Our proposed approach for increasing the transmission capacity is to reduce the channel spacing of a DWDM-direct system to the minimum while keeping the employed optical band-pass filter ...technologies. For the DWDM-direct system with 55 GHz FBG a satisfactory performance is achieved with a 50 GHz channel interval at the 10 Gbit/s data transmission speed leading to the increase of spectral efficiency for overall system from 0.18 bit/s/Hz to 0.2 bit/s/Hz.
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.
The upper transmission range of the wavelength division multiplexing passive optical network (WDM-PON) can be restricted by chromatic dispersion (CD). This paper contains the investigation of till ...16-channel WDM-PON system with efficient CD pre-compensation and post-compensation methods. It is shown that CD offset has a marginal role for guaranteed optical link downstream performance and maximum length of high-speed WDM-PON system. The results show that employment of extra 7 km long dispersion compensating fiber (DCF) placed in central office (pre-compensation configuration) enhances the WDM-PON network link length by 19.3% (from 57 km up to 68 km), but if extra 2 km long DCF fiber is used in remote terminal (post-compensation configuration) link length can be extended up to 5.3% (from 57 km to 60 km). It was found that usage of fiber Bragg grating (FBG) in central office (pre-compensation configuration) improves network reach up to 26.3% (from 57 km up to 72 km), but using this FBG for CD post-compensation in remote terminal network reach can be improved by 15.8% or 9 km in length - from 57 km to 66 km. Basis on the results authors recommend to use FBG as the best solution for CD compensation in pre-compensation configuration (before SMF line) in future high speed long-reach DWDM-PON systems.
Reach Improvement of Spectrum-Sliced Dense WDM-PON System Spolitis, S.; Bobrovs, V.; Ivanovs, G.
2012 Seventh International Conference on Broadband, Wireless Computing, Communication and Applications,
2012-Nov.
Conference Proceeding
In this paper we successfully demonstrate the reach improvement of spectrum-sliced dense wavelength-division-multiplexed passive optical network (SS-DWDM PON) where amplified spontaneous emission ...(ASE) source is used as a seed light. Investigated optical system is built on the ITU-T DWDM frequency grid, defined in recommendation G.694.1 and therefore it is potentially much more compatible with other already existing WDM PON optical systems. In this way it is possible to replace the classic WDM PON system with our proposed extended-reach spectrum-sliced WDM PON system and reduce complexity of network architecture as well as cost per one user. The maximum reach of the spectrum-sliced dense wavelength-division-multiplexed passive optical network (SS-DWDM PON) system with data transmission speed 2.5 Gbit/s can be fairly limited by chromatic dispersion (CD) because of large optical bandwidth per channel compared to the bit rate. And therefore, dispersion degrades the performance of a SS-DWDM PON system more than it is observed in conventional laser-based system. This paper contains the investigation of high speed 8-channel spectrum-sliced DWDM PON system with efficient CD compensation methods like dispersion compensating fiber (DCF) and fiber Bragg grating (FBG). It is shown that CD compensation has an important role for guaranteed downstream optical link performance and maximum transmission line length of high speed SS-DWDM PON system. Results show that FBG used for CD compensation in high speed spectrum-sliced dense WDM PON systems provide better accumulated CD compensation and increase optical link length up to 150% while DCF fiber provides up to 130% reach improvement.
The spectrum sliced dense wavelength division multiplexed passive optical network (SS-DWDM PON) is a cost effective and power efficient solution for passive optical access networks to satisfy the ...growing worldwide demand for transmission capacity. In this paper we successfully demonstrate the investigation of 16 channel high-speed SS-DWDM PON system with data rate 2.5 Gbit/s per channel where broadband ASE source is realized using two EDFA amplifiers in cascade mode. Originally resulting ASE spectrum on the output of EDFA is irregular and manipulation with EDFA parameters must be done to make it more flat. Flat optical spectrum of ASE source is an important premise to achieve minimal output power level fluctuations of obtained channels after spectrum slicing and provide stable data transmission with BER<;1·10 -10 over the specified fiber optical link length. Maximal reach of realized SS-DWDM PON system is evaluated as well as the performance of proposed broadband ASE source.
