Chromatic Dispersion Limitations Research Articles

400GBASE-LR4 and 400GBASE-LR8 Transmission Reach Maximization Using Bismuth-Doped Fiber Amplifiers

We extend the transmission distance of 400GBASE-LR4 and 400GBASE-LR8 systems by introducing simple and ultrawideband single-stage bismuth-doped fiber amplifiers (BDFAs). The transmission reach of emerging 400GBASE-LR4 and 400GBASE-LR8 transceivers was successfully extended from 10 km to 20 and 90 km, respectively. The transmission links were stable over seven days for both systems. Furthermore, we demonstrate that the transmission reach was maximized up to the chromatic dispersion limit and show the applicability of BDFAs for upgrading the transmission reach of cost-effective transceivers to meet the requirements of 400ZR applications. This offers a reasonable solution for improving the power budget and extending the reach of existing data center interconnections with 400GBASE-LR4/LR8 transceivers.

PAM-N—Fundamental Limits in Chromatic Dispersive-Uncompensated Channels

The fundamental chromatic dispersion limit for an optical communication N-level pulse amplitude modulation (PAM-N) format without any dispersion compensating module is calculated. The main result of this analysis shows that in a non-dispersion-compensated channel, the product β2B2L (where β2, L, and B are the dispersion coefficient, fiber length, and the Baud rate, respectively) is bounded by a number, which depends only on the number of levels N. In particular, β2B2L < 0.318, β2B2L < 0.212, and β2B2L < 0.14 for N values of 2, 4, and 8, respectively. Moreover, an analytical expression for a noisy channel’s power penalty was formulated. This analytic expression shows high agreement with numerical simulations. To the best of our knowledge, this is the first time that such a fundamental limit has been formulated for PAM-N systems.

100 Gbps/λ PON downstream O- and C-band alternatives using direct-detection and linear-impairment equalization [Invited

The future-generation passive optical network (PON) physical layer, targeting 100 Gbps/wavelength, will have to deal with severe optoelectronics bandwidth and chromatic dispersion limitations. In this paper, largely extending our Optical Fiber Communication Conference (OFC) 2020 invited paper, we review 100 Gbps/wavelength PON downstream alternatives over standard single-mode fiber in the O- and C-bands, analyzing three modulation formats (PAM-4, partial-response PAM-4, and PAM-8), two types of direct-detection receivers (APD- and SOA + PIN-based), and three digital reception strategies (unequalized, feed-forward equalized, and decision-feedback equalized). We evaluate by means of simulations the performance of these alternatives under different optoelectronics bandwidth and dispersion scenarios, identifying O-band feasible solutions able to reach 20 km of fiber and an optical path loss of at least 29 dB over a wide wavelength range of operation. Finally, we compare two digitally precompensated modulation schemes that are highly tolerant of chromatic dispersion, showing a possible extension to C-band operation, preserving direct-detection and linear-impairment equalization at the optical network unit side.

Method to improve the performance of the optical modulation format identification system based on asynchronous amplitude histogram

Abstract A method to improve the performance of the asynchronous amplitude histogram (AAH) based optical modulation format identification system is proposed. It is demonstrated that with additional static dispersion compensation modules (SDCMs), polarization and non-polarization multiplexed (PM/NPM) signals can be distinguished simply from the AAH peak position difference, while the stringent chromatic dispersion limit imposed on the MFI method can be expanded up to desired values by selectively enabling the SDCMs to minimize the width to area ratio (WAR) of the AAH. Numerical simulations and experiments are carried out to demonstrate the effectiveness of this method.

Simulation of SSB-LC With D-EML for Extended PON Beyond the Chromatic Dispersion Limit

The dual electro-absorption modulated laser (D-EML) is a transmitter technology based on distributed feedback laser and electro-absorption modulator integrated on the same chip with dual independent-access modulation. The D-EML allows the adjustment of its optical signal spectral content by controlling independently the laser and modulator amplitude modulations in order to enhance the transmission distance beyond usual chromatic dispersion limit without increasing consumption, cost, and complexity. We develop a D-EML model based on experimental characterization in order to demonstrate by simulation the interest of dual-modulation format for optical systems at 10, 25, and 40 Gb/s.

Impact of chromatic dispersion on DPSK and DQPSK direct-detection optical systems

Chromatic dispersion (CD) limitations for binary and quaternary phase-modulated systems using direct detection receivers are analyzed by numerical simulation, comparing the results with intensity-modulated systems, considering both IMDD (Intensity-Modulation Direct-Detection) and Duobinary formats. Three different receiver structures are assumed and many transmitter and receiver filter bandwidths are spanned, to find out how much CD penalty varies depending on such alternative solutions. Penalty was assessed by means of a very accurate performance estimation semi-analytical technique based on Karhunen-Loeve series, which theoretically converges to the exact bit-error rate for direct detection optical systems in the presence of both ase noise and inter-symbol interference. The results show that DQPSK is the most resilient format to CD, as expected, but it is also the less sensitive format to filter bandwidth variations.

