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The article contains information about the monographic studies, which investigate the biography of the outstanding singer and film actress of the first half of the 20th century - Maria Cebotari. This subject constituted a field of research both for the authors of monographs contemporary to the prima donna and those of our days - representatives of different countries and specializations. In this context, the most important of their works (books, brochures, articles), which have scientific value are described and analyzed. Although M. Cebotari`s biography is widely presented, it can be supplemented with new investigations, thanks to the immense artistic heritage of the diva

The article contains information about the achievements of M. Cebotari in the interpretation of the vocal-symphonic works of the composers of the Viennese classical era: J. Haydn, W.A. Mozart and L. van Beethoven Unique, little-known materials about the singer’s participation in numerous concerts in Vienna and other cities of Austria, where their compositions were performed are collected and analyzed. Of great interest for the study are the critical materials published in the newspapers of that time, which are the main source of information on the subject. Additionally, the dates, places and participants of the concerts are indicated.

We transmit 143x32.6 GBd 8D-QPSK signal over 15,050 km with EDFAs consuming 29 mW of 980 nm-pump power. We experimentally achieve record optical power efficiency from 6.5 to 1.24 Tb/s/W with the corresponding optimum spectral efficiency from 2.4 to 2.0 b/s/Hz for transmission distances ranging from 6,020 to 15,050 km respectively. These results are enabled by: precisely tuned information spectral efficiency and EDFA output power based on our power efficiency model to maximize optical power efficiency; the use of coded modulation format with <1.6 dB gap to Shannon limit and variable overhead FEC; the use of ultra-low loss fiber; more power efficient gain equalization with a single gain flattening filter per two EDFAs; and low back-to-back implementation penalty. We also confirmed the validity of our power efficiency model comparing the designed and measured OSNR evolution, achieved optical power efficiency and the corresponding spectral efficiency. [ABSTRACT FROM AUTHOR]

This article will discuss the collaboratively formed cross-industry open cables concept for characterizing optical performance of undersea cables with the intent of assessing and understanding their capacity potential. The article proposes definitions of two critical nonlinear and linear performance metrics for open cables: GSNR (Gaussian or generalized signal to noise ratio) and SNRASE (Signal to noise ratio amplified spontaneous emission), including effects such as GAWBS (guided acoustic wave Brillouin scattering) and signal droop. Measurement methodologies for these metrics are proposed, with considerations for limitations and impact of the test conditions and characteristics of the transponders used. Expanded definitions are offered to enable variable symbol rate transponders to be used for measurement, with considerations for scaling of SNR values. Considerations for using these metrics for capacity assessment and applying these techniques to concatenated multi-segment systems are introduced. Recommendations on key parameters for system specification, system characterization, and proposals for SNR-based performance budgeting tables are also discussed as foundational elements to enabling accurate estimation of the capacity potential of a subsea open cable. [ABSTRACT FROM AUTHOR]

We study and compare performance of probabilistically shaped (PS)-64QAM formats (with spectral efficiency ranging from 3.6 to 8.6 b/s/Hz) and coded modulation (CM)-64/16APSK formats with PS or geometric shaping (GS) or hybrid shaping (HS) with spectral efficiency ranging from 4.8 to 8.8 b/s/Hz. We show that a well-designed CM-64/16APSK format could exceed the performance of PS-64QAM formats by a small margin both in back-to-back and transmission. This was verified for transmission distances from 4,435 to 22,176 km using laboratory hardware and our implemented FEC. We show similar nonlinearity compensation (NLC) benefit for both PS and CM formats using 3-stage NLC schemes. The NLC benefit increases from 1.2 to 1.6 dB as the transmission distance increases from 4,435 to 9,504 km and then nearly saturates at ∼1.6 dB after ∼10,000 km. Furthermore, we experimentally demonstrate 71.6 Tb/s (7.36 b/s/Hz) using a CM-64/16APSK format and 70.3 Tb/s (7.22 b/s/Hz) with a PS-64QAM format over 6,970 km using C+L band EDFA testbed. [ABSTRACT FROM AUTHOR]

