Ramon Gutierrez-Castrejon

Uni-directional time-domain bulk SOA Simulator considering carrier depletion by amplified spontaneous emission

A novel and comprehensive model for semiconductor optical amplifiers (SOAs) to be used in high bit rate (10-160 Gb/s) optical communication systems is presented. Its uni-directional and time-domain character makes it very appropriate to be efficiently integrated in a high-level systems simulator, as is explained through a comprehensive comparison and classification of prominent SOA models/simulators. Despite its fast execution time, the corresponding SOA simulator accurately considers a manifold of ultra-fast nonlinear effects and dynamics and, for the first time within a uni-directional simulator, the impact of amplified spontaneous emission (ASE) on the carrier dynamics. According to the numerical results here presented, the latter effect is fundamental in the simulation of SOAs longer than 0.5 mm.

Design and Technical Feasibility of Next 400 GbE 40-km PMD Based on 16

The technical feasibility of a straightforward and cost-effective extension of the current 100 Gb/s Ethernet 40-km physical medium dependent (PMD) architecture for single-mode fiber to a higher speed of 400 Gb/s is demonstrated by means of simulations. A 16-wavelength configuration, each running at 25 Gb/s in non-return-to-zero modulation format and using plain direct detection is numerically analyzed and optimized. It is shown that error-free performance is achievable when a channel plan slightly shifted from the zero-dispersion wavelength of the transmission fiber and having a channel spacing of 400 GHz is utilized. However, to meet the power budget requirement in a fiber having an attenuation coefficient of 0.50 dB/km, a semiconductor optical pre-amplifier with a small-signal gain of 23 dB and transmitters having a minimum average output power of +2.9 dBm and an extinction ratio of 8 dB have to be employed. Based on the calculated design margins, the use of flexible active devices is suggested for span lengths shorter than 40 km.

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We present an advanced and comprehensive semiconductor optical amplifier model to analyze the propagation and amplification of 10 to, in principle, 1280 Gb/s ultra-short optical pulse sequences. Through appropriate transformation, the partial differential propagation-rate equation problem is numerically solved in a two-dimensional grid of fine resolution. The corresponding simulator, entirely programmed in the graphical language LabVIEW, is compared to an identical simulator implemented in the popular high-level text-based language Matlab. Special care has been taken to implement the same set of algorithms using equivalent codes for each language, such that a fair and objective one-to-one comparison can be carried out. In terms of computational time the LabVIEW simulator shows a tenfold outperformance, compared to its text-based identical counterpart implemented in Matlab, when typical bit sequences at 40 Gb/s with a length of 8 to 1024 bits are tested. The performance results presented here apply to a broader set of device modeling scenarios.

25 Gbps Architecture

The proposal and technical feasibility of a wavelength-division multiplexed system consisting of eight optical channels, each transporting data at 50Gb/s in NRZ modulation format, are presented. It is numerically demonstrated that, aided by a semiconductor optical pre-amplifier with 23dB of gain and setting the laser output power of an electro-absorption-based transmitter to +7.9dBm, a propagation distance of 40km over conventional single-mode optical fiber can be achieved with a BER < 1×10-13. Despite its high sensitivity, dispersion power penalty is minimized by setting a 400GHz channel plan in O-band whose center is slightly red-shifted from the zero-dispersion wavelength of the fiber. Moreover, non-zero dispersion is found to be useful in reducing the deleterious amplifier nonlinear gain modulation at mid-range distances, whereas four-wave mixing is found to play a practically inconsequential role. In agreement with previous results derived for 25Gb/s multi-channel links, optical signal-to-noise ratio degradation becomes the prominent corrupting factor at long fiber span lengths. The proposed architecture thus represents an alternative for the implementation of the physical layer of next-generation Ethernet or similar metropolitan data networks.

Using LabVIEW™ for advanced nonlinear optoelectronic device simulations in high-speed optical communications

The proposal, analysis and technical feasibility of a 4 × 100 Gb/s 40-km coherent optical system over single-mode fiber for next generation Ethernet data transmission are presented. The link is based on a 100 GHz-spaced channel plan on C-band that employs DP-QPSK as advanced modulation format. Typical coherent transmitters and receivers with state-of-the-art digital signal processing functionalities are considered, avoiding the use of any type of optical amplification or forward error correction. According to the analysis, an optical transmitter power per channel between -5.6 dBm and -1.0 dBm guarantees the error-free operation (BER > 1×10-13) of the 40-km transmission link. Further system details are also presented. This simulation work leverages the use of coherent technology at metro network level.

An alternative for the implementation of 40-km reach Ethernet at 400Gb/s using an 8Ö50Gb/s PHY at 1310nm with SOA pre-amplification

This chapter presents an overview of the most recent modeling and simulation techniques for the analysis and engineering of all the major devices and network elements that comprise a state-of-the-art optical communications system and network. The subject is presented by creating different abstraction levels in device modeling and building on the simulation fundamentals through computer modeling paradigms.

Technical feasibility of a 400 Gb/s unamplified WDM coherent transmission system for ethernet over 40 km of single-mode fiber

A novel simulator useful to design and analyze the functionality of advanced integrated optical chips is presented and demonstrated through an example of a wavelength converter operating at 40 Gb/s. Written in a modular graphical programming language, the simulator is intuitive, fast, flexible and powerful. It represents an attractive alternative to more traditional approaches

State-of-the-Art in Device and Network Element Level Modeling

A numerical investigation of the performance of an automatic gain-controlled semiconductor optical preamplified receiver for a 4 x 25 Gbits/s wavelength division multiplexing transmission system with a 0-40 km reach is presented. We show that the control scheme acting on the semiconductor optical amplifier (SOA) gain increases the input power dynamic range of the optical receiver, thus allowing the transmission system to operate error free regardless of fiber length. In contrast, a fixed-gain optical receiver shows poor performance that is due to SOA nonlinearity and photodiode overload, which are well captured by the corresponding simulation models. The device represents a practical alternative to the next-generation high-speed Ethernet technology.

A Simulator for Integrated Optoelectronic Devices

The technical feasibility of an unamplified 4 × 100 Gb/s wavelength division multiplexed direct-detection optical OFDM system that uses electro-absorption modulators (EAM) as transmitters is numerically demonstrated for up to 10-km reach of single-mode fiber (SMF) in O-band and 800 GHz-channel spacing. Based on the use of currently available optical components, most of which were developed for the current long-reach Ethernet standard, operating around 1300 nm, error-free operation (pre-FEC BER <; 3.8E-5) is achieved. The architecture here put forward represents a backward compatibility alternative that can be used to define next-generation 2- and 10-km 400 Gb/s Ethernet standard.

Gain-controlled semiconductor optical preamplifier for the 100 Gbit/s 40 km Ethernet receiver

The nonlinear response of a bulk semiconductor optical pre-amplifier in a 16 × 25 Gb/s WDM implementation for the next 40-km Ethernet link, operating at 400 Gbps is numerically analysed. It is found that the effect of carrier-heating-induced four-wave mixing for channel spacing values between 200 and 800 GHz is rather modest despite the large number of optical channels. In contrast, cross-gain modulation is uncovered as the main impairment, and its dependence on the system channel-spacing value is quantified and explained in terms of the interplay between amplifier saturation and fibre dispersion. Useful design parameters for the optoelectronic transceivers, operating at 25.781 Gb/s in traditional on-off keying scheme, are put forward.