Sergejs Olonkins

Hybrid optical amplifiers for flexible development in long reach optical access system

In this paper the authors have investigated the performance improvement in long reach optical access system with hybrid optical amplifiers. The apparent options of optical amplification in wavelength division multiplexing systems include the distributed Raman amplifiers, erbium doped fiber amplifiers, and semiconductor optical amplifiers. In our case distributed Raman amplifier is located at the mid-span reach extender which allows for remote amplification in passive network nodes by distributing a Raman pump together with the data signals. In the case of only distributed Raman amplifier in long reach optical access system wavelength division multiplexing exploitation is inefficient. Combining the advantages of different amplifiers allows fast gain dynamics, simultaneous large bandwidth amplification, and the ability to provide gain at any wavelength. Degradation of optical signal quality is evaluated in 10 Gbit/s long reach wavelength division multiplexing optical access system with hybrid distributed Raman-erbium doped fiber amplifier and distributed Raman-semiconductor optical amplifier.

Realization of dense bidirectional spectrum sliced WDM-PON access system

The present paper proposes high speed dense 8-channel bidirectional WDM-PON access system where spectrally-uniform ASE source is shared among multiple users for realization of downstream transmission. Upstream transmission is realized by using conventional laser based solution. Proposed system is based on ITU-T DWDM grid and operating at 10 Gbit/s per channel symmetrically on both directions. It is demonstrated that implemented spectrum slicing technology is capable to provide downstream data transmission over 20 km SMF fiber span with BER<;10-12 by using additional fiber Bragg grating chromatic dispersion compensation module and excess intensity noise reduction by additional semiconductor optical amplifier.

Binary PolSK to OOK modulation format conversion in single-pump FOPA for optical access networks

The interest of implementation of advanced modulation formats in metro and access networks has experienced a steady increase under the influence of exponentially increasing data amount from multimedia services like videoconferencing, high definition television, video on demand, interactive games and others. The transition period to advanced modulation formats requires a solution for efficient all-optical modulation format conversion to avoid replacement of the existing end-user hardware with the more expensive and complex devices capable of processing of advanced modulation formats. In this paper the authors have investigated the opportunity of all-optical modulation format conversion from binary polarization shift keying to intensity on-off keying in optical metro and access network using a single-pump fiber optical parametric amplifier. This preamplifier ensures up to 30 dB of gain and provides efficient modulation format conversion in the access network. Such additional functionality of single-pump parametric amplifiers in optical access networks has not been demonstrated so far.

Cost effective WDM-AON with multicarrier source based on dual-pump FOPA

The aim of this paper is to demonstrate the ability of a fiber optical parametric amplifier to increase the number of carriers two times in a 32 channel wavelength-division-multiplexed active optical network. The parametric amplifier is placed at the receiver section. The 32 carriers are obtained by using 16 initial carriers, which while processing through the high non-linearity fiber, initiated the generation of 16 phase-conjugated spectral components that afterwards were used as transport for the informative signal. The provided solution has ensured even distribution of all 32 channels with channel spacing of 100 GHz with power non-uniformity just below 2dB among all 32 carriers. It is demonstrated that the provided solution with the introduced cost-effective seeded four-wave-mixing based multicarrier light source is capable to provide downstream data transmission over 20 km long standard single-mode fiber span simultaneously ensuring bit-error-ratio values below the 10-12 threshold for all of the 32 channels.

Investigation of in-line EDFA performance dependence on channel spacing in WDM transmission systems

The aim of this paper is to estimate the impact of changing channel spacing in a wavelength division multiplexed (WDM) transmission system on the performance of the in-line erbium doped fiber amplifier (EDFA). The performance of the EDFA was investigated in a 16 channel 9.953 Gbit/s WDM transmission system with non-return-to-zero encoding technique, intensity on-off keying modulation format (NRZ-OOK) and three different values of channel spacing (37.5 GHz, 50 GHz and 100 GHz). The single-pump EDFA solution with co-propagating pumping radiation and 12 m long erbium doped fiber was used. To estimate the impact of changes of channel spacing on the performance of the in-line EDFA, the minimal pump power that is required to ensure a certain quality of the signal for each channel spacing was found. To assess the performance of the EDFA, the dependences of the maximal BER values among all the channels on the power of the detected signals for each channel spacing are compared to the same results obtained in a 16 channel WDM system with the corresponding channel spacing but without amplification. Power penalty values are evaluated at each channel spacing in respect to the solution without amplification.

