Jurgis Porins

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.

Noise Figure Analysis of EDFA with different pumping configurations in 40 Gbit/s 8 channel DWDM transmission system

In this research we investigated the performance of in-line Erbium Doped Fiber Amplifier (EDFA) in 40 Gbit/s 8 channels wavelength division multiplexing (WDM) transmission system with NRZ-OOK modulation format and 100 GHz channel spacing. Different EDFA configurations: co-propagation (980nm) and counter propagation (1480nm) were used in order to find an optimal settings with minimal noise factor indicators. Results show that in general the pumping wavelength of 980nm gives a stable noise factor values within 4 - 4.5 dB both for 10m and 30m long fibers. With the increase of pump power and fiber length, counter-propagation at pumping wavelength of 1480nm provides noticeably high noise up to 9-15 dB.

Comparison of reliability of ADSS cables mounted on different voltage electric power lines

In this paper authors provide the results from the research about all-dielectric self-supporting optical cables reliability when these cables are mounted on the rests of high voltage electrical power lines. Comparison of reliability parameters is given between optical cable lines mounted on the power lines up to 110kV and 330kV. Additionally measurement results of fiber polarization mode dispersion and maximum tensile load are given for different all-dielectric self-supporting cables.

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.

Minimization of FWM effect in nonlinear optical fiber using variable channel spacing technique

Optical Fiber Communication widely implements Dense Wave Division Multiplexing (DWDM) technique in order to accommodate large number of channels within a limited bandwidth. But, this technology suffers a serious degradation in signal quality due to inter-channel interference. Optical Kerr Effect, in addition to this, worsens the situation. This paper deals with minimization of Four Wave Mixing (FWM) impact, one of the Optical Kerr effects, by using variable channel spacing instead of conventional fixed channel spacing technique. FWM effect generates spurious components at multiple frequencies, whose effective amplitude can be reduced using different channel spacing. Bit Error Rate (BER) observed for different length of fiber has been analyzed with an aim to estimate the difference between variable channel spacing algorithms. Obtained results have shown that BER of 10–11 can be reached with 153.7 km long fiber for fixed channel spacing while the usage of variable channel spacing method keeps the same BER level with 160.5 km long fiber.

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.

Fiber Bragg Grating Technology for New Generation Optical Access Systems

Thanks to achievements in photonics technologies optical networks have gained a notably increase in capacity per single fiber during the last decade [1]. Demand for greater transmission speed has been increasing exponentially because of the impulsive spread of Internet services (see Fig. 1) [2]. At the same time, the radical improvement of the capability of digital technologies has made feasible expanding multimedia services [1]. Therefore bandwidth intensive applications and exponential Internet traffic growth are continuing to drive the further penetration of optical fiber into the optical access systems [2].

Evaluation of SPM-induced optical signal distortions in ultra-dense mixed-WDM system

The authors have investigated the impact of self-phase modulation (SPM) induced distortions to optical signal transmission over proposed configuration of spectrally efficient wavelength division multiplexed (WDM) fiber-optic transmission system (FOTS). In chosen model of ultra-dense mixed-WDM system optical signals are transmitted with two different per channel bitrates (i.e., 10 and 40 Gbit/s) and three different optical signal modulation formats are used for the encoding of transmitted data (i.e., non-return to zero encoded on-off keying or NRZ-OOK, orthogonal polarization shift keying or 2-POLSK and NRZ encoded differential phase shift keying or NRZ-DPSK). In addition, “non ITU-T” defined minimum and equal frequency intervals are used for the channels separation. This research revealed that 2-POLSK modulated signals are more susceptible to the impact of SPM in such ultra-dense mixed transmission mode than e.g., NRZ-DPSK signals.