We consider both physical and economic aspects of submarine transmission to identify optimal designs of submarine space division multiplexed (SDM) systems. We focus on single mode-based SDM systems as the first practical step for implementation of high capacity, low cost-per-unit-capacity systems based on SDM principles. We review power efficiency models in EDFA-based long-haul systems and show existence of optimum SNR. We demonstrate relationship between the power efficiency and cost-per-unit-capacity optimizations for submarine links. We also describe a detailed model that combines physical and economic aspects of the submarine links. The model uses “least amount of technological change” approach based on the existing components and simple scaling rules for repeater and cable designs. The model results suggest that 32-fiber SDM systems are a practical spot for near-future systems close to cost-per-unit-capacity limit of the wet-plant. Further increase of the number of fibers in a cable has diminishing returns for current technologies and cost structure. We also discuss requirements for transponders in terms of spectral efficiency and nonlinearity compensation. [ABSTRACT FROM AUTHOR]

We discuss space division multiplexing as a means of increasing link capacity for power limited transmission in undersea communication. Theoretical study of erbium-doped fiber amplifiers-based space division multiplexing (SDM) transmission shows the existence of optimal values of spectral efficiency, signal-to-noise ratio, and span length that maximize power efficiency. We experimentally confirm the existence of an optimal spectral efficiency and demonstrate power efficient SDM transmission using 12-core multicore fiber. Modulation format, amplifier, and link design are discussed in connection to SDM power efficient transmission. [ABSTRACT FROM AUTHOR]

We demonstrate 70.46 Tb/s transmission over 7,600 km and 71.65 Tb/s transmission over 6,970 km with C+L band EDFAs using a multidimensional coded modulation format with hybrid probabilistic and geometric constellation shaping. The proposed format (4D-PS-9/12-56APSK) is designed to approach Shannon limit and to improve the performance of nonlinearity compensation over conventional and probabilistically shaped 2-D formats. The receiver DSP uses multistage nonlinearity compensation that includes fast least-mean-square equalizer and generalized filter in addition to digital back propagation. The adaptive linear filters are aided by coded modulation decisions.We study the contribution of each algorithm and show an average total nonlinearity compensation benefit of 1.4 dBQ at the designed amplifier power. [ABSTRACT FROM AUTHOR]

We use multicore fiber to demonstrate power efficient, high capacity ultralong-haul spatial division multiplexing (SDM) transmission. Feasibility of 105.1 Tb/s transmission over 14,350 km in a 12-core fiber is shown using a power efficient modulation format and an optimized optical system design. Pump power equivalent to a single 800 mW laser is used to provide amplification for all 12 SDM paths. [ABSTRACT FROM PUBLISHER]

The capacity of optical communication systems can be continuously scaled by utilizing spatial division multiplexing (SDM) technology. However, this scaling has significant impact on the required optical and electrical power as the number of EDFAs increase. This constraint is crucial in long-haul undersea optical systems where electrical power for the entire system is fed from the landing points. Successful implementation of SDM in undersea systems will require both signal modulation and amplification technologies with high power efficiency. In this work, we use 8-D coded modulation and simple EDFA design to demonstrate 100 Gb/s transmission over 9750 km with record high power efficiency as defined by the ratio of capacity-distance product to the total amplifier output power. [ABSTRACT FROM PUBLISHER]

We demonstrate the existence of an optimal spectral efficiency that maximizes the power efficiency and/or capacity of a power limited erbium-doped fiber amplifier (EDFA)-based space division multiplexing transmission system. Optimal spectral efficiency observed experimentally is in good agreement with a theoretical estimate. [ABSTRACT FROM PUBLISHER]

We transmit 106 × 200 Gb/s channels over 10 290 km at 6.0 b/s/Hz enabled by Nyquist spectral shaping and digital back propagation (DBP). 53 × 400 Gb/s channels are also transmitted over 9200 km detecting two 200 Gb/s wavelengths simultaneously using a wideband receiver. DBP benefit versus channel pre-emphasis, average launch power per channel, and transmission distance are experimentally investigated. We find the DBP benefit scales monotonically with channel power and transmission distance. Measurement results match well with theory. [ABSTRACT FROM PUBLISHER]

We demonstrate that channel spacing can be reduced to values smaller than the Nyquist channel spacing over transoceanic distance. Modulation memory induced by constrained transmitter bandwidth together with multisymbol detection can reduce intersymbol interference for systems with sub-Nyquist channel spacing. We transmit 198 × 100 G bandwidth constrained polarization-division-multiplexed return-to-zero quaternary phase shift keying channels with 400% spectral efficiency over 6860 km using 52 km spans of 150 μ m2 fiber and simple single-stage erbium-doped fiber amplifiers without any Raman amplification. We also show that 100 G coherent nonlinear performance scales differently with distance on uncompensated dispersion maps compared with direct detection transmission. [ABSTRACT FROM PUBLISHER]

