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Information Capacity of Nonlinear Fiber-Optical Systems: Fundamental Limits and OCDMA Performance
Published in Paul R. Prucnal, Optical Code Division Multiple Access, 2018
Note that the cross-phase modulation [2], which severely limits the performance of advanced wavelength-division multiplexing systems [8] (WDM), does not affect the fundamental limit to the information capacity. The reason for this seemingly contradictory behavior is that in a WDM system the “receiver,” tuned to a particular WDM channel, has no information on the signals at the other channels. Therefore, even in the absence of the “genuine” noise, the nonlinear interaction between different channels, leading to a change in the signal in any given channel, will be an effective noise source, thus limiting the communication rate. This limit however is not fundamental, and can be overcome—for a system with “lumped” amplification by using a detector that probes all information channels, or—in case of distributed (such as Raman) amplification—by phase conjugation in the midpoint of the fiber link.
a system of four coupled, nonlinear Schrödinger equations with the effect of a coupling coefficient
Published in Kuppuswamy Porsezian, Ramanathan Ganapathy, Odyssey of Light in Nonlinear Optical Fibers, 2017
H. Tagwo, S. Abdoulkary, A. Mohamadou, C.G. Latchio Tiofack, T.C. Kofane
As regards applications, MI provides a natural means of generating ultra-short pulses at ultrahigh repetition rates and is thus potentially useful for the development of high speed optical communication systems in the future; hence it has been exploited a great deal in many theoretical and experimental studies for the realization of laser sources adapted to ultrahigh bit-rate optical transmissions [25, 26]. The MI phenomenon is accompanied by sideband evolution at a frequency separation from the carrier which is proportional to the square root of the optical pump power [27]. This represents the simplest case of MI in an anomalous dispersion medium with a simple Kerr nonlin-earity. When two or more optical waves copropagate through a birefringent optical fiber, they interact with each other through the fiber nonlinearity in such a way that the effective refractive index of a wave depends not only on the intensity of that wave but also on the intensity of other copropagating waves, a phenomenon known as cross-phase modulation (XPM) [1–3,5].
Active Optical Waveguides
Published in María L. Calvo, Vasudevan Lakshminarayanan, Optical Waveguides, 2018
Perhaps the most studied application of gain nonlinearities in active optical waveguides is in wavelength converters. The principles of cross-gain and cross-phase modulation as well as four-wave mixing have been exploited. A use of a waveguide integrated Mach–Zehnder interferometer with semiconductor amplifiers in each arm, schematically sketched in Figure 4.4, demonstrated wavelength conversion at up to 40 Gb/s. Only one input (Input 1 in Figure 4.4) was used in this case.
Advanced flexible wavelength routing based on Bragg trans-reflectance in 1550 nm VCSEL
Published in Journal of Modern Optics, 2020
G. M. Isoe, H. C. Cherutoi, D. W. Waswa, T. B. Gibbon
Wavelength conversion is a viable approach to wavelength routing and assignment in densely packed optical fibre links. Several wavelength conversion techniques have already been reported [6,7]. The choice of preferred wavelength conversion technique to use in is mainly dictated by some key requirements such as low power consumption, easy implementation and operation, high dynamic range as well as transparency to signal modulation formats [6]. Optical wavelength conversion techniques are among the fastest wavelength conversion technologies known today. Optical wavelength conversion includes techniques such as cross-phase modulation, cross-gain modulation (XGM), four-wave mixing (FWM) based on semiconductor optical amplifiers as well as nonlinear optical gating based on fibre loops [8–13]. However, each optical wavelength conversion technology has its attractive feature as well as its limitation. For instance, wavelength converters based on FWM technologies have the ability to support all modulation formats contrary to other types which are only limited to intensity modulation. However, the main drawback of FWM wavelength converters is the dependency of the output wavelength on both the pump and signal wavelengths, so the pump must be tuneable even with fixed output wavelengths.
Dynamic O-band to C-band wideband wavelength converter for integrated VCSEL-based optical interconnects
Published in Journal of Modern Optics, 2019
G. M. Isoe, D. K. Boiyo, T. B. Gibbon
Commonly used wavelength conversion technologies such as the use of opto-electronic converters are simple to implement, have low optical power requirements and potentially large input power dynamic range and are polarization insensitive. However, opto-electronic converters only operate up to 2.5 Gbps. For wavelength conversion in current and future high-speed optical network operating at data rates of 10 Gbps and possibly over 100 Gbps in future, power consumption and bandwidth limitation of opto-electronic converters may be the main limiting factor. Therefore all-optical conversion technologies will be a viable approach for future high-speed optical networks (2). Optical wavelength conversion techniques are among the fastest wavelength conversion technologies known today. Optical wavelength conversion includes techniques such as cross-phase modulation, cross-gain modulation (XGM), four-wave mixing (FWM) based on semiconductor optical amplifiers as well as nonlinear optical gating based on fibre loops (5–12), super continuum (13), cross-phase modulation (14, 15) and fast nonlinear polarization switching (16). For instance, wavelength converters based on FWM technologies have the ability to support all modulation formats contrary to other types which are only limited to intensity modulation. Moreover, FWM wavelength converters are ideal for ultrafast signal applications such as at bitrates above 100 Gbps. However, the main drawback of FWM wavelength converters is the dependency of the output wavelength on both the pump and signal wavelengths, so the pump must be tuneable even with fixed output wavelengths. Consequently, two pumps are needed to ensure polarization insensitive operation (17). Cross-grain modulated (XGM) converter technique on the other hand is easy to ensemble, power efficient and is polarization insensitive due to SOA gain polarization independence. However, the main short coming of this technique is that the converted signal is inverted relative to the input signal. XGM wavelength converters are also associated with relatively large frequency chirps (18). Moreover, the SOA add spontaneous emission noise to the converted signal therefore degrading the quality of signal (QoS). All-optical wavelength conversion techniques offer key building block for design and implementation of optical burst switch (OBS) routers, which are preferred in high-speed optical networks with dynamic ultrafast data patterns. Research studies on optical packet switching have already been presented (19–21). Photonic packets switches offer high switching speed, supports high data rates, format transparency and flexibility of telecommunication networks. Advances in laser technologies have also created new architectural options for wavelength converting switches and appear to stand as a promising consideration for practical optical switching systems. nt resolution reduce node jam probability, increase optical transparency and enable dynamic network wavelength assignment as well as allocation capability. Some all-optical wavelength schemes have already been demonstrated with many promising results.