Frequency Downconverting Fiber Grating-Based Beamformers for High-Capacity Phased Arrays

A technique is presented to remove the beat noise limitation in multibeam beam formers using a simple all-optical microwave frequency downconversion technique prior to performing the true-time delay equalization in the optical domain. The frequency conversion concept enables a significant increase in beam-number capac ity to be achieved due to the elimination of beat noise limits, and also effectively removes the power penalty due to chromatic dispersion limitations of the chirped grating units in the beamformer. The Bragg grating requirements for the frequency converting beamforming network are analyzed and show that tanh-profile apodized gratings can meet the isolation, reflectivity, and narrow bandwidth requirements. For an X-band phased array, more than a twofold increase in beam capacity is shown through the use of the frequency conversion technique with the grating-based beamformer, and the resulting beamformer has the minimum number of optical interconnects with true-time delay operation.

The phase-shaped binary transmission (PSBT): a new technique to transmit far beyond the chromatic dispersion limit

This letter presents the phase-shaped binary transmissions (PSBT), which allow to bridge more than 200 km in the linear regime over standard dispersive fibers. These transmissions are based on /spl pi/ phase shifts occurring in the middle of some "0" hits inside a binary sequence. An analytical explanation is given. This letter also explains why 2-intensity level duobinary transmissions, which are a particular case of PSBT, were able to bridge experimentally up to 243 km.

Monolithic integration of multiple-quantum-well lasers and modulators for high-speed transmission

Monolithically integrated single frequency lasers and electroabsorption modulators are attracting considerable interest as optical sources for long-haul and high-bit-rate fiber-optic links. Their frequency chirpless nature has indeed allowed nonreturn-to-zero (NRZ) transmission beyond the chromatic dispersion limit. They also offer a great potential as soliton pulse generators. This paper discusses the many integration schemes devised for their realization with particular emphasis on the identical active layer (IAL) approach. Recent progress in their high-speed applications is reported.

Chromatic and Polarization Dispersion Limitations in Coherent Optical BPSK and QPSK Systems

Chromatic and Polarization Dispersion Limitations in Coherent Optical BPSK and QPSK Systems

Chromatic dispersion limitations for FSK and DPSK systems with direct detection receivers

Chromatic dispersion limitations for frequency-shift keying (FSK) and differential phase-shift keying (DPSK) systems using narrow-linewidth lasers and direct-detection receivers are discussed. The limitations are found to depend strongly on the receiver configuration. The receiver must include an optical frequency discriminator, such as a Mach-Zehnder interferometer, and either a balanced photodetector pair or a single photodetector at the interferometer output. For transmission at 1550 nm over 1310-nm optimized single-mode fiber, the distance for 1-dB eye closure penalty at 10 Gb/s ranges from 20 to 70 km, depending on the modulation format and the receiver configuration. >

Chromatic dispersion limitations due to semiconductor laser chirping in conventional and dispersion-shifted single-mode fiber systems

The effect of dynamic linewidth broadening due to frequency chirping in directly modulated single-mode lasers, combined with dispersive single-mode fibers, has been investigated using computer simulation. It has been found that dispersion-shifted fibers have a potential advantage over conventional single-mode fibers for dual-window multigigabit-per-second bidirectional and wavelength-division-multiplexed transmission systems.

Chromatic dispersion limitations in coherent lightwave transmission systems

Computer simulation is used to evaluate the chromatic dispersion limitations for both various coherent lightwave transmission systems and direct-detection on-off keying (OOK) systems. The results show that for a 2-dB dispersion penalty the maximum modulation rate ranges from 5 to 9 Gb/s for systems operating at 1.55 mu m with 15 ps/km-nm of chromatic dispersion and 100 km of fiber. The effect is less severe for OOK systems and most severe in coherent detection systems. Simulation results are in agreement with a available experimental data. >

Chromatic dispersion limitations in coherent optical fibre transmission systems

Computer simulation results indicate that the chromatic dispersion limitation in coherent single-mode-fibre systems is more severe than in direct-detection systems. As an example, for transmission through 100km of fibre at 1550nm, where chromatic dispersion is 15ps/km nm, the modulation rate that produces 2dB dispersion penalty ranges from 5 to lOGbit/s, depending on the modulation format.