E. Meissner

Dispersion management for the transmission of mixed data rates of 40 Gb/s and 10 Gb/s in the same fiber

For 10 Gb/s and 40 Gb/s NRZ signals the maximum reach of a WDM transmission system depends on the optimization of the inline dispersion scheme, which is different for both data rates for SPM limited transmission systems. Therefore, a mixture of both data rates in the same fiber may cause an impairment of the system performance. This can be reduced introducing additional pre-compensation. The value for the optimum pre-compensation varies with the inline dispersion scheme and the launch power. A design rule to determine the optimum pre-compensation was derived empirically for SSMF and NZDSF. For fixed inline dispersion compensation on SSMF, the maximum reduction of the system reach without pre-compensation is found to be up to 6 dB, compared to optimized inline dispersion compensation schemes. By applying optimal pre-compensation this impairment can be reduced to less than 1 dB. For NZDSF with pre-compensation the system performance can also be improved significantly. Thus WDM systems using different line rates at the individual wavelengths are possible with only a small penalty.

Direct modulation 565 Mb/s DPSK experiment with 62.3 dB loss span and endless polarization control

Optical DPSK at 565 Mb/s is performed by direct modulation of a narrow-linewidth 1.5- mu m SL-QW-DFB (strain layer-quantum well-distributed feedback) transmitter laser. The bipolar RZ drive signal has no DC component which allows penalty-free transmission of 2/sup 23/-1 bit patterns. The heterodyne receiver contains an endless polarization controller with <6.3 or >12 rad/s tracking speed, depending on the tolerable intensity loss. A loss span of 62.3 dB is achieved,without degradation due to stimulated Brillouin scattering.<<ETX>>

Optimizing the wavelength configuration for FWM-based demultiplexing in a SOA

In this paper efficient FWM demultiplexing in a SOA using a well chosen wavelength configuration is presented. A 160-Gbit/s OTDM signal is demultiplexed error-free to a base rate as high as 40 Gbit/s.

High-speed dual p-i-n photodiodes for optical coherent receivers

A monolithically integrated planar dual InGaAs pin photodiode with a 3 dB bandwidth of 18 GHz has been fabricated for balanced optical coherent receiver application. The photodiodes are designed for front and backside butt-jointed fiber coupling. They exhibit a very low dark current of 10 pA at -10V, a capacitance of 85 fF and a responsivity of 1 A/W. After 4500 h operation no chip failure has occurred. High impedance front-end modules have been assembled with a 3 dB bandwidth of 8.9 GHz and a coupling efficiency of more than 90 percent (-0.5 dB).

Ultra-High Receiver Sensitivity For Coherent Transmission Systems At 565/140 Mbit/S Using DPSK/FSK Modulation.

It is widely known that heterodyne detection provides an improved receiver sensitivity and selectivity compared to direct detection. Therefore heterodyne systems are very interesting for both long haul transmission and local networks. For long haul transmission the up to 15 dB improvement in receiver sensitivity at high data rates will be the most important issue. This means that the receiver spacing will increase by about 75 km. The most sensitive PSK and DPSK modulation formats are of interest for this application. In LANs and distribution networks it will be very advantageous to transmit a great number of densely spaced channels over one fiber. In the subscriber premises, a heterodyne receiver selects one of them without any switching element. Since the FSK modulation format is very tolerant to laser linewidth and since low cost is an important issue for broadcast systems, FSK systems at moderate data rates with tunable DFB lasers will be used for this application. We demonstrate two transmission experiments with 565 Mbit/s DPSK and 140 Mbit/s FSK modulation, respectively, using different laser types.