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This interdisciplinary research is focused on constructing and demonstrating enhanced-reach polarization optical time-domain reflectometer (POTDR) for monitoring single-mode fibre optical communication lines. An optical signal state of polarization measurements enables several new possibilities for real-time monitoring solutions in fibre optics. However, there is no commercial equipment available to determine the location in fibre optical cable where the light polarization state changes. The authors present a monitoring technique of an optical signal state of polarization based on reflected signal time-amplitude analysis with improved operation parameters, namely, timing resolution (2 to 3 ps RMS) and amplitude measurement resolution of nanosecond scale pulses (8 to 10 bits) for monitoring of fibre optical communication lines. Additionally, the demonstrated POTDR provides a considerable optical fibre line measurement reach of up to 40 km. [ABSTRACT FROM AUTHOR]

Four-wave mixing optical frequency comb fibre-based setups (FWM-OFCs) have the potential to improve the combined dense wavelength division multiplexed passive optical network (DWDM-PON) and fibre Bragg grating (FBG) temperature sensors network providing easier application, broader technological opportunities for network development, and energy efficiency by substituting a power-demanding laser array. In this research, OFCs are generated for the purpose of combined network application of DWDM-PON and FBG optical sensors. The paper also investigates compatibility scenarios with OFCs in such systems. The mathematical simulation model has been developed and the performance of FWM-OFC based 8-channel 50 GHz spaced non-return-to-zero on-off keying (NRZ-OOK) modulated DWDM-PON transmission system, operating at 50 km single-mode fibre (SMF) with a bit rate of at least 10 Gbps embedded with 7 FBG optical temperature sensors, has been studied. As it is shown, FWM application results in OFC source that has fluctuations of the individual comb tones of less than 3 dB in power, and with an extinction ratio of about 33 dB for operation range of 192.9–193.25 THz, acting as a unified light source for all the data transmission channels. Embedded FBG optical sensors network causes negligible 0.3 dB power penalty. [ABSTRACT FROM AUTHOR]

As the demand for fiber optical data transmission systems and other type of applications, which require optical media, like optical sensing increases, the unauthorized parties are becoming increasingly interested in such systems. Also, with such demand, more complex optical systems are required; thus, the network infrastructure is becoming more crowded. It is vital to economize on the available resources and infrastructure to ensure the needs of all interested business, governmental or end-user sides. Therefore, the present research focuses on the development of a unified hybrid optical system. The developed hybrid optical transmission system adds additional protection to the channels, allows for the unification of standard optical data transmission channels, optical sensors and spectrally hidden data transmission channel systems, and increases the efficiency of the optical components used. [ABSTRACT FROM AUTHOR]

The article investigates dependence of EDFA performance on its operating conditions. First of all, the impact of changes in channel spacing on the quality of the amplifier signal and on the desired EDFA configuration is observed – three different values of channel spacing are considered – 37.5 GHz, 50 GHz and 100 GHz. Afterwards, the impact of EDFA positioning on the quality of the amplified signal and the desired configuration is assessed. Three different EDFA positioning scenarios are considered – when the EDFA is used as a power booster, as an in-line amplifier and as a preamplifier. In all cases, such configuration of the EDFA is found that can ensure bit-error ratio (BER) values below 1·10−9 in all channels of the system. To assess the performance of the amplifiers, power penalty values are obtained in respect to identical transmission systems but without amplification. [ABSTRACT FROM AUTHOR]

The paper presents experimental study of the major erbium-doped fibre amplifier (EDFA) features such as gain at low signal and gain saturation by an application of different erbium-doped optical fibres (EDFs). The main objective of the research is to estimate how the performance of EDFA varies depending on the length of doped fibre, pumping configuration scheme, as well as excitation source power. It is shown that a high gain coefficient of 16–20 dB can be practically achieved. [ABSTRACT FROM AUTHOR]

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Due to ever increasing channel density in WDM systems the nonlinear optical effects in fibers become a limiting factor for the high-speed data transmission, which necessitates determination of such important characteristic as the coefficient of optical nonlinearity. To measure it, two methods are proposed: continuous wave self-phase modulation (CW-SPM) and pulse phase self-modulation (P-SPM). The research work has been carried out both in the form of calculations and experimentally, taking as wavelength the central one from the third optical transparency window, λ = 1550 nm. Based on the OptSim 5.2 simulations and experimental results, the sought-for nonlinear coefficients have been calculated. In the paper, comparative analysis and estimation of the results are performed for two different optical fibers. [ABSTRACT FROM AUTHOR]