The spectrum sliced dense wavelength division multiplexed passive optical network (SS-DWDM PON) is a cost effective and power efficient solution for passive optical access networks to satisfy the ...growing worldwide demand for transmission capacity. Originally resulting ASE spectrum on the output of EDFA is irregular and manipulation with EDFA parameters must be done to make it more flat. Flat optical spectrum of ASE source is an important premise to achieve minimal output power level fluctuations of obtained channels after spectrum slicing operation and provide stable data transmission with BER<;10 -10 over the specified fiber optical link length. In this paper we successfully demonstrate the reach improvement by implementation of chromatic dispersion compensation for cost effective spectrum-sliced 16-channel DWDM PON system with data rate 2.5 Gbit/s per channel as well as realization of broadband ASE light source with output power +23 dBm, channel power variation 0.42 dBm and flat spectrum in wavelength range from 1545.32 nm to 1558.98 nm.
This paper revealed the maximum transmission distance for wavelength division multiplexed (WDM) fiber optic transmission system (FOTS) over which the optical signals can be transmitted and then ...successfully detected on the other fiber end with appropriate error probability below the maximum permissible threshold. The studied mixed WDM system complies to the following configuration scheme: {1 st (f c =193.0250 THz), 4 th (f c =192.8250 THz) and 7 th (f c =193.2375 THz) channels: NRZ-OOK, R=10 Gbit/s - 2 nd (f c =193.1000 THz), 5 th (f c =192.8875 THz) and 8 th (f c =193.3000 THz) channels: 2-POLSK, R=40 Gbit/s - 3 rd (f c =193.1750 THz), 6 th (f c =192.9625 THz) and 9 th (f c =193.3750 THz) channels: NRZ - DPSK, R=40 Gbit/s}. As it can be seen optical signals are transmitted with two different per channel bitrates - 10 and 40 Gbit/s and non-return to zero encoded on-off keying (NRZ-OOK) modulation format is used for the manipulation with optical signal's amplitude. Whereas NRZ encoded differential phase shift keying (NRZ-DPSK) is used for the manipulating with signal's phase and, finally, orthogonal binary polarization shift keying (2-POLSK) is used for the manipulation with signal's state of polarization. The maximum transmission distance was detected using the number of iteration loops which simulate the sector of FOTS line.
Increasing data rates in the fiber optics transmission systems leads to more new limiting factors which complicates the signal transmission. One of such factors is the optical fiber birefringence ...induced polarization mode dispersion (PMD). Although PMD value in typical standard single mode fiber is quite low (less than 0.2 ps/âkm for ITU-T G.652D standard fiber) higher data rates sets higher requirements for signal quality. In this research comparison between three different modulation formats (traditional on-off keying, differential phase shift keying (DPSK) and polarization shift keying (PolSK)) is given at different optical fiber PMD levels and data transmission rates. It is found that most significant impact of PMD is to traditional on-off keying modulation format, but the best performance showed DPSK modulated signals.
The authors have investigated the most efficient realization of mixed chromatic dispersion (CD) compensation schemes for high speed combined high density wavelength division multiplexing (HDWDM) ...systems. This research is performed with OptSim 5.1 simulation software. In this research it is shown that chromatic dispersion compensation scheme has a crucial role for guaranteed performance in combined HDWM transmission channels. Dispersion management strategy is needed when increasing the bit rate per channel by a factor of four. Therefore, the most efficient CD compensation scheme must be found for realized combined fiber optical transmission system. Authors have revealed that implementation of asymmetrical CD compensation schemes in pre-compensation and post-compensation modules are the most efficient and that it enables the best possible channel's bit error ratio (BER) values.
Authors have measured differential group delay of fiber Bragg grating band-pass filter with 50 GHz full width half maximum bandwidth with method based on Jones Matrix Eigen-analysis and have ...evaluated efficient bandwidth employing 2.5 Gbit/s and 10.3125 Gbit/s optical signals to draw out limitations for realization of dense wavelength division multiplexing-direct broadband access system.
