Richard S. Vodhanel

10-Gb/s transmission of 1.55-μm directly modulated signal over 100 km of negative dispersion fiber

In this letter, the largest transmission distance (100 km) ever reported for a commercially available 10-Gb/s 1.55-/spl mu/m directly modulated signal over a single fiber link without using any dispersion compensation is demonstrated. The achieved dispersion-length product for a Q-factor greater than 9.4 dB (bit-error rate less than 10/sup -15/) was about 750 ps/nm. The fiber that enabled such long transmission distance with high dispersion tolerance is a nonzero dispersion-shifted fiber that has negative dispersion in the entire usable bandwidth (1280-1620 nm) and is optimized for operation with directly modulated lasers. The excellent single-channel transmission performance that we achieved can be expected also from wavelength-division-multiplexed systems with channels across the erbium-doped fiber amplifier bands.

Demonstration of negative dispersion fibers for DWDM metropolitan area networks

We present a detailed experimental and theoretical study, showing that a novel nonzero dispersion-shifted fiber with negative dispersion enhances the capabilities of metropolitan area optical systems, while at the same time, reducing the system cost by eliminating the need of dispersion compensation. The performance of this dispersion-optimized fiber was studied using different types of optical transmitters for both 1310- and 1550-nm wavelength windows and for both 2.5-and 10-Gb/s bit rates. It is shown that this new fiber extends the nonregenerated distance up to 300 km when directly modulated distributed feedback (DFB) laser transmitters at 2.5 Gb/s are used. The negative dispersion characteristics of the fiber also enhance the transmission performance in metropolitan area networks with transmitters that use electroabsorption (EA) modulator integrated distributed feedback (DFB) lasers, which are biased for positive chirp. In the case of 10 Gb/s, externally modulated signals (using either EA-DFBs or external modulated lasers using Mach-Zehnder modulators), we predict that the maximum reach that can be accomplished without dispersion compensation is more than 200 km for both 100- and 200-GHz channel spacing. To our knowledge, this is the first demonstration of the capabilities of a nonzero dispersion-shifted fiber with negative dispersion for metropolitan applications.

Extraction of laser rate equations parameters for representative simulations of metropolitan-area transmission systems and networks

Abstract In this paper we present procedures for the extraction of laser rate equation parameters. The parameters are extracted using fitting of static and dynamic measurements with simple theoretical expressions. In particular, chirp related parameters are extracted directly through measured chirp and power waveforms. The extracted parameters are used in a large-signal rate equation laser model to calculate the power and chirp waveforms. The simulations are compared with experiments and the agreement is excellent. The procedures have been applied to directly modulated lasers having different chirp characteristics and designed for either 2.5 or 10 Gb/s operation. Using the rate equation laser model with the extracted parameters, we performed a simulation study to identify the value of employing a negative dispersion fiber in metro-area networks. It is shown that dispersion shifted fibers with negative dispersion across the entire usable fiber bandwidth (1280–1620 nm) advances the performance of directly modulated lasers used in wavelength division multiplexed metropolitan-area transmission systems and networks. At 2.5 Gb/s transmission over 300 km of negative dispersion fibers is possible for directly modulated lasers across the erbium doped fiber amplifier bandwidth, while at 10 Gb/s an impressive distance of 100 km can be achieved.

Bipolar optical FSK transmission experiments at 150 Mbit/s and 1 Gbit/s

Bipolar direct modulation has been used to overcome the nonuniform low-frequency modulation response of distributed-feedback laser transmitter in optical FSK transmission experiments at 150 Mb/s and 1 Gb/s. The heterodyne receiver sensitivity was -48 dBm for 150 Mb/s and -39 dBm for Gb/s, independently of the pseudorandom pattern length. There was no degradation in receiver sensitivity with transmission through more than 100 km of fiber. >

Transmission performance of a 1.5-μm 2.5-Gb/s directly modulated tunable VCSEL

We present experimental and theoretical transmission performance results for a novel 1.5-/spl mu/m 2.5-Gb/s directly modulated wavelength tunable vertical-cavity surface-emitting laser over different fiber types. Uncompensated reach of 100-800 km is demonstrated depending on the fiber choice.

Transport performance of an 80-Gb/s WDM regional area transparent ring network utilizing directly modulated lasers

The transport performance of a regional area wavelength division multiplexing (WDM) transparent optical network is studied. We present excellent performance results (Q factors for all received signals greater than 10 with small power penalties) for a ring network based on application-optimized cost-effective optical layer components and fiber. The network consists of six network nodes, interconnected with 86.5-km spans of uncompensated negative dispersion fiber, resulting in a maximum transmission distance around the ring of 519 km, and it supports 32 directly modulated channels operating at 2.5 Gb/s (80-Gb/s network capacity). The novel design of the network nodes ensures great flexibility in terms of scalability and transparency, as well as great performance. To our knowledge, the capacity-length product of this transparent network, using cost-effective directly modulated lasers (DMLs) and no dispersion compensation, is the highest ever reported.

Measurements of laser rate equation parameters for simulating the performance of directly modulated 2.5 Gb/s Metro area transmission systems and networks

In this work, we present a detailed study on the extraction procedures for rate equation parameters. Parameters related to the chirp characteristics are extracted directly from chirp measurements. Moreover, the procedures have been applied for the characterization of directly modulated lasers (DMLs) with different characteristics. The laser dynamics were accurately simulated as shown by comparing the measured and simulated results for both chirp and power waveforms. The extracted parameters were then used in transmission simulation to identify the best fiber choice for metropolitan area networks utilizing DMLs. This work can be a useful tool whenever the influence of DML characteristics on the overall performance of a system must be accurately evaluated.

Effects of multi-path interference (MPI) on the performance of transmission systems using Fabry-Perot lasers and short bend insensitive jumper fibers

We measured the effects of MPI for systems that include Fabry-Perot lasers and short bend insensitive fibers and analyzed contributions from different factors including both laser and fiber characteristics.

Chromatic dispersion compensated 25Gb/s multimode VCSEL transmission around 850nm with a MMF jumper

A special multimode fiber jumper was designed to provide desired DMD characteristics for a multimode fiber link for chromatic dispersion compensation. 25 Gb/s VCSEL transmission experiment was conducted. Performance benefit of CD compensation was observed.

16 channel, 10 Gb/s DWDM transmission of directly modulated lasers with 100 GHz channel spacing over 100 km of negative dispersion fiber

Error free uncompensated DWDM transmission over 100 km of MetroCor fiber was demonstrated with a 16 channel DML system with 100 GHz channel spacing in the C-band. The nearly tenfold increase in the uncompensated transmission distance facilitated by the use of MetroCor fiber compared to standard single-mode fibers, using low cost 10 Gb/s directly modulated lasers, is an attractive solution for the development of cost effective metropolitan area networks. In this experiment, a total capacity of 160 Gb/s was demonstrated. Since the C and L bands can accommodate 80 channels with a 100 GHz spacing, these results indicate that a total capacity of 800 Gb/s can be achieved with 10 Gb/s DMLs in metro DWDM networks.