The behavior of the differential group delay (DGD)root-mean-square (rms) value is investigated for a buried G.652fiber line in a metropolitan fiber plant outside Stockholm, Sweden.This study presents measurement results from two different mea-surement periods where the same fiber and the same measurementequipment was used. In total,2800 hours of measurements wereperformed. As expected, the recorded DGD rms-value variedwith time. The measured standard deviation for the statistics ofthe DGD rms-value fits reasonably well with values presentedin literature. The fiber line, which showed a DGD rms-value of0.45 ps in average, had an extremely long time constant. Evenafter2800 hours of measurements we have not closed in on theexpected asymptotic distribution of the measured DGD rms-value

We use the cost-effective APM technique to increase the non-linear tolerance of NRZOOK, 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.

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.

We use the cost-e®ective 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. © 2007 Optical Society of America.

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.

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. 

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.

In [1] a rigorous model for Rx ISI effects caused by optical and electrical filtering in the receiver was presented aiming at 10-40 Gbit/s WDM system design applications. The model is applicable for general types of optical and electrical filtering. The model assumes Gaussian distributed noise contributions in the optical domain for in-phase and quadrature noise components in orthogonal polarization states and that these noise contributions are un-correlated. The optical filter is specified via the correlation function and the electrical filter via the impulse response. A limitation of the model was that only positive impulse responses could be accounted for when the noise properties of the receiver is specified. We present here an extension of the model in [1] to account in rigorous form also for negative impulse responses when determining the noise properties of the receiver. As a major theoretical result the formulation is extended to account for correlation between quadrature noise contributions - as it may e.g. be caused by four wave mixing effects in the transmission fiber - and noise contributions in orthogonal polarizations states - that may be due to saturation effects in cascaded optical amplifiers in the transmission path. The formulation leads to a Hermitian form of the covariance matrix. It is however to be noted that the covariance matrix in the situation with positive impulse response is positive definite (with positive eigenvalues) whereas in the general situation it is not positive definite and may have positive as well as negative eigenvalues. However, the Hermitian form allows in all cases a straightforward analytical formulation of the moment generating function (MGF) which in turn specifies the BER. The model is included in the simulation tool VPI-transmissionMaker™WDM and numerical examples for a 10 Gbit/s pre-amplified Rx shows that the influence of a negative impulse response may be (up to) several orders of magnitude in the BER.