Polarization-related effects are the major source of performance fluctuations in long-haul systems. Understanding the system implications of polarization-dependent loss, polarization mode dispersion, linear and nonlinear channel crosstalk, polarization-dependent gain, and polarization hole burning is important for a successful system design and operation. In this paper, the polarization and nonlinearity-driven performance fluctuations in 10-Gb/s wavelength-division multiplexing submarine transmission systems, including repeatered and unrepeatered systems, are analyzed. The proposed phenomenological model of performance fluctuations shows good agreement with data accumulated over a long period on deployed repeatered systems. Furthermore, the case of 40-Gb/s transmission is briefly discussed [ABSTRACT FROM PUBLISHER]

This paper reviews technologies and techniques that have been used in deployed long-haul wavelength division multiplexing (WDM) systems and emerging technologies that could be used for the next generation of cost-reduced systems. The overview of current generation technologies starts with a discussion of modulation formats, focusing on the superior properties of the chirped return to zero on-off shift keying (CRZ-OOK) modulation format. The use of 10-Gb/s CRZ-OOK modulation format together with advanced fiber types, more powerful forward error correction (FEC), and broadband erbium-doped fiber amplifiers resulted in the deployment of dense WDM systems with capacities per fiber in terabits per second range and trans-Pacific reach. Demand for the systems with large design capacity led to further development of broadband optical amplifiers. Laboratory demonstrations successfully expanded transmission into the full C-band and later in the C and L transmission bands. The current market conditions dictate the need for reducing the first cost of an installed system rather than reaching record capacity per fiber. Reducing first cost can be achieved by reducing the amount of optical amplifiers in the cable by utilizing an excess performance margin provided by available RZ-OOK technology. Further improvements would be possible if more powerful FEC and modulation formats with better receiver sensitivity are used. For example, the RZ differential phase-shift keying (RZ-DPSK) modulation format with 3-dB better receiver sensitivity and better nonlinear tolerance to large amounts of accumulated dispersion is a very promising technology. This paper will review long-haul transmission results using RZ-DPSK and will compare the transmission properties of RZ-DPSK signals versus RZ-OOK signals. Due to superior receiver sensitivity, the RZ-DPSK modulation format can be an enabling technology for 40-Gb/s per channel transoceanic transmission [ABSTRACT FROM PUBLISHER]

This paper investigated the impact of receiver dispersion slope compensation for 40-Gb/s transoceanic transmission over conventional nonzero dispersion shifted fibers. Various differential phase-shift keying (DPSK) modulation formats were experimentally compared at 42.8 Gb/s [to account for forwarded error correction (FEC) overhead] with dispersion slope compensators at the receiver. These transmission measurements were performed in a circulating loop over a transatlantic distance of 6250 km using a variety of channel spacings, relative polarizations, and synchronous modulation techniques. All formats benefited from receiver dispersion slope compensation. For orthogonally polarized channels on 133-GHz spacing, the return-to-zero DPSK (RZ-DPSK) format performed the best; all channels (18 × 40 Gb/s) propagated with > 13.5-dB Q-factor and with > 4-dB FEC margin. Whereas for copolarized channels on 100-GHz spacing, carrier-suppressed return-to-zero (CSRZ)-DPSK performed the best; all channels (25 × 40 Gb/s) propagated with > 3-dB FEC margin. Moreover, it was shown that parallel launch only suffered a penalty of ∼ 0.2 and ∼ 0.5 dB relative to the orthogonal launch for 133and 100-GHz channel spacing, respectively. Finally, it was demonstrated that copolarized 40 Gb/s RZ-DPSK worked as well as 10 Gb/s RZ-ON-OFF keying (RZ-OOK) for the same spectral efficiency (30%) over the 6250 km of conventional nonzero dispersion shifted fibers (NZ-DSF) originally designed for 10 Gb/s transmission. [ABSTRACT FROM PUBLISHER]

This work presents the first field trial using the return-to-zero differential-phase-shift-keying (RZ-DPSK) modulation format. A 96×10-Gb/s RZ-DPSK field trial was conducted over a 13 100-km optical undersea path by double passing the installed 6550-km underwater link which was deployed with non-slope-matched submarine fibers. All channels performed with more than a 3-dB forward-error correction margin, including channels that accumulated over ±13 000ps/nm of dispersion. It is also shown that the RZ-DPSK format has similar residual dispersion and channel power tolerance for both slope-matched and non-slope-matched fibers. Furthermore, it is demonstrated that the chirped RZ-DPSK format could further improve system performance by 1-2 dB. [ABSTRACT FROM PUBLISHER]

