L. Boivin

Investigation and design rules of supercontinuum sources for WDM applications

We investigate supercontinuum generation (SC) in normal dispersion fiber in order to assess the feasibility of WDM transmitters based on SC sources. The interest of this case lies in its relative simplicity, and in the high coherence of the SC spectrum that is obtained through this process. We demonstrate that seed pulse shape influences both SC spectrum flatness and its noise characteristics. Simple design rules for the maximum spectrum magnification and for the corresponding fiber length are proposed. We show numerically and experimentally that a proper design can keep the amplitude noise of the SC spectrum comparable with the amplitude noise of the seed pulse.

A supercontinuum source based on an electroabsorption-modulated laser for long distance DWDM transmission

We describe a 40-channel X 9.953 Gbit/s dense wavelength-division multiplexed (DWDM) transmitter based on spectrum-slicing of supercontinuum light generated from an electroabsorption-modulated laser (EML). Error-free transmission of all channels over 544 km of standard fiber is demonstrated.

400 Gb/s transmission (40 Ch./spl times/10 Gb/s) over 544 km from a spectrum-sliced supercontinuum source

We report the error-free transmission over 544 km of standard fiber of 40 channels at 9.953 Gb/s from a spectrum-sliced supercontinuum source. All but three of the transmitted channels have error floors better than log(BER)=/spl sim/16.

Transmission over 362 km of 110 channels at 2.35 Gb/s from a spectrum-sliced femtosecond laser

We use temporal spectrum-slicing and optical time-division multiplexing to obtain 110 wavelength channels at 2.35 Gb/s from a single femtosecond fiber laser. We show that the output of this transmitter can be propagated over 362 km of standard single mode fiber using periodic amplification and dispersion compensation. Most transmitted channels have Q factors larger than 18.34 dB corresponding to error floors below 10/sup -16/.

Effect of fiber nonlinearity on the propagation of highly chirped pulses in a WDM system

Summary form only given. Fiber nonlinearities generally result in system impairments. Consequently it is necessary to employ countermeasures, such as spans with alternating signs of dispersion, to counteract their detrimental effects. However, we observe for pulses that initially have a large anomalous chirp, fiber nonlinearities can actually have beneficial effects. Namely we observe that these pulses undergo spectral narrowing due to the interaction of self-phase-modulation with their initial chirp.

Testing optical time-division multiplexed transmission systems with interleaved bit sequences

We compare experimentally the performance of a 10 Gb/s channel encoded with a pseudo-random bit sequence and with interleaved bit sequences typical of OTDM experiments. For linear transmission conditions IBS patterns are found to yield slightly worse performances.

Supercontinuum source based on an electroabsorption modulated laser for long distance DWDM transmission

Summary form only given. Dense wavelength-division multiplexed (DWDM) transmitters based on spectrum-slicing of supercontinuum (SC) light have attracted renewed interest recently. So far, all transmission experiments with SC-DWDM sources have used actively mode-locked lasers to seed the supercontinuum, raising concerns about the stability and the practicality of these systems. Picosecond seed pulses can however also be obtained from a DFB laser using a variety of techniques. In this paper, we describe for an example a 40-channel 400 Gbit/s SC-DWDM transmitter where seed pulses are obtained from an electroabsorption-modulated DFB laser (EML). We demonstrate the error-free transmission of all channels over 7 spans (544 km) of standard single-mode fiber. To our knowledge, this is the first system experiment using a mode-locked-laser-free SC-DWDM transmitter.

103-channel chirped-pulse WDM transmitter

Chirped-pulse wavelength-division multiplexing (CPWDM) was recently proposed as a new technique for generating a comb of WDM channels. A key feature of this approach is the possibility to generate and encode data on a very large number of channels using a single short-pulse laser and a single time-division multiplexing modulator. This characteristic makes CPWDM attractive for applications where many channels with moderate bit rates per channels (10-622 Mbit/s) are required. In this paper, we report the generation of 103 independent WDM channels at a bit rate of 37 Mbit/s each from a single CPWDM transmitter. This represents more than a three-fold increase in the number of channels previously reported for this type of source and is, to our knowledge, the largest number of channels reported to date for any WDM transmitter.

Chirped-pulse wavelength-division multiplexing at 155 Mbit/s with active feed-forward channel equalization

The broad bandwidth of femtosecond lasers make them potential sources for wavelength-division multiplexing (WDM) systems. The difficulty is in spectrally slicing out the channels and modulating them. A technique for doing both simultaneously was recently demonstrated. In this technique, known as chirped-pulse WDM (CPWDM), a femtosecond pulse is linearly chirped by passage through a dispersive delay line such as a single-mode fiber. Here we demonstrate the scaling of this concept to 155-MHz repetition rate and the use of a feed-forward technique to actively equalize the channels, increasing the number of channels by approximately 50%.

Suppression of coherent Rayleigh noise in a bi-directional fiber transmission link using a modelocked laser transmitter

In this paper, we demonstrate a complete suppression of coherent Rayleigh noise in a bi-directional fiber link using a modelocked laser transmitter. The noise suppression arises because optical beat interference at the receiver occurs mostly at frequencies beyond the receiver bandwidth, and cannot contribute to RF noise. Our results suggest that noise from multi-path interference in general can be reduced dramatically by use of spectrally-sliced transmitters.