multimode optical fibers for indoor applications

This study has simulated the spatial optical transceiver system based on measured index multimode optical plastic fibers channel with 1 Tb/s in 1.5 km distance. These plastic optical fibers are simply step index polycarbonate, step index polystyrene, step index polymethylmethacrylate, graded index polymethylmethacrylate and graded index cyclic transparent optical fiber (GI-CYTOP). Maximum Q-factor, optical signal power at optical fiber channel, receiver sensitivity, and coupling coefficient for sample of modes are measured based on GI-CYTOP fiber for the comparison between the previous model and the proposed model. This study clarified the enhancement of both maximum Q-factor and receiver sensitivity even though at high signal losses. The optimized Q-factor and receiver sensitivity are obtained for various plastic optical fiber channels. Power intensity level of dominant mode–based GI-CYTOP fiber channel is measured. The proposed model has presented better performance based on GI-CYTOP fiber channel in maximum Q-factor, which is within the percentage ratio ranging from 45.65 to 53.26%, optical signal power is within the percentage ratio ranging from 32.87 to 44.77%, and receiver sensitivity is within the percentage ratio ranging from 6.3 to 12.26% than the previous model at transmission distance ranges from 500 to 1500 m and bit rate of 2.5 Gb/s. GI-CYTOP fiber clarified better performance in maximum Q-factor and receiver sensitivity response better than other plastic optical fibers channels.