Coherent high-speed optical systems have played a very significant role in the world of data transmission in the last 15 years, and transmission speeds from 1.2 Tb/s to 1.6 Tb/s per lambda are expected to enter the market very soon. Historically, legacy high-speed 10 Gb/s data transmission systems have used the simplest On-Off Keying (OOK) modulation scheme. Since data transmission systems have been gradually moving to coherent transmissions with advanced modulation schemes, the coexistence of slower signals using OOK modulation can have a significant impact on coherent data signals via the nonlinear effect of Cross-Phase Modulation (CPM). In this paper, we evaluate the Bit Error Rate (BER) and Optical Signal-to-Noise Ratio (OSNR) for legacy 10 Gb/s data signals transmitted together with high-speed coherent 200 Gb/s data signals for fiber distances ranging from 100 km to 800 km. This scenario is rather suitable for National Research and Educational Network (NREN) operators, where slow OOK and high-speed coherent data signals are transmitted on the predefined International Telecommunication Union (ITU) channel spacing, usually 100 GHz.
In the period following the COVID-19 outbreak, there continues to be a demand for high-speed data services and sufficient bandwidth. From a transport network perspective, a coherent system transmits data independent of the specific transmission wavelengths . However, it is desirable to address the transmission of slow signals (e.g., OOK) in the same fiber and their interaction between transmissions. Here, we assess the effect of a slow signal with a low modulation rate in a DWDM network on high-speed (super channel) 800G transmission. To evaluate the effect on high-speed transmission, the Q factor and ESNR parameters provided by the Ciena transmission system were analyzed. For the test setup and the combination of the coherent 800G signal with the standard DFB transceiver signal and 100 GHz spacing. The 800G signal required 112 GHz bandwidth for its transmission. For a path length of 200 km and for modulation rates of the OOK signal ranging from 100 Mbit to 4 Gbit, we found no significant effect on the evaluated parameters of the Q factor and ESNR of the transmitted 800 G signal. The more significant effect on the 800G signal is, the mutual power level of neighboring channels with different modulation types. To limit the mutual influence of adjacent signals, these signals must also be balanced according to their maximum (peak) power level in the transmitted spectrum.
Passive optical networks play an important role in access networks and in current 5G networks. Passive optical network (PON) recommendations are published for two sectors by the Institute of Electrical and Electronics Engineers (IEEE) and the International Telecommunication Union (ITU), covering transmission speeds from 1 to 100 Gbit with wavelength division multiplex (WDM). The recommendations of the ITU define different encapsulation methods for the Ethernet frame, and meeting these recommendations necessitates new tools for control and data transmission. We present a downstream frame bandwidth field analysis for the simple topology of an XG-PON with 2 ONUs. The main purpose is to prove that the current access networks do not rely only on Ethernet frame transmission.
In this paper we present the design of a layered technical textile blocks for measuring temperature and strain using FBG gratings. In addition to research into individual layers of technical textiles, we also deal with joining methods to ensure sufficient strength while maintaining the flexibility of the created textile block. The textile with dimensions of 1x1 meter is designed for use in critical infrastructure security, such as a protection of secured area. A unique, robust connector using GRIN lenses was designed to connect the individual blocks. This special connector has dimensions 30x10x4.5mm and insertion loss of about 5dB.
Since optical fibre is a standard medium for all current and new networks, these optical networks offer possibility for connecting new applications over long distances almost to anywhere. However with increasing number of applications, the large number of dedicated fibres will be necessary. This constitution is quite unpractical in terms of costs, however since wavelength division multiplexing enables transmission of multiple different signals over one fibre it is more than suitable to use this technology for cost reduction and network efficiency increase. Wavelength division multiplexing technology is common in data networks where parameters of all signals may be optimized (especially maximum optical power launched into the fibre) for simultaneous transmission. In case of non-data applications the situation is more difficult because each application is connected by different type of signal and with its own requirements for transmission parameters. Hence it is necessary to evaluate possible interactions before field deployment. In this paper we deal with possible interaction of a coherent 100 Gb/s dual polarisation QPSK data signal with new applications like accurate time and stable frequency transmission and high-power pulse signal used for distributed sensing. In laboratory setup we performed a measurement with a standard G.652D single mode optical fibre and also with G.655 fibre which can also be found in some networks and may be source of more nonlinear interactions. All signals were transmitted in a grid with 100GHz spacing according to ITU standard. Results confirmed our assumptions that 100GHz spacing is not large enough and also that G.655 optical fibre is prone to more non-linear interactions.
Phase-sensitive optical time-domain reectometry (Φ-OTDR) seems to be the most appropriate solution for acoustic vibration along standard optical fiber detection. In general the sensing system measures phase changes of the received Rayleigh back-scattered signal in the fiber. Since the back-scattered signal intensity is decreased about tens of decibels in comparison to the forward propagating pulse power level, the received signal power level is very low. That is why the main limiting parameter of the system is the power level of the back-scattered signal, which limits maximum achievable distance. For long reach sensing it is necessary to create high power optical pulses with short time-duration. Direct pulse amplification by erbium doped fiber amplifier (EDFA) is an issue because of the pulses low repetition rate. We have designed and verified a simple method using a holding beam for amplifying of pulses with low repetition rate by standard telecommunication EDFA booster instead of deployment of an expensive optical shutter. A second CW laser with a different wavelength for EDFA stabilization is used in our setup. Because a pulse losses its energy during propagation in the fiber and with longer distances by 1st order Raman amplifier (RA). In telecommunications this amplifier is used to compensate for fiber losses. The second setup uses remote amplification by remotely pumped erbium doped fiber (EDF) placed after a few tens of kilometers of sensing fiber. A pump laser is placed in the transmitter part of the system from where EDF is pumped. In this paper, we present an overview of few techniques for Φ-ODTR signals amplification and their verification by measurement.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.