The behavior of the differential group delay (DGD) root-mean-square (rms) value is investigated for a buried G.652 fiber line in a metropolitan fiber plant outside Stockholm, Sweden. This study presents measurement results from two different measurement periods where the same fiber and the same measurement equipment was used. In total, ~ 2800 hours of measurements were performed. As expected, the recorded DGD rms-value varied with time. The measured standard deviation for the statistics of the DGD rms-value fits reasonably well with values presented in literature. The fiber line, which showed a DGD rms-value of 0.45 ps in average, had an extremely long time constant. Even after ~ 2800 hours of measurements we have not closed in on the expected asymptotic distribution of the measured DGD rms-value.

Transmission of 16 nonreturn-to-zero on-off keying channels at 40 Gb/s with 100-GHz spacing is demonstrated over 2800 km. This record transmission distance was made possible by the 2-dB increase in power tolerance obtained when employing the cost-effective asynchronous phase modulation technique.

A Method to Calculate PMD-Induced Eye-Opening Penalty Signal Outage for RZ-Modulated Signal Formats

A model of a long optical communication line consisting of alternating segments with anomalous and normal dispersion, whose lengths are picked up randomly from a certain interval, is considered. As the first stage of the analysis, we calculate small changes of parameters of a quasi-Gaussian pulse passing a double-segment cell by means of the variational approximation (VA) and approximate the evolution of the pulse passing many cells by smoothed ODEs with random coefficients, which are solved numerically. Next, we perform systematic direct simulations of the model. Results are presented as dependences of the pulse’s mean width, and standard deviation of the width from its mean value, on

Presented is the first experimental study of 67%-duty-cycle alternate-phase return-to-zero (APRZ) generated by a single-Mach-Zehnder (MZM) transmitter, in terms of nonlinear tolerance, comparing it with 33% RZ, 33% APRZ, and standard 67% CSRZ over a 465 km link at 40 Gbit/s.

0.6 ps long-term stable, high extinction-ratio optical pulse generation at 40 GHz has been demonstrated based on simultaneous two-arm modulation of a LN Mach-Zehnder modulator.

We use the cost-effective APM technique to increase the non-linear tolerance of NRZ-OOK, and we demonstrate, in a recirculating loop experiment, the transmission over 2800 km SSMF of 16 NRZ-OOK 40 Gb/s channels with 100 GHz spacing.

In this paper, we present a fast and computational low-intense method to calculate signal outage due to polarization mode dispersion (PMD) for RZ-based modulation formats. The presented tool serves mainly as a fast algorithm to calculate qualitative measures of signal outage for these modulation formats.

Polarization-independent all-optical demultiplexing of 160-Gb/s optical time-division-multiplexed data based on cross-phase-modulation-induced wavelength shifting in highly nonlinear fiber (HNLF) has been experimentally demonstrated with a maximum power penalty of 0.8 dB due to signal polarization variations. The method uses a simple and easy-to-implement single-path polarization-diversity scheme by placing a short piece of polarization-maintaining fiber before the HNLF.

Article BER Model for Rx ISI Effects in WDM Systems Accounting for General LPF Impulse Responses and for Correlation of Quadrature and Polarization Noise Contributions was published on March 1, 2007 in the journal Journal of Optical Communications (volume 28, issue 1).

Increasing the channel bit rate is an efficient way to upgrade traffic capacity in installed photonic networks. At bit rates of the order of 40 Gb/s, on-off keying (OOK) transmission becomes severely impaired by non-linear effects – especially Intra-channel Four-Wave Mixing (IFWM) – which limit the power at which the signal can be transmitted, and ultimately the transmission distance. This paper reviews three techniques for the suppression of IFWM. Numerical, and experimental studies are presented, both in the laboratory and in installed transmission systems.

We propose a method that enables accurate ASK system modelling even when the detected optical field obeys non-Gaussian statistics with a substantial amount of nonlinear phase noise accumulated in the fibre due to signal-noise interaction.

The asynchronous phase modulation (APM) scheme is experimentally studied for the first time. APM is shown to increase the power tolerance of NRZ-OOK over a 3x75-km link.

F. Parmigiani, S. Asimakis, N. Sugimoto, F. Koizumi, P. Petropoulos, DJ Richardson, 2R regenerator based on a 2-m-long highly nonlinear bismuth oxide fiber Optics Express 2006 Vol. 14 (12) pp. 5038-5044

Intrachannel four-wave mixing (IFWM) represents main source of impairments in fiber transmission at 40 Gb/s. A number of phase modulation techniques have been proposed to suppress the IFWM. In this paper, we study a cost-effective way of increasing the nonlinear tolerance of a 40-Gb/s wavelength division multiplexing transmission system by asynchronous phase modulation (APM). This can be achieved with one phase modulator placed after the wavelength multiplexer so that cost is shared by all channels. We show, by means of numerical simulations and laboratory experiments, that APM greatly improves the performance of ON-OFF-keying transmission.

We investigate six different methods presented in literature to estimate eye-opening penalty for dispersion-compensating fiber Bragg gratings with aid of the grating's ripple function. The investigation is based on theoretical ripple functions as well on measurement results of three continuously chirped gratings. The gratings in question offer full wavelength coverage between 1530 nm and 1565 nm. We will show that the eye-opening penalty depends on the phase and frequency of the grating's ripple function as well as to pattern length and to pulse form of the signal used. Since the estimation methods do not account for these properties, their accuracy is shown to be limited.

We propose a novel method for effective simulation of optical fiber transmission system performance with nonlinear interaction between the amplified spontaneous emission noise and the modulated optical signal employing on-off keying. The method enables a standard analytical description of the receiver operation even when the detected optical field obeys non-Gaussian statistics with a substantial amount of nonlinear phase noise accumulated along the fiber link due to strong signal-noise interaction.

A 40 Gbit/s transmission experiment on an installed link designed for dense wavelength division multiplexing (DWDM) transmission at 10 Gbit/s, using the alternate-phase return-to-zero (APRZ) modulation format is presented. The experiment confirms the superior nonlinear tolerance of APRZ, even with typical DWDM filtering.