Product accumulate (PA) codes were proposed as a class of high-rate low-complexity, capacity-approaching codes on additive white Gaussian noise (AWGN) channels. In this paper, we investigate the performance of the PA codes on intensity modulated optical fiber channels where the amplified spontaneous emission (ASE) noise dominates all other noise sources. We consider binary on-off keying (OOK) modulation and iterative soft-decision message-passing decoding for the PA codes. Three channel models for the ASE noise dominated channel are investigated: asymmetric chi-square, asymmetric Gaussian, and symmetric Gaussian channels (i.e., AWGN). At low signal-to-noise ratios (SNRs), due to the lack of tight bounds, code performance is evaluated using simulations of typical PA coding schemes. For high SNRs that are beyond simulation capabilities, we derive the pairwise error probability of the three channels and explore an average upper bound on the bit-error rate over the ensemble of PA codes. We show that AWGN channels, although fundamentally different from chi-square channels, can serve as a reference to approximate the performance of high-rate PA codes. [ABSTRACT FROM PUBLISHER]

We present an experimental investigation of 40 Gb/s transmission technology aimed at an aggregate capacity exceeding 1 Tb/s over multithousand kilometer transmission distances. These studies have been performed using a variety of dispersion management and modulation techniques. The transmission distances investigated range from a minimum of 2000 km, which is considered a regional undersea cable distance, up to a transatlantic distance of 6200 km. Our regional distance experiments were performed using both slope-matched and conventional dispersion maps where the accumulated dispersion becomes large for the edge channels. Dispersion map studies showed that slope-matched fiber performs better than nonslope-matched fiber (NZDSF) beyond 2000 km due to its larger effective area and lower accumulated dispersion slope. The demonstration of 38×40 Gb/s over 6200 km was the first transoceanic length experiment using 40 Gb/s DWDM channels. This was achieved with a relatively simple amplifier chain that uses only C-band EDFAs. Modulation format studies showed that RZ performs better over transoceanic distance, carrier-suppressed RZ performs better with nonslope-matched fiber at a distance of 2055 km, and prefiltered carrier-suppressed RZ is more suited for higher spectral efficiency. Experimental techniques for high bit-rate experiments are presented. [ABSTRACT FROM PUBLISHER]

Nonlinear interaction between signal channels may result in significant performance degradation in transoceanic dense wavelength-division-multiplexing (WDM) transmission systems operated at high bit rates. In this paper, we report that the nonlinear crosstalk for systems with high spectral efficiency can be suppressed if WDM channels are launched with orthogonal relative states of polarization. It is shown that for adjacent channels (that experience the strongest nonlinear interaction) the launched relative state of polarization is maintained over the large distance of low polarization-mode dispersion fiber typically used in undersea systems. Numerical studies, as well as experimental results, are presented for standard and dispersion slope-matched dispersion maps [ABSTRACT FROM PUBLISHER]

The rapid growth of long-haul wavelength-division multiplexing (WDM) fiber-optic telecommunications challenges lightwave system designers to increase the transmission capacity per fiber pair, while reducing the time to market. This makes it essential to have fast and accurate computer modeling tools to aid the systems design. There is a natural engineering tradeoff between simulation speed and accuracy; fast approximations tend to be inaccurate, while the exact treatment of the physical processes affecting transmission are nearly impossible to capture in a time-efficient algorithm. The proof of a successful tool development lies in the comparison of simulation results to transmission system measurements. In this paper, we discuss a new simulation technique based on careful evaluation of the key physical effects that produce system impairments. We show that this new approach can produce fast and accurate simulations of long-haul WDM transmission systems [ABSTRACT FROM PUBLISHER]

Dispersion compensation placed at the end of a nonlinear system affects both signal variance and pulse distortion. This letter shows experimentally and theoretically that optimum performance for a wavelength-division-multiplexed test bed of 4870 km is achieved by selecting dispersion compensation to minimize pulse distortion rather than signal variance [ABSTRACT FROM PUBLISHER]

The first transoceanic transmission experiment using optical differential quadrature phase-shift keying (DQPSK) is presented. The long-haul transmission capabilities of RZ-DQPSK in a 64-channel WDM system have been demonstrated by transmitting 12.5 Gbit/s RZ-DQPSK [ABSTRACT FROM AUTHOR]