A comparison between different PMD compensation techniques

We quantify the benefits of using different techniques for compensation of polarization mode dispersion (PMD) in fiber-optic communication systems by means of numerical simulations. This is done both with respect to PMD-induced pulse broadening and in terms of system outage probability for different data formats [nonreturn-to-zero (NRZ) and return-to-zero (RZ)]. Attention is focused on simple and relevant single- and double-stage post-transmission compensators with a few degrees of freedom (DOF). It is generally believed that a PMD compensator with a polarization controller and a variable delay line can only compensate the PMD to the first order. We show, from analytical results, the counterintuitive fact that this scheme can also partially compensate for higher order PMD. We also investigate the benefit of using a polarizer as compensation element where the optical average power can be used as a feedback signal     

Signal generation and transmission at 40, 80, and 160 Gb/s using a fiber-optical parametric pulse source

Short return-to-zero pulses (/spl sim/2 ps) are generated at bit rates of 40, 80, and 160 Gb/s using a fiber-optical parametric amplifier. The performance of the parametric pulse source is evaluated both back-to-back and in a 110-km transmission link. A receiver sensitivity of -33 dBm back-to-back was achieved after demultiplexing from 160 to 10 Gb/s. The power penalty at 160 Gb/s due to 110-km transmission was less than 2 dB. Very short pulses (0.5 ps) were also achieved when using the parametric amplifier as a compressor.     

Experimental quantification of soliton robustness topolarization-mode dispersion in dispersion-managed systems

We have, for the first time, observed and experimentally quantified the soliton robustness to polarization-mode dispersion (PMD) in a dispersion-managed (DM) fiber link. Long-term measurements were performed in a system where the PMD-characteristics were varying randomly over time. The results show that DM solitons are very robust, at least for low map strengths (0相似文献   

A comparison between NRZ and RZ data formats with respect toPMD-induced system degradation

We quantify the polarization-mode dispersion (PMD)-induced system outage probability by means of numerical simulations for nonreturn-to-zero (NRZ) and return-to-zero (RZ) data formats with proper comparative conditions and find that RZ performs better than NRZ. We also study the impact of the RZ duty-factor and the tradeoff between power margin and acceptable PMD     

Robustness of dispersion-managed solitons to the polarization-modedispersion in optical fibers

The robustness of dispersion-managed (DM) solitons to polarization-mode dispersion (PMD) is studied by numerical simulations. It is shown clearly that DM solitons are robust to PMD, and generally, DM solitons are more robust to PMD than conventional solitons. The robustness of DM solitons depends on both map strength and average group velocity dispersion (GVD). We show that the larger the map strength and average GVD, the more robust are the DM solitons to PMD, which is due to the increased power of DM solitons with the large map strength and average GVD     

High-performance optical-fiber-nonlinearity-based optical waveform monitoring

An all-optical waveform sampling system with simultaneous submilliwatt optical signal sensitivity (20-dB signal-to-noise ratio) and subpicosecond temporal resolution over more than 60-nm optical bandwidth is demonstrated in this paper. The optical sampling was implemented by four-wave mixing in a 10-m highly nonlinear fiber using a sampling pulse source with a sampling pulse peak power of only 16 W. The sampling performance was evaluated in terms of sensitivity, temporal resolution, and optical bandwidth with respect to fiber length, sampling pulse source wavelength offset from the zero-dispersion wavelength of the highly nonlinear fiber, sampling pulse peak power, and walk-off due to chromatic dispersion. This paper also presents a summary of the available methods to achieve polarization-independent optical sampling as well as a brief summary of the available sampling pulse sources viable for optical sampling.     

Fiber-optic parametric amplifier in a loop mirror configuration

A configuration of the fiber-optic parametric amplifier (FOPA) using an optical loop mirror is presented and evaluated. Previously presented setups usually suffer a 10-dB loss on the input for the signal wavelength. The setup presented in this letter allows, in principle, virtually lossless combination and separation of pump and signal. In addition, over 30-dB suppression of the pump was achieved in this configuration. Bit-error-rate measurements using the FOPA as preamplifier were compared to a thermal limited receiver. The receiver sensitivity for the FOPA was -30 dBm, which was 10 dB better than the thermally limited receiver.     

DM solitons in long-haul DWDM systems at 40 Gb/s with nonlinear interactions and PMD

The authors investigate for the first time how polarization mode dispersion and nonlinear interactions affect dense wavelength division multiplexing dispersion management-soliton long-haul transmission using Monte Carlo simulations. They also discuss how the system is affected by an increasing number of wavelength channels.     

Noise characteristics of fiber optical parametric amplifiers

We derive an analytical theory for the noise figure of an undepleted and lossless fiber optical parametric amplifier (FOPA). Both the signal and the wavelength converted idler are investigated. Our theory is applicable for both an ideal pump power source, as well as a noisy one. We find that a noisy pump source can severely degrade the performance at high gain due to the stochastic gain-variations the signal and idler will experience. The theory is compared with Monte Carlo simulations of the FOPA and an excellent agreement is obtained. Simulations in the gain-depleted region show the possibility to reach below quantum-limited, phase-insensitive amplification for single channel transmission.     

Statistics of PMD in recirculating loops

The statistical distribution of polarization-mode dispersion in a recirculating loop is investigated. Numerical simulations are performed in both Jones and Stokes space and are verified by experiments. The probability distribution of the differential group delay (DGD) is obtained numerically, theoretically, and experimentally. As the number of circulations increase, the probability density function of the DGD approaches a uniform distribution.