Evaluation of Parametric and Hybrid Amplifier Applications in WDM Transmission Systems

Over the past two decades, a rapid expansion of the amount of information to be transferred has been observed. This tendency is explained by the rapid increase of Internet and other service users, as well as with the increasing availability of these services. This rapid growth in the amount of globally transmitted data is also associated with the expansion of the range of services offered, including such resource-consuming services as high-resolution video transmission, videoconferencing, and cloud computing, as well as with increasing popularity of such services. To satisfy this constantly increasing demand for higher network capacity, fiber optical transmission systems have been studied and applied with a growing intensity. Currently, optical transmission systems with wavelength-division multiplexing (WDM) have attracted much attention, as this technology allows using the available optical fiber resources more effectively than alternative technologies.

Demonstration of binary PolSK to OOK modulation format conversion using a single-pump fiber optical parametric amplifier

The main goal of this paper is to investigate the ability of a single-pump fiber optical parametric amplifier with linearly polarized pumping radiation to provide binary polarization shift keying to intensity on-off keying modulation format conversion in a single channel optical transmission system. The amplifier produced up to 14.8 dB of on-off gain, and it was demonstrated that such level of amplification is sufficient to provide modulation format conversion, while maintaining acceptable quality of the converted signal. It was found that due to fiber birefringence the original state of polarization needs to be recovered at the input of the amplifier, otherwise, drop in amplification and converted signal discrepancies will occur.

Investigation of Dual-Pump FOPA Performance in a 4-Channel 40 Gbps WDM Transmission System

Fiber-optical parametric amplifiers (FOPA) are positioned as the future leading technique for optical signal amplification. This type of amplifiers is highly appreciated due to their applications in all-optical signal processing. Signal amplification can be achieved using single-pump or dual-pump pumping schemes. Dual-pump FOPAs provide smoother gain over wider bandwidth than single-pump FOPAs, but it is harder to maintain high performance of dual-pump FOPAs due to the stimulated Raman scattering (SRS) induced energy transfer from one pump to another. In this paper the authors investigate the performance of a dual-pump FOPA under the influence of SRS in order to ensure higher gain using as low pump power as possible in a 4-channel 40 Gbps wavelength-division multiplexed transmission system. DOI: http://dx.doi.org/10.5755/j01.eie.23.6.19699

Investigation of EDFA positioning impact on the quality of the amplified signal in DWDM transmission systems

Due to the all-time growing demand for higher network capacity, during recent years a lot effort was made not only to build new high performance optical transmission systems, but also to improve the operation of already existing systems. Optical amplifiers are such type of network elements the operation of which can severely impact the performance of a whole system. Many factors can impact the performance of an optical amplifier, but the most significant of them is the power of the input signal, which can be varied by changing the position of an amplifier in the optical link. Erbium doped fiber amplifiers (EDFA) are the most commonly used type of amplifiers in modern optical transmission systems. This is why in this research the authors investigate the impact of EDFA positioning in a dense wavelength-division multiplexed transmission system (DWDM) on the quality of the amplified signal, aiming to improve the performance of EDFAs in existing WDM transmission systems. Three different scenarios were considered: when the EDFA was used as a power booster, as an in-line amplifier and as a preamplifier. In all three cases such EDFA configurations were obtained that could ensure the required quality of the signal by using as low pump power as possible.

Investigation of in-line distributed Raman amplifiers with co and counter-propagating pumping schemes

The main goal of this paper is to investigate and compare the performance of an in-line distributed Raman amplifiers in cases of co and counter propagating pumping radiation in respect to the propagation direction of the amplified signal. The performance analysis is based on the results obtained in a 16 channel 10 Gbps dense wavelength division multiplexed optical transmission system with 50 GHz channel spacing, non-return-to-zero intensity on-off keying modulation format, and an in-line DRA was introduced. The main requirement that was set by the authors was that the power of the pump should not exceed 1 watt. While configuring the in-line DRA wavelength of the pumping radiation and the positioning of the amplifier chosen for both co and counter-propagating pumping schemes.